cost cm1101 workshop

27th ECIS Conference 1 - 6 September 2013, Sofia, Bulgaria

Smart Coatings Based on pH-Responsive Micelles

Inna Dewald1*, Munish Chanana1, Julia Gensel1, Johann Erath1, Eva Betthausen2, Axel H.E. Müller2,3, Andreas Fery1

1 University of Bayreuth, Physical Chemistry II, D-95440 Bayreuth 2 University of Bayreuth, Macromolecular Chemistry II, D-95440 Bayreuth

3 Johannes Gutenberg University Mainz, Institute of Organic Chemistry, D-55128 Mainz * - [email protected]

In recent years, formation of a multitude of smart coatings using macromolecular building blocks has been demonstrated. Typical examples are brush type architectures or films formed by layer-by-layer self assembly. In this work, we investigate the potential of responsive polymeric particles in size ranges from sub-microns to few micrometers for this purpose. The use of colloidal particles has several advantages from a material-science perspective, e.g. the colloidal building blocks can be stimulus-responsive and multi-functional on the single particle level, while coatings can be formed by simple physisorption onto solid substrates. Using the layer-by-layer approach for pH-responsive block-copolymer micelles, a facile and elegant preparation method for responsive thin films, leads to coatings with novel properties, internal hierarchy and collective stimulus response, which stems from the integrated nanostructures as building blocks.[1]

We investigate the effects of pH and salt-concentration-changes, on surface properties of these coatings, such as charge density, swelling state and composition, and explore their potential for applications such as cell repellent surfaces [2] and anti-fouling coatings which change their surface characteristics in response to cellular metabolism.[3]

Literature:

1. Gensel J.1, Dewald I.1, Erath J.1, Betthausen E.2, Müller A. H. E.2, Fery A.1, Reversible swelling transitions in stimuli-responsive layer-by-layer films containing block copolymer micelles, Chem. Sci., 2013, 4, 325-334.

2. Gensel J.1, Betthausen E.2, Hasenöhrl C.1, Trenkenschuh K.1, Hund M.1, Boulmedais F.1, Schaaf P., Müller A. H. E.2 and Fery A.1, Surface immobilized block copolymer micelles with switchable accessibility of hydrophobic pockets, Soft Matter, 2011, 7, 11144-11153.

3. Gensel J.1, T. Borke, Pazos Pérez N.1, Fery A.1, Andreeva D. V.1, Betthausen E.2, Müller A. H. E.2, Möhwald H. and Skorb E. V., Cavitation Engineered 3D Networks and Their Application in Active Surface Construction, Adv. Mater., 2012, 24, 985-989.


Application of Humidity-Scanning QCM-D Method for Surfactant Phase Studies

Gesche Graf 1, Vitaly Kocherbitov*1

1 – Malmö University, Sweden * - [email protected]

Accurate phase studies of surfactants are time and sample consuming. Since large amounts of samples are required, long time is needed to achieve equilibrium distribution of water between liquid crystalline phases. An alternative approach would be in using small amounts of samples, which would strongly decrease the time needed for obtaining equilibrium distribution of water. Working with small amounts, on the other hand, involves another complication: transfer of samples into a cell where the actual measurement is performed inevitably changes the water content of the sample. A solution to this problem can be in preparing the required concentrations in situ in the equipment that performs the measurements of physical properties. For binary surfactant-water phase diagram the best way to do it is to scan water content from a dry surfactant to a wet system and to measure changes occurring during this process.

We recently tested a newly developed humidity scanning QCM-D method to investigate the hydration properties and the phase behaviour of Dimethyldodecylamine-N-Oxide (DDAO). In this method the humidity is set up by LiCl salt solution with continuously changing concentration separated from the sample by a membrane penetrable for water vapour. Only few tens of micrograms of surfactant are needed for a full continuous scan in the range of 11-97% relative humidity at 25 oC. The absorbed amount of water is calculated from the changes of frequencies and dissipations during water sorption. The results showed formation of a crystal hydrate, lamellar, bicontinuous cubic and hexagonal phases during the humidity scanning. The water activities of the phase transitions were in good agreement with results obtained by water sorption calorimetry1. The overtone behaviour of frequencies and dissipations correlated with rheological properties of the solid and liquid crystalline phases. The results show that humidity scanning QCM-D method can be used for surfactants phase studies. However, the method needs further improvement to increase the accuracy of the liquid crystalline phases masses measurements.

Literature:

1. Kocherbitov V, Söderman O. 2006. Hydration of Dimethyldodecylamine-N-Oxide: Enthalpy and Entropy Driven Processes. J. Phys. Chem. B 110: 13649-13655.

Acknowledgements:

The Biofilms Research Center for Biointerfaces is acknowledged for financial support.


Green Route for Template Removal from Mesostructured Titania

J.L. Blin1, K. Assaker1, B. Lebeau2, C. Marichal2, C. Carteret3, L. Vidal2, M.J. Stébé1

1 – Equipe Nano, UMR SRSMC N° 7565 Université de Lorraine, Faculté des Sciences, BP 70239, F-54506 Vandoeuvre-les-Nancy cedex, France

2 – Université de Haute Alsace (UHA), CNRS, Equipe Matériaux à Porosité Contrôlée (MPC), IS2M, UMR 7361, ENSCMu, 3bis rue Alfred Werner, F-68093 Mulhouse cedex, France

3 – LCPME UMR 7564, Université de Lorraine, CNRS, 405, rue de Vandoeuvre, F-54600 Villers-lès-Nancy, France

* - [email protected]

We report the first example of P123 surfactant removal from mesostructured titania by water extraction. Mesostructured titania were synthesized by surfactant templating process that combined liquid crystal templating pathway, evaporation induced self-assembly method and basic atmosphere treatment.1,2 Compare with other template extraction processes, our method is low energy consumer, environmentally friendly and it requires no specific devices or instrumentation. The surfactant can be recovered for example by cryodesiccation for reuse. It should be noted that the extraction of P123 by water (about 90%) is more efficient than extraction by ethanol (about 60%), which is an unexpected behavior as regards to the preparation of mesoporous silica material. In that latter case only 25 wt.% of P123 can be removed by water against 75 wt% by ethanol.3

Another advantage of the procedure reported here concerns the formation of anatase nanocrystallites during the extraction of the surfactant molecules by water at room temperature (Fig. 1). Among the common crystalline forms of titania, anatase is generally recognized to be the most active phase. Therefore, the procedure reported here open new potential for industrial development of the TiO2-based photocatalysts.

Fig. 1 : TEM image of water-extracted mesoporous TiO2 at RT 1. K. Zimny, J. Ghambaja, C. Carteret, M.-J. Stébé and J.-L. Blin, New J. Chem., 2010, 34, 2113-2117. 2. K. Zimny, T. Roques-Carmes, C. Carteret, M.J. Stébé, J.L. Blin, J. Phys. Chem. C, 2012, 116, 6585-6594. 3. O. H. Han and Y.K. Bae, Bull. Korean Chem. Soc., 2008, 29, 911-912.


Targeted Drug Delivery Dystems Based on Polyelectrolyte Nanocapsules

Krzysztof Szczepanowicz1*, Marek Piotrowski1, Tomasz Kruk1, Karolina Podgórna1, Piotr Warszyński1

1 – Jerzy Haber Institute of Catalysis and Surface Chemistry Polish academy of Sciences, niezapominajek 8, 30-239 Krakow, Poland


One of the first concept of drug targeting was suggested by Paul Erlich almost a century ago. The hypothetical ‘magic bullet’ consisting of two principal components was proposed. The first component should recognize the target and bind to it, the second should perform therapeutic action. After four decades of research, there have not yet been produced an effective, generally applicable, site-specific drug-delivery system. Nanoencapsulation has high application potential in medicine since it can be used to improve the compatibility of lyophillic, poorly water-soluble or even water-insoluble active compounds with physiological fluids. Additionally, it can protect therapeutic molecules from the destructive influence of an external environment. The modifications of capsules surface (e.g. by pegylation and/or by immobilization of antibodies) allow enhancing the stability and half-life of drug carriers, increase their biodistribution, allow targeting into the required pathological area and responsiveness to local physiological stimuli. Therefore, the present study describes the development of the method of preparation of loaded nanosize capsules and their surface modification for passive and active targeting. Nanocapsules containing model drugs (e.g. anticancer Taxol) were prepared using the method proposed by Szczepanowicz et al. [1]. The oil (chloroform) cores stabilized by AOT/PLL (Poly L-Lyzyne) surface complexes were encapsulated with shells formed by layer-by-layer adsorption of polyelectrolytes using PLL as the polycation and PGA Poly(glutamic acid) as the polyanion. The average size of the obtained capsules was 80 nm. Surface of obtained capsules were modified by pegylation in order to eliminate opsonization and fast clearens from the body, to prolong stay in the blood for extended time in order to increase accumulation in pathological sites with affected and leaky vasculature (tumors) via the enhanced permeability and retention (EPR) effect. The copolymers with PEG chains grafted to a polyelectrolyte backbone were used to immobilize PEG on polyelectrolyte capsules. In order to verify the cytotoxic effect of empty nanocapsules and ones containing drug on selected cells lines the MTT assay was performed. Additionally, leakage of the lactate dehydrogenase protein (LDH) from the cells was measured as an indicator of the loss of membrane integrity after exposure to nanocapsules. Results demonstrate that such nano-scale drug carriers might serve as a novel, promising therapeutic agent for the targeted therapy.

[1] Szczepanowicz Krzysztof et. al, 2010, Formation of Biocompatible Nanocapsules with Emulsion Core and Pegylated Shell by Polyelectrolyte Multilayer Adsorption, Langmuir 26: 12592-12597.

Acknowledgements:

The work was financed by NCN project DEC-2011/03/D/ST5/05635 and the Marian Smoluchowski Krakow Research Consortium - a Leading National Research Centre KNOW supported by the Ministry of Science and Higher Education and the COST Action CM1101.


Development and Structural Characterization of Microemulsions for the Encapsulation of Natural Pyrethrins

A. Kalaitzaki 1,2, V. Papadimitriou1*, G.T. Sotiroudis1, N. Papanikolaou3, F. Karamaouna3, V. Dourtoglou4, A. Xenakis1,2

1 – Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece.

2 – MTM, Faculty of Science and Engineering, Örebro University, Sweden 3 – Benaki Phytopathological Institute, Kifissia, Greece.

4 – VIORYL S.A, Oinofyta, Greece. * - [email protected]

Recent breakthroughs in the development and characterization of materials at the nanometer scale, exhibiting a wide range of novel physico-chemical properties and offering new technological possibilities, have made nanosized systems highly attractive in the field of basic and applied research. Liquid nanosized systems such as micro- and nanoemulsions could be of great fundamental interest offering new technological applications especially in the field of pharmaceutics, nutrition and agriculture. The main aim of the present study was to formulate stable liquid nanodispersions based exclusively on materials approved for human consumption to be used as carriers of pyrethrum, a naturally occurring insecticide. Pyrethrum is a botanical insecticide derived from the white pyrethrum daisy, Tanacetum cinerariifolium, member of the Asteraceae family. Pyrethrum is lipophilic and exhibits high biodegradability by air and sunlight. In this respect water-in-oil microemulsions based on safe, biocompatible components were preferably selected among other types of liquid nanodispersions to be used as novel media for the formulation of extracted natural pyrehthrins. In this regard, an oil of natural source such as lemon oil terpenes and safe nonionic surfactants such as polysorbates were chosen for the construction of the systems. The aqueous phase was a 2:1 mixture of water and glycerol. The phase behavior of these systems was described by pseudo-ternary phase diagrams, which were determined at 25 oC. Furthermore, from the applied research perspective, structural characterization of the proposed microemulsion systems was of great importance. In this respect various techniques, such as Electron Paramagnetic Resonance (EPR) spectroscopy, Dynamic Light Scattering (DLS), Small-angle X-ray scattering (SAXS) and electrical conductivity were carried out to characterize the microemulsion formulations. Finally, efficacy of the pyrethrum containing microemulsions upon two target-insect pests was evaluated.

Literature:

1. Papadimitriou V., Sotiroudis T.G., Xenakis A., Langmuir 2007, 23, 2071-2077. 2. Papadimitriou, V., Tzika, E.D., Pispas, S., Sotiroudis, T.G., Xenakis, A. Colloids and

Surfaces A, 2011, 382, 232. 3. Fanun, M., Papadimitriou, V., Xenakis, A. J. Colloid Inter. Sci., 2011, 361, 115.


Accounting for Ion Specificity through the Poisson-Helmholtz-Boltzmann model

Klemen Bohinc*,1, Ahis Shrestha2, Milan Brumen3, Sylvio May2

1– Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia, 2– Department of Physics, North Dakota State University, Fargo, Nort Dakota, USA

3–Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia


Solvent molecules form a spatially extended hydration shell around each mobile ion in an electrolyte solution. Inter-penetration of the solvent shells gives rise to additional non-electrostatic interactions between ions. Both the steric size of the mobile ions and the structure of the hydration shell leads to ion specificity. The purpose of this work is to incorporate non-electrostatic interactions into the PB theory through the addition of a repulsive Yukawa pair potential between the mobile ions in solution [1]. The Yukawa potential accounts for the solvent-mediated non-electrostatic ion-ion interactions. We employ a local formulation of the mean-field free energy through the use of two auxiliary potentials, an electrostatic and a non-electrostatic potential. Variational minimization of the mean-field free energy leads to two coupled local differential equations, the Poisson-Boltzmann equation and the Helmholtz- Boltzmann equation. Their boundary conditions account for the sources of both the electrostatic and non-electrostatic interactions on the surface of all macroions that reside in the solution. We show that the concentration profiles and free energy of the electric double layer depends sensitively on the Yukawa interaction strengths between the different ion types and on the non-electrostatic interactions of the mobile ions with the macroion. Associating different non-electrostatic interaction strengths with different ion types enables us to incorporate ion specificity into the Poisson-Boltzmann formalism [2].

Literature:

1. Bohinc, K., Sherstha, A., May, S., 2011. The Poisson-Helmholtz-Boltzmann Model, Eur. Phys. J. E., 34: 108. 2 Bohinc, K., Sherstha, A., Brumen, M., May, S., 2012. Poisson-Helmholtz-Boltzmann model of the electric double layer: Analysis of monovalent ionic mixtures, Phys. Rev. E. 85: 031130.


Microemulsions with Ionic Liquids – Interfacial Tension and Microstructure

Jan Christoph Thater*, Violaine Gérard, Cosima Stubenrauch.

Institut für Physikalische Chemie, Universität Stuttgart * - [email protected]

In microemulsions ionic liquids (ILs) may be used as a substitute for either water or oil. Replacing water by a hydrophilic IL leads to microemulsions which are interesting for high temperature applications.1 Hydrophilic ILs that have been used for the formulation of such microemulsions are mainly ethylammonium nitrate (EAN) and imidazolium salts with short alkyl chains. The use of EAN in microemulsions stabilized by alkyl polyethyleneoxide (CiEj) surfactants was reported by Atkin and Warr.2 For a microemulsion consisting of ethylammonium nitrate, an alkane and CiEj they observed a characteristic structure peak in the SAXS spectrum. Kunz and co-workers presented evidence for nanostructured domains swollen with both EAN and [bmim][BF4] as ILs in a microemulsion stabilized by an ionic liquid surfactant.3 On the other hand, hydrophobic ILs may be used in microemulsions as a substitute for traditional oils, which often are hazardous and volatile. For example, microemulsions were formulated with the imidazolium based IL [bmim][PF6], water, and the technical surfactant TX-100.4 In a next step the hexafluorophosphate anion (PF6

-), which is unstable towards hydrolysis, was exchanged by the stable bis-triflimide (NTf2

-) and the phase behaviour of such systems was studied.5 The mentioned studies are promising approaches towards microemulsions with either hydrophilic or hydrophobic ILs. However, a systematic investigation of the microstructure is yet to be done for all systems published so far. Thus we chose to study the system EAN – dodecane – C12E3 (hydrophilic IL) and a microemulsion with [Ali336][NTf2] (hydrophobic IL) and TX-100. We started to work on this topic by firstly measuring the domain sizes of an IL-containing microemulsion with small angle X-ray scattering (SAXS). Secondly, pulse gradient NMR spectroscopy is used to determine whether continuous or discrete structures are present. Since the interfacial tension between the water-rich and the oil-rich phase in traditional microemulsions (containing water and oil) relates to the microstructure, spinning drop tensiometry was used to measure the interfacial tension σab. These results are compared to the well known water – alkane – CiEj microemulsions.

1. O. Zech, S. Thomaier, A. Kolodziejski, D. Touraud, I. Grillo, W. Kunz. 2010. Ionic Liquids in Microemulsions – A Concept To Extend the Conventional Thermal Stability Range of Microemulsions. Chem. Eur. J. 16: 783-786.

2. R. Atkin, G. G. Warr. 2007. Phase Behavior and Microstructure of Microemulsions with a Room-Temperature Ionic Liquid as the Polar Phase. J. Phys. Chem. B 111: 9309-9316.

3. O. Zech, S. Thomaier, P. Bauduin, T. Rück, D. Tourraud, W. Kunz. 2009. J. Phys. Chem 113: 456-473.

4. N. Anjum, M. Guedeau-Boudeville, C. Stubenrauch, A. Mourchid. 2009. Phase Behavior and Microstructure of Microemulsions Containing the Hydrophobic Ionic Liquid 1-Butyl-3-methylimidazolium Hexafluorophosphate. J. Phy. Chem. B 113: 239-244.

5. J. H. Porada, M. Mansueto, S. Laschat, C. Stubenrauch. 2011. Microemulsions with novel hydrophobic ionic liquids. Soft Matter 7: 6805-6810.

Acknowledgements

This work was funded by the German Research Foundation (DFG).


Hydophobicity of Counterion in Micellization Process: Dodecyltrimethylammonium Chloride and

Alkyl-4-Hydroxybenzoates

Ana Kroflič, Bojan Šarac, Janez Cerkovnik, Marija Bešter-Rogač*

Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia


Recently, it has been shown that small changes, such as the position of the substituent on an aromatic ring in the structure of counterions, considerably influence the micellization processes [1, 2]. This effect has been investigated on the aggregation process of dodecyltrimethyl-ammonium chloride (DTAC) in the aqueous solutions of sodium salts of o-, m- and p-hydroxybenzoates (o-HB m-HB and p-HB). Distinctive difference between influence of isomers on the micellization process and structure of aggregates has been observed. In this contribution, our attention will be focused on the influence of the hydrophobicity of counterions on the micellization process of DTAC. The derivates of p-HB, alkyl esters of 4-hydroxybenzoic acid (called also parabens), turned out as a suitable system, because their hydrophobicity can be altered by the length of alkyl chain on the ester group.

The aggregation of DTAC in methyl- and ethyl-paraben sodium salt aqueous solutions has been investigated at several temperatures in the range from 278.15 to 328.15 K by isothermal titration calorimetry, viscosity and electrical conductivity measurements, and 1H NMR spectroscopy.

From obtained data it can be concluded, that hydrophobic electrolyte not only lowers the solubility of the amphiphile in aqueous solution and thus also its critical micelle concentration, but it interacts favourably with the surfactant molecules and enables the formation of higher organized structures. We think that our findings can enlighten the interactions of parabens with cell membrane.

Literature:

1. Šarac Bojan, Cerkovnik Janez, Ancian Bernard, Mériguet Guillaume, Roger Gaëlle M., Durand-Vidal Serge, Bešter-Rogač Marija, 2011. Thermodynamic and NMR Study of Aggregation of Dodecyltrimethylammonium Chloride in Aqueous Sodium Salicylate Solution. Colloid Polym. Sci. 289:1597−1607.

2. Šarac Bojan, Mériguet Guillaume, Ancian Bernard, Bešter-Rogač Marija, 2013. Salicylate Isomers Specific Effect on the Micellization of Dodecyltrimethylammonium Chloride: Large Effects from Small Changes. Langmuir, 29: 4460−4469.


Balance of Enthalpy and Entropy in Depletion Forces

Liel Sapir1, Shahar Sukenik1, Regina Gilman-Politi1, Daniel Harries 1, *

1 – Institute of Chemistry and the Fritz Haber Center, The Hebrew University, Jerusalem, Israel * - [email protected]

Solutes preferentially excluded from macromolecules can drive depletion attractions in important biological and colloidal association processes. The established Asakura-Oosawa model relates depletion forces to the reduction in excluded volume and the ensuing entropy gain upon macromolecular interactions. For example, cosolute-induced protein stabilization or favored protein association are often described in terms of entropically driven “crowding”. In agreement, our recent experiments of peptide folding and supramolecular binding suggest that depletion forces are predominantly entropic for some cosolutes, such as polyethylene glycol polymers. Surprisingly, however, for other solutes such as polyol osmolytes, the main thermodynamic contribution is enthalpic, while the entropic change due to cosolutes can even be unfavorable. To further elucidate the molecular basis of this enthalpic depletion interaction, we used Monte-Carlo simulations of the association of two rod “macromolecules” in binary solutions of simple liquids. By dissecting the free energy change upon approach of the two macromolecules into the respective enthalpic and entropic components, we find that different cosolutes have distinct contributions to their macromolecular stabilization effect, implying different thermodynamic driving mechanisms. Specifically, even for these simple, nonassociative liquids, depletion forces can be completely enthalpic in nature. The underlying interactions responsible for this newly resolved mechanism for depletion forces will be discussed and analyzed.

Literature:

1. Sukenik S, Sapir L, Gilman-Politi R, Harries D. 2013. Diversity in the mechanisms of cosolute action on biomolecular processes. Faraday Disc. 106: 225-237.


Fabrication of SPR nanosensor Using Gold Nanoparticles and Self-Assembled Monolayer Technique for Detection of Cu2+In an

Aqueous Solution

EidAzzam1*, AliAbd El-aal1, OsamaShekhah2, Hassan Arslan2and ChristofWöll2

1. Applied surfactants laboratory, Petrochemicals Department, Egyptian petroleum research institute, 11727 Nasr City, Cairo, Egypt

2. Institut für Funktionelle Grenzflächen (IFG),Karlsruher Institut für Technologie (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany


In this work we investigated the fabrication of surface Plasmon resonance (SPR) nanosensor using gold nanoparticles (AuNPs) chemisorbed onto self assembled monolayer of 10-(3-amino phenoxy) decane-1-thiol on gold substrate. The fabrication process of SPR nanosensor was characterized using different techniques such as infrared reflection-absorption spectra (IRRAS), X-ray photoelectron spectroscopy (XPS) and Atomic force microscope (AFM). The fabricated SPR nanosensor was used for detection of Cu2+ in an aqueous solution using Surface Plasmon Resonance Refractometer.The results confirm the fabrication of new SPR nanosensor. The fabricated SPR nanosensor showed a good activity toward the detection of Cu2+. The detection of Cu2+ in an aqueous solution using the fabricated SPR nansensorwas enhanced in the presence of gold nanoparticles.

Fig.1. Schematic illustrating the fabrication process of the SPR nanosensor.

Step 1: Formation of C10/SAM on gold. Step 2: Chemosorption of AuNPs onto

C10-SAM. Step 3: Immobilization of Cu2+ on C10-SAM and AuNPs.

1.Azzam E.M.S. , Bashir A. , Shekhah O. , Alawady A.R.E. ,Birkner A. , Grunwald Ch. , Wöll Ch., (2009) Fabrication of a surface plasmon resonance biosensor based on gold nanoparticles chemisorbed onto a 1,10-decanedithiol self-assembled monolayer, Thin Solid Films 518, 387-391. 2. YeS.,Shi X., GuW., Zhang Y., Xian Y., A (2012)colorimetric sensor based on catechol-terminated mixed self-assembled monolayers modified gold nanoparticles for ultrasensitive detections of copper ions, Analyst, 137, 3365-3371.


Asymmetric Functionalization of Shape-anisotropic Polymer Nanoparticles

Florian Guignard 1, Marco Lattuada 2*

1 Adolphe Merkle Institute University of Fribourg, Route de l'ancienne Papeterie CP 209 CH-1723 Marly 1, Switzerland


In the research in the field of nanoparticle in the last years, much attention has been devoted to the synthesis of anisotropic nanoparticles, also called Janus Nanoparticles. Anisotropicity may be provided in different ways, usually either in terms of non-homogeneous surface functionalization, or as compartmentalized internal structure. These special features render the nanoparticles much more interesting than their isotropic counterparts, especially regarding their self-assembling properties.

In this work, a two-step emulsion based polymerization has been applied to synthesize shape-anisotropic dumbbell nanoparticles, which size and morphology can be tuned by changing the process parameters. Narrowly distributed surfactant-free polystyrene nanoparticles are used as seeds. They are coated with a random copolymer of styrene and 3-trimethyloxyxilyl propyl acrylate (MPS), bringing silane groups on the surface of the seeds. The particles are then swollen with a monomer solution before a second polymerization. Due to the hydrophilic shell on the surface of the nanoparticles, the newly formed polymer is bulging out of the seeds, giving birth to dumbbell-like nanoparticles. The resulting nanoparticles are not only anisotropic in shape, but also in term of surface chemistry. The first bulb is bearing silane groups coming from the MPS, while the second is only made of polystyrene. This specific feature can be used for further asymmetric functionalize the dumbbells. Silane chemistry can be applied, which will result in the functionalization of the first hemisphere only. Superparamagnetic iron oxide nanoparticles (SPIONS) can be coated by surfactant having silane group, offering the possibility to attach SPIONS only to one bulge. The same approach has been used for platinum nanocrystals, leading to particles that can be used as Janus nanomotors in H2O2 solution.

Fig. 1 TEM picture of monodisperse dumbbell particles


Electrodeposition of Porous Copper Using Colloidal Crystal Templating

Madoka Hasegawa1*, Jiajie Chen1, Jeffrey M. Wheeler1, Rejin Koodakal1, Laetitia Philippe1, and Johann Michler1

1 – Empa - Swiss Federal Laboratories for Materials Science and Technology * - [email protected]

Colloidal crystal templating offers numerous exciting possibilities to synthesize three-dimensionally ordered micro/nano-porous materials of both scientific and technological interests, such as photonic crystals, catalyst, and sensors[1]. Porous materials also show unique mechanical properties. Especially, nano-porous materials are of great interest because such materials will exhibit enhanced mechanical strength despite being low density[2]. In this paper, we present the studies on electrodeposition of micro/nano-porous copper using polystyrene (PS) colloidal crystal templating aming at achieving the high strength and low density material.

A multilayer PS colloidal crystal was used as a template for porous Cu formation. Colloidal crystals of different PS sizes ranging from submicrometer to some micrometer of diameters were employed to synthesize porous Cu films with different pore sizes. Electrodeposition to completely fill interstitial space between PS particles was firstly investigated. Proper wetting of a template seems to be important in order to avoid insufficient infiltration of electrolyte into the narrow channels of template. By dissolsolving PS particles in toluene after electrodeposition, ordered porous structure with a controlled pore size was obtained.

Further strengthening of porous Cu can be acheived by electrodepositin of nanocrystalline Cu[3] and nanotwin Cu[4] whcih exhibit improved mechanical strength. By adjusting plating parameters as well as the bath composition, we obtained Cu deposits with different grain sizes from several tens nm to a few micrometer on an unpatterned substrate. The application of such electrodeposition technique to a PS colloidal crystal template will be shown in this presentation. Furthermore, mechanical properties of porous Cu electrodeposits with different pore sizes and crystal structure will be discussed.

Literature: 1. Stein, A. and Schroden, R.C., Colloidal crystal templating of three-dimensionally ordered

macroporous solids: materials for photonics and beyond. Current Opinion in Solid State and Materials Science, 2001. 5(6): p. 553-564.

2. Biener, J., et al., Size effects on the mechanical behavior of nanoporous Au. Nano Letters, 2006. 6(10): p. 2379-2382.

3. Lu, L., M.L. Sui, and Lu, K., Superplastic extensibility of nanocrystalline copper at room temperature. Science, 2000. 287(5457): p. 1463-1466.

4. Hsiao, H.Y., et al., Unidirectional Growth of Microbumps on (111)-Oriented and Nanotwinned Copper. Science, 2012. 336(6084): p. 1007-1010.


Immobilization of Enzymes onto Silica Particles with Magnetic Core with the Aim to Prepare Recoverable Biosensors

A. M. Vaz, D. Serrano-Ruiz, M. Laurenti, P. Alonso-Cristobal, J. Rubio-Retama, E. Lopez-Cabarcos*

Department of Physical-Chemistry II, Faculty of Pharmacy, Complutense University of Madrid, 28040 Madrid, Spain


We present a methodology to produce recoverable biosensors based on magnetic silica particles covalently attached with enzymes. In order to produce this system, iron oxide clusters with a mean diameter of 68 nm were covered with silica using the Stöber method [1] that produced silica particles of 200 nm of diameter which have a magnetic cluster as core. Their surface was functionalized [2] and subsequently, the functional groups were activated to couple the redox enzyme glucose oxidase (GOx), giving as result glucose biosensors with magnetic properties. The enzymatic activity was evaluated by using the particles as a part of an amperometric biosensor since the new particles were able to catalyze the oxidation of the glucose. In presence of glucose, GOx produced hydrogen peroxide which is transformed at the electrode into a current density that is proportional to the glucose consumed. This response followed a Michaelis-Menten kinetics with Kapp = 10 mM and imax= 26·10-6 A/cm2 (see Fig.1). This result was compared with the response produced by 1 mg of free GOx placed on the electrode (Fig.1). The result of this experiment showed that free GOx produced a signal sixfold greater than the GOx immobilized on the surface of the particles. Furthermore, this device allowed determining the stability and the amount of the immobilized enzyme. The new material can be employed to recover biocatalyst in chemical processes.

Fig. 1 Current response of free GOx compared with magnetic silica GOx particles placed on the working electrode,

Literature:

1. Stöber W, Fink A, Bohn E. 1968 J. Colloid Interface Sci 26, 62-69 2. Serrano-Ruiz D, Rangou S, Avgeropoulos A, Zafeiropoulos NE, López-Cabarcos E,

Rubio-Retama J. 2010 J. Polym. Sci. P. B: Polym. Phys 48, 1668-1675 Acknowledgements:

The authors acknowledge financial support from the Spanish Science and Innovation Ministry (Grant MAT2010-15349) and from COST Action CM1101.


Lanthanide interaction with lipids: The battle against hydration. A combined LB and ITC study

Epameinondas Leontidis 1*, Charoula Georgiou 1, Thomas Delclos 1, Maria Christoforou 1, Marie-Claire Dul 2, Damien Bourgeois 2, Olivier Diat 2

1 – Department of Chemistry, University of Cyprus, PO Box 20537, 1678 Nicosia, Cyprus 2 – Institut de Chimie séparative de Marcoule (ICSM), Bagnols Sur Ceze, 30207 France


A major challenge faced by the nuclear industry is the recycling of spent fuel. The goal of the 4th generation reactors is to recycle fuel efficiently, leaving behind waste with low toxicity. This is a difficult process, since spent fuel contains useful actinides, but also lanthanides and other metal cations that are very difficult to separate from the fuel. The separation from the solution involves classical liquid-liquid extraction steps; these are empirically designed and use non-specific ligands that bind lanthanide and actinide ions, as well as tetravalent ions, and do not extract mono- and divalent ions. Softer interactions are significant in these processes and are poorly understood: the transfer of ions between the extraction phases are not well represented by molecular equilibria.

It has been shown that lipid monolayers can be used to quantitate the affinity of anions for soft matter interfaces, and to assign an interfacial affinity index for each ion [1]. In this work we try to extend these ideas to trivalent lanthanide cations by measuring π-A isotherms of specific lipids in a Langmuir balance in the presence of various concentrations of lanthanide salts. The lipids used in this study should provide a range of interactions with lanthanides, from strong interactions leading to complexation to weaker forces. In addition, the lipids must have water-soluble short-chain analogues that can be used in Isothermal Titration Calorimetry (ITC) experiments to directly assess lanthanide – lipid headgroup interactions. We have opted to use phospholipids, double-chain malonamides, sulfobetaine derivatives of the gemini type, and ceramides. Because lanthanides are very strongly hydrated, their interactions with lipids become more “visible” when the cations lose some part of their tight hydration sheaths. This is achieved in the presence of high concentrations of lithium salts. When dehydrated, lanthanides become considerably “stickier”, and apparently organize the lipid molecules both in solution (where precipitation of various lipid-ion assemblies is often observed), and in the Langmuir monolayers.

Literature:

1. Leontidis Epameinondas, Aroti Andrea. 2009. DPPC liquid-expanded monolayers as model systems to understand the anionic Hofmeister series.2. Ion partitioning is mostly a matter of size. J. Phys. Chem. B: 113, 1460-1467.

Acknowledgements: This work was performed in the context of project ANAΒΑΘΜΙΣΗ/0609/12, funded by the Research Promotion Foundation of Cyprus, and the Structural Funds of the European Union for Cyprus.


Synthesis, Characterization and Antibacterial Properties of Polyrhodanine/Needle-like TiO2 Core/Shell Hybrid Nanostructure

Seyma Ozkan 1, Ebru Yılmaz 2, Zekiye Suludere 3, H. Ibrahim Unal 1*

1Gazi University, Chemistry Department, Smart Materials Research Lab. Ankara, Turkiye 2Gazi University, School of Health Sciences, Ankara, Turkiye

3Gazi University, Biology Department, Ankara, Turkiye * - [email protected]

Rhodanine-derivatives and polyrhodanine have attracted considerable attention in a wide range of applications owing to their unique biological activities, including anticonvulsant, antibacterial, antidiabetic, antiviral, antimicrobial and antihistaminic [1] properties. As a Lewis base, rhodanine-derivaties hold a great promise for functionalization of a wide range of metal-based nanostructures [2]. Presenting such molecules on high-surface area colloidal nanostructures is expected to enhance the efficiency of these desired properties. The aim of this study was to synthesize polyrhodanine/needle-like TiO2 nano structures by polymerizing rhodanine monomer on TiO2 surface where the Fe3+ ions were hold through ionic interactions and acted as initiators. The structural, morphological and thermal properties of these nanoparticles were characterized using FTIR, XRD, SEM, TEM and TGA analysis. Results confirmed the formation of needle-like polyrhodanine/TiO2 core/shell hybrid nanostructures. Through surface functionalization, the nanoparticles were observed to become more stable, thereby solving the agglomeration problem of the nanoparticles. Alterations on the surface properties were characterized by zeta-potential measurements. Antibacterial properties of polyrhodanine/TiO2 nanoparticles were tested against Esherichia coli and Staphylococcus aureus by agar well diffusion method and they were determined to have antibacterial activity against test microorganisms.

Fig. 1 (a) SEM image of TiO2 and (b) TEM image of Polyrhodanine/TiO2 nanocomposite Literature:

1. G.B. Chandrakant, N.J. Gaikwad 2004 Bioorgan. Med. Chem. 12: 2151 2. N. Pourreza, S. Rastegarzadeh 2001 Anal. Chim. Acta 437: 273 Acknowledgements: We are grateful to the Turkish Scientific and Technological Research Council (111 T 637) and COST Action CM1101 for the support of this study.

(a) (b)


Facile Synthesis of Meso/Macroporous Materials in Highly Concentrated Emulsions with a Cubic

Liquid Crystal

J. Nestor 1*, J.Esquena 1, A. Vílchez1, C. Solans1.

1 - Instituto de Química Avanzada de Cataluña (IQAC), Consejo Superior de Investigaciones Científicas (CSIC), and CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN),

Jordi Girona 18-26, 08034 Barcelona, SPAIN. * - [email protected]

Highly concentrated emulsions are characterized by an internal phase volume fraction larger than 0.74, which is the maximum packing of monodisperse spherical droplets [1,2]. Consequently, these emulsions have a compact foam-like structure, which consist in deformed and/or polydispersed droplets, separated by a thin film of continuous phase [1,2]. In our previous studies, silica porous materials were obtained by hydrolysing tetraethyl orthosilicate (TEOS) in the external phase of O/W highly concentrated emulsions, where this external phase was a liquid crystal [3]. However, ethanol released by TEOS hydrolysis produced emulsion instability and also obstructed the formation of ordered mesopores [4].

Very recently, a new simple one-step method has been developed to obtain SiO2 monolithic materials with a bimodal meso- and macroporous pore-size distribution [5]. Sol-gel reactions were carried out in the continuous phase of highly concentrated emulsions with a cubic liquid crystal in this external phase, using a polyoxyethylene alkyl ether surfactant and containing a novel glycol-modified silane, tetra(2-hydroxyethyl) orthosilicate (abbreviated as THEOS). The hydrolysis and condensation reactions of this precursor have been carried out in basic pH, between pH 8.8 and pH 11.4. Interestingly, the ethylene glycol released during condensation reactions does not affect significantly the phase behaviour, and consequently the cubic liquid crystalline phase was stable during the sol-gel reactions. As a result, the cubic phase based emulsions could template the formation of meso/macroporous dual materials, which possess interconnected polydisperse macropores, between 1 and 5 m, and cubic-ordered mesopores, with a narrow pore size distribution around 4 nm. Monoliths with a specific surface area higher than 550 m2 g-1 and bulk density of 0.16 g cm-3 have been obtained.

Fig. 1 Image at a macroscopic scale (left), mesoscopic and nano scale (centre) and small angle X-ray spectra (right) of a meso/macroporous dual material.

1. K. L. Lissant, 1966, The geometry of high-internal-phase-ratio emulsions, J. Colloid Interface Sci., 22, 462-468. 2. J. Esquena, C. Solans, In: Emulsions and Emulsion Stability; Taylor and Francis, New York, 2006. 3. H. Maekawa, J. Esquena, S. Bishop, C. Solans and B.F. Chmelka, 2003, Meso/macroporous inorganic oxide

monoliths from polymer foams, Adv. Mater., 15, 591. 4. J. Esquena; J. Nestor; A. Vílchez; K. Aramaki; C. Solans, 2012, Preparation of mesoporous/macroporous

materials in highly concentrated emulsions based on cubic phases by a single-step method, Langmuir, 12334. 5. J. Nestor; A. Vílchez; C. Solans; J. Esquena, 2013, Facile synthesis of meso/macroporous dual materials with

ordered mesopores using highly concentrated emulsions based on a cubic liquid crystal, Langmuir, 432.


Effect of Nanoparticles on the Surface Properties of Lipid Monolayers with Potential Implication for Lung Surfactant Functionality

Francesca Ravera*, Eduardo Guzmán, Michele Ferrari, Eva Santini, Libero Liggieri.

CNR - Istituto per l'Energetica e le Interfasi, Genova, Italy * - [email protected]

The potential toxicity and the health hazard associated with the exposition to engineered nanoparticles and to nanoparticulate produced by the anthropic activities is a subject of increasing relevance in many fields such as industrial production of nanomaterials and energy from combustion. Investigating the basic interactions of NPs with lung surfactants (LS) is an important step to develop new screening methods, being lungs probably the most important entry point for NPs dispersed in the environment. An effective approach to obtain new insights into the interaction of nanoparticles (NP) with LS is provided by the investigation of relatively simple model systems, based on monolayers of fatty amphiphiles and proteins spread/adsorbed at a fluid interface (air/water interface). This allows the application of well-established methodologies and surface sensitive techniques to investigate the properties and interactions with NPs under equilibrium and dynamic conditions [1,2].

This work focuses on the interaction of mixed lipid monolayers, containing DPPC as main component, with different types of NPs, mainly silica and carbon particulate, presenting different chemical and structural properties (size, shape, degree of hydrophobicity).

This study has been carried out using different tensiometric and surface diagnostic techniques such as the Langmuir trough, coupled with Brewser Angle Microscopy (BAM), AFM and Drop/Bubble tensiometers. The results evidence important NP effects on the physico-chemical properties of the lipid monolayers. In particular, it has been pointed out that the NP penetration into the layers induces significant excluded area effects together with changes in the layer composition, due to the adsorption of specific components. This alters the self organization and the molecular packing in the layer with consequent effects on its mechanical properties.

Furthermore, dilational rheology measurements performed according to the oscillatory barrier method, in a Langmuir trough, and the oscillating drop method in drop/bubble tensiometer have evidenced the alterations induced by the NPs in the mechanical response of the monolayers under dynamic conditions, with important implications for the real lung surfactant system.

To better understand the potential toxicological effects, simulated respiratory cycles has also been used to quantify the effect on the layer functionality by the help of classical cumulative indexes such as normalized Hysteresis Area (HA) and Stability Index (SI) as well as by newly defined parameters such as Total Harmonic Distorsion (THD).

Literature:

1. E. Guzmán, L. Liggieri, E. Santini, M. Ferrari, F. Ravera, Effect of Hydrophilic and Hydrophobic Nanoparticles on the Surface Pressure Response of DPPC monolayers , J. Phys. Chem. C, 2011, 115, 21715–21722.

2. E. Guzmán, L. Liggieri, E. Santini, M. Ferrari, F. Ravera, Influence of Silica Nanoparticles on Dilational Rheology of DPPC – Palmitic Acid Langmuir Monolayers, Soft Matter, 2012, 8, 3938-3948


How Different Can Two Quillaja Bark Saponins (QBS) Be ?

Kamil Wojciechowski 1*, Aleksandra Kezwon 1, Agnieszka Przastek 1

1 – Faculty of Chemistry, Warsaw University of Technology Noakowskiego 3, 00-664 Warsaw, Poland * - [email protected]

Biosurfactants, especially saponins, have a great potential for replacing synthetic surfactants in many formulations, mostly in pharmaceutical and cosmetic industry, but also in food products. Saponins are found in numerous organisms, e.g. in soapwort plant, whose roots were traditionally used as natural soap. Saponins extracted from Quillaja saponaria Molina are available commercially under the name of Quillaja Bark Saponin (QBS) and are approved as food additives. Besides their surfactant properties, saponins have a potential to reduce the cholesterol content in blood, as well as a number of anticancer and antibacterial properties [1], to name just a few. The commercial products, however, rarely contain a single saponin compound with a well-defined structure (Fig. 1) and their content will vary in the final product depending on the source and employed method of purification [2].

In this contribution we discuss the huge variability of surface properties of two commercially available QBS in terms of their adsorption at different fluid-fluid interfaces and interactions with model proteins. For the purpose of this study, three most popular food proteins: lysozyme, β-lactoglobulin and β-casein were chosen as model proteins to study their interfacial interactions with the saponins. The first two proteins are globular and differ in surface charge sign at pH employed (pH 7). This allowed us to study the effect of electrostatic interactions between the saponins and proteins. The third protein is more disordered with no tertiary structure and S–S bridging, and is negatively charged under the pH employed in the study.

Fig. 1 Schematic structure of saponins present in Quillaja bark saponin (QBS) extracts.

Literature:

1. Osbourn Anne, Goss Rebecca J. M., Field Robert A. 2011. The saponins – polar isoprenoids with important and diverse biological activities. Nat. Prod. Rep., 28, 1261-1268

2. Wojciechowski Kamil.2013. Surface activity of saponin from Quillaja bark at the air/water and oil/water interfaces. Coll. Surf. B, 108, 95-102

Acknowledgements: This work was financially supported by the Polish National Science Centre, grant no. DEC-2011/03/B/ST4/00780 and COST CM1101 Action

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O

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O

R3

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O

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R4

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OR1

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28glucuronic acid

triterpene sapogenin


Studies of Formation and Characterisation of Liposomes Formed by Cationic 1,4-dihydropyridine Amphiphile in Various Medias

Oksana Petricenko1, Karlis Pajuste2, Martins Rucins2, Velta Ose3, Mara Plotniece2, Marina Gosteva2, Brigita Cekavicus2, Klavs Pajuste2, Arkadij Sobolev2, Aiva Plotniece2*

1 – Faculty of Physics and Mathematics, University of Latvia, Zellu str. 8, Riga, LV-1002, Latvia 2 – Latvian Institute of Organic Synthesis, Aizkraukles str. 21, Riga, LV-1006, Latvia

3 – Latvian Biomedical Research and Study Centre, Ratsupites str. 1, Riga, LV-1067, Latvia * - [email protected]

Polyfunctional pyridinium amphiphiles based on the 1,4-dihydropyridine (1,4-DHP) core possess self-assembling properties and they can be used for transport of DNA into cells. According to our previous studies some of synthesized compounds (e.g. compound 1: 1,1'-[(3,5-didodecyloxy-carbonyl-4-phenyl-1,4-dihydropyridine-2,6-diil)-dimethylen]bispyridinium dibromide) are more active than DOTAP and PEI 25, well known liposomal and polymeric gene delivery agents [1,2]. Due to the amphiphilic nature of cationic 1,4-DHP molecules it is predictable that they may assemble spontaneously into liposomes in aqueous environment, however interactions of liposomes with biological systems are very complex and complicated processes.

Fig. 1. General structure of cationic lipids (A) [3]; structure of cationic 1,4-DHP amphiphile 1 (B); AFM images of formed liposomes: DMEM (C), DMEM+FBS (D) and PBS (E).

The aim of this work was to study the formation and characterisation of liposomes comprised by compound 1 in various medias - model biological systems.

Formation of the liposomes in the Dulbecco's Modified Eagle Medium (DMEM) and DMEM + fetal bovine serum (FBS) - medias for tests with cell cultures; phosphate buffer (PBS) and aqueous environment was tested. The preliminary results suggested that in the DMEM media at the presence of FBS 1,4-DHP amphiphile 1 formed complexes. Obtained data would be important for design and development of more potent and efficient gene delivery agents. Studies and characterisation of obtained liposomes were performed by AFM, TEM and DLS methods and obtained results will be presented.

Literature: 1. Hyvönen Z., Plotniece A., etc. 2000. Novel cationic amphiphilic 1,4-dihydropyridine derivatives for

DNA delivery. Biochim. Biophys. Acta, 1509, 451-466. 2. Hyvönen Z., Rönkkö S., etc. 2004. Dioleoyl phosphatidylethanolamine and PEG–lipid conjugates

modify DNA delivery mediated by 1,4-dihydropyridine amphiphiles. J. Contr. Release, 99, 177-190. 3. Byk G., Dubertret C., etc. 1998. Synthesis, activity, and structure-activity relationship studies of

novel cationic lipids for DNA transfer. J. Med. Chem., 41, 224-235.

Acknowledgements: Financial support was provided by EuroNanoMed project ″CheTherDel″. Authors are indebted to Dr. D.Erts (Institute of Chemical Physics, University of Latvia) for the assistance with the AFM equipment; to the Institute of Physics, University of Latvia for the assistance with a DLS equipment.


Local pH Gradients Promote Raft-like Domains Polarization in GM1-containing Giant Vesicles

Miglena I. Angelova1,2,*, Galya Staneva3, Nicolas Puff1,2, Hélène Conjeaud1, Michel Seigneuret1

1 – Matière et Systèmes Complexes, UMR 7057, Université Paris-Diderot & CNRS, Paris,France 2 – UFR 925-Physics Dept., Université Pierre et Marie Curie, Paris, France 3 – Institute of Biophysics and Biomedical Engineering, BAS, Sofia, Bulgaria


The influence of an external local pH gradient on the dynamics and topography of raft-mimicking Lo domains in model membranes was studied. Heterogeneous giant unilamellar vesicles (GUV) made of PC, SM, Chol and the ganglioside GM1 were used. The Lo/Ld phase separation was promoted by photosensitization (fluorescent probe Texas Red PE), and the spatial pH gradient in the vicinity of the vesicles was established by local microinjection of acid solutions as shown in our previous studies. The most salient effect of the pH gradient was to provoke segregation of domains and polarization of the GUV. The direction of segregation depended on the type of domain: (i) Lo domains within an Ld phase diffused away from the proton source (downward the proton gradient) and accumulated to the more basic side of the GUV; (ii) Ld domains within an lo phase diffused towards the proton source (upward the proton gradient) and accumulated to the more acidic side of the GUV. This effect was no more observed in the absence of GM1 or when a GM1 analog devoid of sialic acid was substituted, and is therefore due to the acido-basic character of the GM1 headgroup.

Fig. 1 Local pH induced polarization of Lo and Ld domains in GM1 containing GUVs.

Laurdan fluorescence measurements performed with LUVs at various pH, showed that the presence of GM1 led to an increase in lipid packing below pH 3-4, due to impairment of repulsion between GM1 molecules after protonation. Such increase in packing was much higher for Ld vesicles than for Lo vesicles. The propensity of Ld phase to segregate towards the acidic side of a spatial pH gradient might be thermodynamically accounted for by its increased packing as well as the resulting decrease of bilayer thickness mismatch with the Lo phase (decrease of line tension) induced by low pH, [1]. It is suggested that such effects might play a role in cellular polarization processes which involve lateral pH gradients due to segregation of NHE1 H+ exchanger. Literature: 1. Staneva G, Puff N, Seigneuret M, Conjeaud H, Angelova MI. (2012) Langmuir 28: 16327–

16337.


Smart Biocolloids and Interfaces via Direct Reaction of Catechols

D. Ruiz-Molina,1* J. Saiz-Poseu1, B. García2, J. Sedó1, J. Hernando3, F. Busqué3

1 Centro de Investigación en Nanociencia y Nanotecnología, Campus UAB, 08193, Cerdanyola del Valles,Spain 2Fundación Privada ASCAMM, Unidad de Nanotecnología (NANOMM), ParcTecnològic del Vallès, Av.

UniversitatAutònoma, 23 - 08290 Cerdanyola del Vallès, Spain 3Chemistry Department, Universitat Autònoma de Barcelona, Campus UAB 08193, Cerdanyola del Vallès, Spain

[email protected] Mussel-adhesive proteins have been the subject of intensive scientific research associated to their remarkable ability to strongly adhere to virtually all surfaces. This behavior has been attributed to their varying amounts of the non-essential catecholic aminoacid DOPA.[1] Herein we report a new synthetic approach for the fabrication of such catechol-based materials with adherent properties. The mechanism is based on a simple polymerization process in the presence of ammonia [2], in a way reminiscent of melanization reactions. The initial molecule of choice was a catechol bearing a long alkyl chain. The resulting material after polymerization spontaneously self-assembles in the form of nanoparticles that easily stick to different surfaces and materials. As an application, the NPs have been successfully implemented for water remediation of heavy metal ions and are being explored nowadays for drug delivery. On the other side, when this material is placed in non-polar solvents such as hexane, the NPs are dissolved and the polymer is used to obtain coatings thanks to their adhesive properties. Coatings are effective on a representative variety of substrates, both at the nano-/macroscale, without any pretreatment or interphase modification. Whereas a long alkyl chain affords coatings with a persistent hydrophobic character, this methodology can be extended to several other catechols with different ring pendant groups, providing additional surface functionalities such as oleophobic, anti-fouling or anti-bacterial activities [3].

Fig. 1 Right: (a) Molecular structure of the building block. (b) TEM and (c) SEM images of the polymerization product. (d) Fluorescence emission spectrum of the polymer in aqueous solution (λexc=355 nm, λdet>400 nm) and (inset) fluorescence microscopy image of 2-NPs deposited onto glass (λexc=540-552 nm). Left: (a) Schematic representation of the process carried out for coating the substrates with compound 2. (b) TEM images of MWCNT coated with the polymer after being dispersed in a 0.5% (w/v) n-hexane solution for 30 minutes. The green arrows mark the MWCNT wall; the orange arrows point at the coating thickness. (c) Different behavior of blank and treated MWCNT dispersed in water and ethyl acetate.

Literature:

1. J. Sedó, J. Saiz-Poseu, F. Busqué and D. Ruiz-Molina. Adv. Mater. 2013, 25, 653–701 2. J. Saiz-Poseu, J. Sedó, B. García, C. Benaiges, T.Parella , R. Alibés , J. Hernando , F. Busqué and D. Ruiz-Molina. Adv. Mater. 2013, 25, 2066–2070. 3. M. Guardingo, J. Sedó, J. Faraudo, A. Verdaguer, F. Busqué and D. Ruiz-Molina. Small. (2013) submitted.


Effect of Ionic Strength and Molecular Weight on Electrical Properties and Thickness of Polyelectrolyte Bi-layers

Viktoria Milkova *, Tsetska Radeva

Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria * - [email protected]

Electric light scattering from aqueous suspension of positively charged ferric oxide particles (-FeOOH) is investigated in the presence of poly(sodium styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PDADMAC) of different molecular weights, adsorbed sequentially on the particle surface at different ionic strengths. The adsorption is realized over a wide range of NaCl concentration (10-4 to 10-1 M) at pH 4.5 and the suspensions of coated particles are then rinsed to ionic strength of 10−4 M. Our measurements indicate that the amplitude of the electro-optical effect increases with increasing concentration of NaCl from 10-4 to 10-2 M due to the increased amount of polymers, adsorbing in more coiled conformation and on more highly charged particle surface. However, the electro-optical effect started to decrease at further increase of NaCl concentration, more expressively at higher field intensities and for bi-layers with first layer from polyelectrolyte of lower molecular weight. This is accompanied with a significant increase in the thickness of the deposited bi-layers after their rinsing to low ionic strength. We attribute both effects to partial desorption of polyelectrolyte complexes from the particle surface, which disturb the homogeneity of the bi-layer structure. The latter causes an increase in the amount of mechanically trapped water on the particle surface and the thickness of adsorbed bi-layers increases as well. As a result, an elastohydrodynamic effect, which favors perpendicular orientation with respect to the external electric field, becomes possible.

Literature:

1. Milkova V., Radeva Ts. 2013. Effect of ionic strength and molecular weight on electrical properties and thickness of polyelectrolyte bi-layers. Colloids and Surfaces A: Physicochemical and Engineering Aspects 424: 52-58.


Triggered Release of Cells from Composite Microcapsules

Shwan Hamad1, Simeon Stoyanov2 and Vesselin Paunov1*

1 – Surfactant&Colloid Group, Department of Chemistry, University of Hull, HU67RX, Hull, UK 2 – Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, the

Netherlands; Laboratory of Physical Chemistry and Colloid Science, Wageningen, University, 6703 HB Wageningen, The Netherlands


We report the fabrication of novel shellac-cells composite microcapsules with programmed release of cells upon change of pH in a narrow range.1 The microcapsules were prepared from yeast cells as a model for probiotics combined with aqueous solution of ammonium shellac doped with a pH sensitive polyelectrolyte, like carboxymethyl cellulose or polyacrylic acid. The cells dispersions in aqueous ammonium shellac were spray-dried or spray co-precipitated to yield composite shellac-cell microcapsules in which the cells retained their viability even when treated with aqueous solutions of very low pH and subjected to mechanical stress. We demonstrated two types of triggered release of cells from these microcapsules with pH trigger and cell growth trigger and evaluated the microcapsules disintegration rates. Depending on the type of the polyelectrolyte integrated in the shellac microcapsules they can be programmed to give very versatile responses ranging from slow cell release to instant swelling and disintegration at higher pH or exposure to growth media. We showed that the cells retain their viability following their release from the microcapsules into the aqueous media. We developed a kinetic model of the kinetics of living cell release from the composite shellac microcapsules triggered by: (i) pH change, which dissolves the shell and (ii) the growth of the encapsulated cells, when placed in a culture media. For pH triggered release of cells from the composite microcapsules, the rate constant of cell release depends on the swelling/dissolution rate of the shellac matrix and varies with the pH of the aqueous media.2 The model links the microcapsules disintegration time with the cell release rate constant. For growth triggered release of cells from the composite microcapsules, the rate constant of cell release depends on concentration of nutrients in the culture media and the cells volume fraction in the microcapsules. In a complementary experimental study we compared the release rate constants of cells from shellac-cell microcapsules at different value of the pH in the aqueous media. We also demonstrated both theoretically and experimentally how the growth rate constants of individual cells compares with the release rates of cells released from microcapsules in culture media. Such composite microcapsules could find applications in formulations for protection and delivery of probiotic and other cell cultures with programmed and triggered release of the encapsulated cells in cell implants, including stem cells and live vaccines. Figure 1. SEM, optical and fluorescence images of composite yeast-shellac microcapsules for triggered release of cells. Litarature:1. Hamad, S.A., Stoyanov, S.D., Paunov, V.N., Soft Matter, 8 (2012) 5069-5077. 2. Hamad, S.A., Stoyanov, S.D., Paunov, V.N., Phys. Chem. Chem. Phys., 15 (2012) 2337-2344.


Growth of Giant Disclike Micelles in Ternary Mixed Surfactant Solutions: Theoretical Model vs. Experimental Data

Svetoslav E. Anachkov,1,* Peter A. Kralchevsky,1 Gergana S. Georgieva,1 Krassimir D. Danov,1 and Kavssery P. Ananthapadmanabhan 2

1Department of Chemical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, 1 J. Bourchier Blvd., 1164 Sofia, Bulgaria

2 Unilever Research & Development, 40 Merritt Blvd., Trumbull, Connecticut 06611, USA * - [email protected]

Our experiments indicate the existence of a high and sharp peak in the viscosity of ternary mixed surfactant solutions vs. the concentration of added fatty acid, the effect being much stronger than previously observed [1]. We investigated mixed solutions of zwitterionic and anionic surfactants with added lauric acid. By conducting light scattering experiments we demonstrate that disclike micelles are present in the region of the viscosity maximum. To interpret the experimental observations, a thermodynamic model of the growth of disclike micelles was developed. The driving force for micellar growth is related to the difference between the mean standard chemical potential per surfactant molecule in the discoidal part of a micelle and in a small

spherical micelle, i.e. 0(s)(d) . Additional complication of the model stems from the fact that the standard chemical potential in the toroidal periphery of the disclike micelle varies with micellar size. Our analysis suggests that the growth of disclike micelles is possible provided

(s)(d)(c) , where the superscripts ‘c’, ‘d’ and ‘s’ stand for cylindrical, discoidal and spherical part of a micelle, respectively. The theoretical model predicts the law of growth of disclike micelles with the rise of surfactant concentration, which differs from the respective law for rodlike micelles. The light scattering data comply very well with the theoretical predictions for the micelle number-average and mass-average aggregation numbers, Nn and Mn .

Fig. 1 The derived law of growth of disclike micelles compares very well with scattering data. Literature:

1. Colafemmina G., Recchia R., Ferrante A.S., Amin S., Palazzo G. 2010. Lauric acid-induced formation of a lyotropic nematic phase of disk-shaped micelles, J. Phys. Chem. B 114: 7250–7260.


Adsorption Layer Properties of Aqueous Solutions of Biantennary Oligoglycines

Stefan Stoyanov*, Roumen Todorov, Elena Mileva

Institute of Physical Chemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria * - [email protected]

Antennary oligoglycines (tectomers) are a novel type of self-assembling molecules. The structure of a tectomer represents several oligoglycine units linked to one common center or a hydrocarbon chain. In the process of synthesis bi-, tri, and tetraantennary oligoglycines can be obtained. A representative of the biantennary oligoglycines is C7H12(-CH2-NH-Gly5)2 (T2), in which between the oligoglycines there is a hydrocarbon chain. The molecules of T2 can form supramolecular structures in the bulk or on solid surfaces [1]. The presence of well defined hydrophilic and hydrophobic parts defines the amphiphilic nature of the molecules and the possibility of self-assembly on the air/solution interface. The formation and properties of adsorption layers from T2 are investigated by a Profile Analysis Tensiometer PAT-1 (SINTERFACE, Berlin, Germany) [2] and KSV NIMA Langmuir Trough (Biolin Scientific, Finland). Stability of foam films stabilized with T2 is studied by the microinterferometric method of Scheludko and Exerowa [3].

Literature:

1. Н.В. Бовин, А.Б. Тузиков, А.А. Чинарев Российские нанотехнологий 3 (2008) 48-62. 2. G. Loglio, P. Pandolfini, R. Miller, A. Makievski, F. Ravera, M. Ferrari, L. Liggieri, in:

Novel Methods to Study Interfacial Layers, D. Moebius and R. Miller (Eds.), Elsevier, Amsterdam, 2001, p. 439

3. D. Exerowa, P. M. Kruglyakov, Foam and Foam Films - Theory, Experiment, Application, Vol. 5 of Studies in Interface Science, Elsevier, Amsterdam, 1998.

Acknowledgements:

The authors gratefully acknowledge the financial support of Project BG 051PO001-3.3.06-0038


Synthesis and Characterization of Polypyrrole/Spherical-TiO2

Core/Shell Hybrid Nanocomposite

Seyda Cabuk1*, Zekiye Suludere2 and H. Ibrahim Unal1

1 – Gazi University, Chemistry Department, Smart Materials Research Lab. Ankara, Turkiye 2 –Gazi University, Science Faculty, Biology Department, Ankara, Turkiye


Polypyrrole (PPy), as a typical conducting polymer, has attracted more attention because of its unique electrical, optical, photoelectric and electrorheological properties. On the other hand, TiO2 nanomaterials have unique electrical and optical properties as well as extensive applications in environmental cleaning and protection, photocatalysis, gas sensing, fabrication of solar cells and batteries and electrorheology [1]. To overcome some limitations in applications, the surface treatment of TiO2 is necessary to improve the compatibility and dispersability [2]. In this study, polypyrrole/spherical-TiO2 core/shell nanostructures by chemical oxidation polymerization of pyrrole monomer on TiO2 surface was investigated. Monodispersed TiO2 spheres were successfully synthesized by hydrolysis and condensation of titanium tetraisopropoxide. The preparation was performed using ammonia as a catalyst in methanol/acetonitrile co-solvent system at room temperature. After spherical TiO2 nanoparticles were surface modified by γ-aminopropyltriethoxysilane coupling agent, conductive polypyrrole (PPy) was chemically grafted on the surface of TiO2 spheres. The structural, morphological and thermal properties of nanoparticles were characterized using FTIR, XRD, TEM, SEM and TGA analysis. TEM image of TiO2 and PPy/TiO2 hybrid nanocomposites are shown in Figure 1. Alterations on the surface properties were characterized by zeta-potential measurements.

Fig. 1 TEM image of (a) spherical TiO2 and (b) PPy/TiO2 nanocomposite

Literature:

1. X. Lu, Q. Zhao, X. Liu, D. Wang, W. Zhang, C. Wang, Y. Wei 2006. Macromol. Rapid Commun. 27:430-434.

2. W. Zhou, T. Xu, X. Wang, E. Zhi, J. Liu, W. Zhang, J. Ji 2013. J. Appl. Polym. Sci. 127: 733-739.

Acknowledgements:

We are grateful to the Turkish Scientific and Technological Research Council (111T637) and COST Action CM1101 for the financial support of this study.

(b) (a)


Field-Induced Sublimation in 2D Colloidal Crystallites

Fernando Martínez-Pedrero2, José E.F. Rubio1, J. Benet1, E. Sanz1, Ramón G. Rubio1* and Francisco Ortega1**

1Department of Physical Chemistry, Faculty of Chemistry, Complutense University, 28040-Madrid, Spain 2CEI Campus Moncloa, UCM-UPM, 28040-Madrid, Spain * - [email protected], ** - [email protected]

Particle laden fluid interfaces have become a very attractive research field because they are very effective in stabilizing emulsions and foams.1 The dynamics of sublimation of 2D crystallites at the liquid/air interface has been studied experimentally in real space by video-microscopy, as well as by Brownian simulations. The crystallites were aggregates of superparamagnetic microparticles, and the sublimation was triggered by switching on an external magnetic field. Figure 1 shows a typical example of the sublimation process under different magnetic fields.

Fig. 1 External field induced sublimation process for two values of the magnetic field: a) 0 mT, b) and c) 1.5 mT, and d) 0.5 mT. c) and d) are magnifications of a) and b)

Both experiments and simulation results lead to scaling dynamic laws that suggest a universal mechanism under strong repulsive interactions. Contrary to conventional melting, the process is cooperative, involving all the particles from the very beginning, and the scaling exponents do not depend on the crystal size. We propose a mechanism, in which sublimation it is completely controlled by the field strength, that recalls a classical theory of crystallization under site-saturated conditions.2

Literature:

1. B.P. Binks, T.S. Horozov, Eds., Colloidal Particles at Liquid Interfaces, 2006. Cambridge Univ. Press, Cambridge

2. S.J. Pas, M.S. Dargusch, and D.R. MacFarlane, 2011. Phys. Chem. Chem. Phys. 13:12033

Acknowledgements: This work has been supported by MINECO under grant FIS2012-38231-C02-01, by COST Action CM1101, and by ESA under grants FASES and PASTA.


Delivery of Epirubicin via Poly(butyl cyanoacrylate) Nanoparticles into Cancer Cell by Endocytosis

Ralica Skrobanska 1, Alexander Evangelatov 1, Georgi Yordanov 2

1 Sofia University “St. Kliment Ohridski”, Faculty of Biology, 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria

2 Sofia University “St. Kliment Ohridski”, Faculty of Chemistry and pharmacy, James Bourchier Blvd., 1164 Sofia, Bulgaria


Recent advancements in nanomedicine enabled the development of nanoparticle therapeutic carriers that hold promise for increasing the therapeutic efficacy of cancer chemotherapy. These drug carriers can be passively targeted and efficiently accumulated into solid tumors via the enhanced permeability and retention effect, so they are ideally suited for the selective delivery of chemotherapeutics in cancer treatment. Nanoparticle drug delivery systems such as polymer nanoparticles, offer a great promise to achieve effective elimination of cancer cells. Particulate systems are known to be able to deliver drugs to cancer tissue with higher efficiency with fewer adverse side effects. Some encapsulated formulations may be further engineered to deliver substances such as inhibitors or therapeutic molecules together with cytotoxic drugs to achieve stronger anticancer activity in tumor cells. Poly(butyl cyanoacrylate) (PBCA) nanoparticles have been extensively proposed for drug delivery to solid tumors and have shown great potential for therapeutic applications. PBCA nanoparticles have been shown to be biocompatible, low immunogenic and easily removed from the body after decomposition.

In the present work, we examined the cytotoxicity of epirubicin in its free form and formulated in PBCA nanoparticles on cervical cancer (Hela) cells. Furthermore, we studied the mechanism, by which PBCA nanocarriers enter into the cells. A colorimetric assay for measuring the activity of cellular enzymes that reduce a tetrazolium dye (MTT) was performed to evaluate the cytotoxicity of the various epirubicin formulations. Drug uptake experiments and studies of the intracellular drug distribution revealed that the amount and localization of the drug depended on its association with PBCA nanocarriers. We performed quantitative evaluation of epirubicin accumulation into cervical cancer cells by using various drug formulations. The intracellular drug distribution was examined by fluorescence microscopy to further understand the drug uptake processes. Observations by transmission electron microscopy (TEM) were carried out to determine whether endocytosis was involved in the uptake of PBCA formulations by the cancer cells. The insights gained from these studies may help to optimize the use of nanoparticle systems for improved cancer chemotherapy.

Acknowledgements: This research was supported by the Bulgarian Science Fund, project DMU 03/111. The authors are also thankful to CMST COST Action CM1101.


Surface Properties of Esterquat and Diesterquat Surfactants – Effect of Molecular Structure and Hydrolysis

Grażyna Para 1*, Jacek Łuczyński 2, Jerzy Palus 2, Wojciech Zieliński 2, Ewelina Jarek 1, Kazimiera Anna Wilk 2, Piotr Warszyński 1

1J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków, Poland, [email protected]

2 Faculty of Chemistry, Wrocław University of Technology, ul. Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland * - [email protected]

Strategies for designing new structures of amphiphilic compounds nowadays include manufacture of so-called environmentally friendly products. These include the compounds containing a labile moiety in the molecule such as: amide, ester, acetal, ether and others, which presence allows the decomposition of molecules into fragments, lowering the environmental exposure levels. The molecule degradation takes place by chemical and/or enzymatic way. On the other hand application of such surfactants for the nanocarriers fabrication opens the possibility of designing new controlled delivery systems, which can be activated by internal or external triggering mechanism. Esterquats are surface active quaternary ammonium compounds having long alkyl chains, in which the hydrophobic part of the moieties are linked to the charged head group via ester bonds R-CO-O- or ROC(O)- [1]. As a consequence of that specific structure, esterquats upon hydrolysis decompose into fragments characterized by various surface activity. Therefore, they may be referred to as „cleavable surfactants”, which usually biodegrade more rapidly than the related alkylquats as they are stable in aqueous solutions only in a narrow pH window for a certain period of time. In the present work we consider both experimentally and theoretically the nonequivalent adsorption of cationic surfactants, having one (i.e., esterquats) and two alkyl chains (diesterquats), taking into account the effect of their hydrolysis. The surface tension isotherms of investigated ammonium salts solutions were determined by the pendant drop shape analysis method. The extended “surface quasi two-dimensional electrolyte” (STDE) model of ionic surfactant adsorption, proposed and developed by Warszynski et al. [2] was applied for the description of the isotherms. Our data show that, depending on the surfactant structure, partial hydrolysis of ester bond can leads to increase of the relative surface activity, more pronounced in the basic conditions (pH 10). That can be explained by formation of alkanoate anions, which can form dimmers with unhydrolyzed surfactants. Even in natural pH we also observe gradual increase of surface activity with time, corresponding to the hydrolytic decomposition of the studied ester- and diesterquats.

Literature:

1. D. Lundberg, M. Stjerndahl, K. Holmberg, Adv. Polym Sci 218 (2008) 57–82 2. P. Warszynski, K. Lunkenheimer, G. Czichocki, Langmuir 18 (2002) 2506.

Acknowledgements: This work was partially financed by National Science Center project UMO-2011/03/B/STA/01217, by a statutory activity subsidy from the Ministry of Science and Higher Education (MSHE) for the Faculty of Chemistry of Wrocław University of Technology as well as by the Marian Smoluchowski Krakow Research Consortium - a Leading National Research Centre KNOW supported by the MSHE and the COST Action CM1101.


Preparation and Colloidal Properties of Covalently Bonded Poly(3,4-ethylenedioxythiophene)/Nanorod-TiO2 Nanocomposite of

a Core/Shell Morphology

Ozlem Erol *and H. Ibrahim Unal

Gazi University, Chemistry Department, Smart Materials Research Lab., Ankara, TURKEY * - [email protected]

Design and fabrication of nanostructures based on metal oxides has attracted much attention in the past decade because of their peculiar electronic, optical, rheological and colloidal properties and their potential applications in industry and technology. One-dimensional titania structures especially become interesting by combining high aspect ratio and specific surface area. We have primarily focused on the preparation of core/shell nanorods that consists of a titania core and conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) shell via covalent bonding to make interfacial interactions between the two components more prominent.

In this study, covalently bonded conducting polymer, PEDOT, coated TiO2 nanoparticles having nanorod structure was prepared and characterized by spectroscopic, morphologic, thermal, and electrical techniques. Nanorod-TiO2 was prepared from TiO2 nanoparticles via a simple hydrothermal process at 180ºC using concentrated NaOH solution. PEDOT/nanorod-TiO2 hybrid nanocomposite of a core–shell morphology was prepared via chemical oxidative polymerization of 3,4-ethylenedioxythiophene monomer in the presence of modified core nanorod-TiO2-grafted-thiophene (nanorod-TiO2-Th) particles that acted as nucleation points for the polymerization of the monomer. TEM analysis revealed that PEDOT coated nanorod-TiO2 particles had a uniform and remarkably thin polymer layer on their surfaces (Fig.1). In addition, successful polymerization of PEDOT shell was confirmed by FTIR, XPS and elemental analysis. From the TGA analysis of the nanocomposite, thermally more stable structure was obtained than PEDOT. Furthermore, after modification, changes in surface properties of nanorod-TiO2 were proved by zeta-potential measurements. Colloidal properties of the PEDOT/nanorod-TiO2 were also investigated under various conditions such as pH, surfactants (anionic, cationic, and nonionic) and electrolytes (mono, di, trivalent, anionic, and cationic).

Fig. 1 TEM images of (a) nanorod-TiO2 and (b) PEDOT/nanorod-TiO2 hybrid nanocomposite

Acknowledgements:

The authors are grateful to the Scientific and Technological Research Council of Turkey (Grant No: 111T637) and COST CM1101 Action for the financial support of this work.

(a) (b)


Electro-Microinterferometric Studies of Water-in-Oil Emulsion Films

Nikolay Panchev1,*, Khristo Khristov1, Jan Czarnecki2

1 – Bulgarian Academy of Sciences, Institute of Physical Chemistry 2 – Department of Chemical & Materials Engineering, University of Alberta

* – [email protected]

Upon application of an electric field across a water/oil/water emulsion film, instability patterns were observed as small white dots in the film’s microscopic image. The characteristic lengths-scale of the instabilities agreed well with theoretical predictions of the dominant wavelength. The films were formed in a thin film apparatus (Sheludko-Exerowa cell) modified such that the oil film separated two aqueous phase compartments, each in contact with a platinum electrode. This modification allows measurements of disjoining pressure while applying electric field to the film. The films were formed from a solution of a block co-polymer Tegopren (Degussa, Germany) in decane. Electric polarization in the form of step function at various potentials was applied across the film below the critical rupture potential using a potentiostat. The characteristic lengths-scales of the instabilities were measured by analyzing each image right after application of the electric field. Furthermore, using linear stability analysis the theoretical dominant wavelengths were calculated taking into account contributions of stabilizing disjoining pressure and de-stabilizing electric field. Electric field induced breakdown of thin films have various applications such as electroporation of bilayer lipid membranes and electrostatic emulsion. While pore nucleation is a known mechanism for breakdown of bilayer lipid membranes, rupture mechanism of thicker films with substantial solvent core such as those observed in petroleum industry is not well understood yet. Various mechanisms such as pore nucleation, dielectric breakdown, and electrohydrodynamic instabilities are proposed as the primary mechanism of breakdown for these films. However, experimental proofs of such mechanisms are limited.


One –Pot Synthesis of Colloidal AgInS2 Nanoparticles

Nadica D. Abazović, Miodrag Mitrić, Milica Beloš, Mirjana I. Čomor*

Laboratory for Radiation Chemistry and Physics, Vinča Institute of Nuclear Sciences

P.O. Box 522, 11001 Belgrade, Serbia


In the last few years, I – III –VI2 compounds have been intensively studied as the most suitable materials for various optoelectronic and photovoltaic devices. Recent studies have shown that for polycrystalline Cu(InGa)Se2-based solar cells conversion efficiencies of up to 19.5% can be achieved.1 One of possible ways to reach higher conversion efficiencies is formation of tandem cells, so that light from wider spectral range can be absorbed. Thereby, AgInS2 has been considered as a promissory candidate to make efficient CdS/AgInS2/CuInSe2 tandem solar cells, as the band gap energy of AgInS2 (AIS, 1.87 -2.01 eV (tetragonal-chalcopyrite type) and 1.98eV (orthorhombic)), is somewhat bigger than optimal energy value (1.45 eV).2

In a typical synthesis, Ag and In salts were mix with 1-dodecanethiol. The mixture was saturated with argon and subsequently heated to 240°C in order to induce reaction between components. Temperature was kept constant for a fixed time, Fig 1. Colloidal dispersions were then cooled to room temperature. The obtained dark red materials were washed and dried for XRD measurements or dispersed in toluene for optical characterization.

Fig. 1 XRD patterns of AgInS2 samples. For all samples both crystalline structures, tetragonal (T) and orthorhombic (O), are present, but their ratio varies with duration of synthesis. Also, in sample synthesized for 4h, peaks that originate from AgIn8S5 phase are present. Formation of such non-stoichiometric phases is characteristic of all I-IV-VI2 semiconductors.

Literature: 1. Z. Aissa, M. Amlouk, T. Ben Nasrallah, J.C. Bernède, S. Belgacem, 2007. Solar Energy

Materials & Solar Cells 91: 489-494. 2. M.L. Albor Aguilera, J.R. Aguilar Hernández , M.A. González Trujillo, M. Ortega López, G.

Contreras Puente 2007 Thin Solid Films 515, 6272-6275.

Acknowledgements: Financial support for this study was granted by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Project 172056 and 45020) and as a part of COST CM1101 and MP1106 actions.

20 25 30 35 0 5 50 55 60

20 25 30 35 0 5 50 55 60

t = 20h

T - Tetragonal AgInS2

O - Orthorhombic AgInS2

* - AgIn5S

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)

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t = 8h

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t = 30min


Effect of CTAB and CTAB in Combination with Hyaluronan on Human Cells

Marie Kalbáčová1, Martina Verdánová1,2, Filip Mravec3, Tereza Halasová3, Miloslav Pekař3*

1 Institute of Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague, Prague, Czech Republic

2 Faculty of Science, Charles University in Prague, Prague, Czech Republic 3 Materials Research Centre, Brno University of Technology, Brno, Czech Republic


Cetyltrimethylammonium bromide (CTAB) is a cationic surfactant which could be used for the drug delivery applications. One possibility of its preparation for a suitable delivery system is CTAB complexation with an oppositely charged polyelectrolyte, preferably from a family of biopolymers. Hyaluronic acid (usually in sodium form; hyaluronan) is an excellent example of a such bio-polyelectrolyte which is produced also in human body. Interactions between CTAB and hyaluronan and properties of resulting complexes were relatively well studied (Thalberg et al., 1991; Halasová et al., 2011). The cationic surfactants are known for their harmful effects on cells, probably due to their attractive interactions with negatively charged membranes which are subsequently damaged by the surface activity and solubilization properties of surfactants. On the other hand, binding of surfactant to polymer may suppress its solubility, i.e. the presence in the solution either in monomeric or micellar form, which could result in suppressed availability for undesired interactions with cell membranes. Cells possess specific receptors for hyaluronan which can thus serve as a carrier of CTAB micelles wrapped within its structure.

In this work, the effect of different concentrations of CTAB (in a range of 0.2 mM – 2 mM) on human osteoblasts was tested by a variety of methods to get a complex overview. All of the used methods confirmed the cytotoxic effect of CTAB, which could be however suppressed by the presence of hyaluronan (1 g/l) in the case of the lowest CTAB concentration used (0.2 mM). The effect of the presence of fetal bovine serum in a medium (general supplement of cell growth medium) on the system was also investigated. It was found that the cytotoxic effect of CTAB is even higher and cannot be inhibited by hyaluronan presence.

Literature:

1. Thalberg K., Lindman B., Karlström G., 1991. Phase behavior of systems of cationic surfactant and anionic polyelectrolyte: influence of surfactant chain length and polyelectrolyte molecular weight. J. Phys. Chem. 95: 3370-3376.

2. Halasová T., Krouská J., Mravec F., Pekař, M., 2011. Hyaluronan-surfactant interactions in physiological solution studied by tensiometry and fluorescence probe techniques. Colloids Surf. A, 391: 25-31.

Acknowledgements:

This work was supported by the COST action CM1101, project No. LD12068 and project No. CZ.1.05/2.1.00/01.0012 from ERDF, PRVOUK-P24/LF1/3, Faculty of Science - project GAUK no. 501212.


Cytotoxic and Anti-proliferative Effect of Poly( butyl cyanoacrylate) Nanoparticles on Normal and Tumor Cells in vitro

Milena Petkova 1*, Ralica Skrobanska 1, Alexander Evangelatov 1, Georgi Yordanov 2

1 – Sofia University “St. Kliment Ohridski”, Faculty of Biology, 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria

2 – Sofia University “St. Kliment Ohridski”, Faculty of Chemistry and pharmacy, 1 James Bourchier Blvd 1164 Sofia, Bulgaria

* - Milena [email protected]

Nanoparticles as drug delivery systems enable unique approaches for cancer treatment. Over the last two decades, a large number of nanoparticle delivery systems have been developed for cancer therapy, including organic and inorganic materials. Many liposomal, polymer-drug conjugates, and micellar formulations are part of the state of the art in the clinics, and an even greater number of nanoparticle platforms are currently in the preclinical stages of development. More recently developed nanoparticles are demonstrating the potential of these delivery systems by incorporating multifunctional capabilities and targeting strategies in an effort to increase their efficacy against the most difficult cancer challenges, including drug resistance and metastatic disease.

Widely used nanocarriers in medicine are poly(butyl cyanoacrylate) (PBCA) nanoparticles. They are the produced by emulsion polymerization of butyl cyanoacrylate, a substance used as a surgical glue. Despite its high biocompatibility, PBCA is a synthetic polymer, making it marginal as unnatural factor in the cellular environment. In this report we investigate the biologic effects of PBCA nanoparticles, stabilized with F68, on two cell lines: cervical cancer (HeLa) and corneal epithelium (SIRC). In general, our research includes determination of the cytotoxic effect of various concentrations of PBCA nanoparticles on the HeLa and SIRC cells. MTT test was used as cytotoxic assay. We examined the expression level of cyclin D, important regulator of cell cycle progression, in cells from the two cell types at a concentration of nanoparticles, toxic only to the tumor line. The biological effects of PBCA nanoparticles on the expression level of p53 and the degree of phosphorylation of the Akt were also investigated. The p53 tumor suppressor plays a central role in cell proliferation and death. It functions as a transcriptional activator of genes that block progression from G1 to S phase of the cell cycle. In the presence of extensive stress, p53 can direct the cell toward apoptosis. The PI3K/Akt pathway is well known to be a major cell survival pathway in many cancers. As a key molecule of this pathway, Akt regulates several downstream targets including the apoptosis-inducing protein, resulting in cell growth and survival. We also studied the correlation between the presence of apoptosis and quantity of p53 and phoAkt, after PBCA treatment, in normal (SIRC) and tumor (HeLa) cell lines.



Electrokinetic Studies of Cationic Polyelectrolyte Monolayers on Mica

M. Morga, Z. Adamczyk

Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences Niezapominajek 8, 30-239 Cracow, Poland


Adsorption of polyelectrolytes at solid/liquid interfaces is of great significance to many practical and natural processes such as formation of nanocoatings on textiles, nano-encapsulation for controlled drug delivery and release, cell adhesion, or protein and enzyme immobilization and separation. Despite of a vital significance of these processes, there are few experimental results concerning polyelectrolyte adsorption and monolayer formation under wet conditions obtained by in situ experimental techniques.

Physicochemical properties of cationic polyelectrolytes: poly(allylamine hydrochloride) (PAH), poly(ethylene imine) (PEI), and poly(dimethyldiallylammonium chloride) (PDDA), having molecular weights of 70,000, 75,000, and 120,000 respectively, were examined and compared. The bulk characteristics comprised the diffusion coefficient and electrophoretic mobility measurements determined as a function of pH (3.5 – 9) and ionic strengths (10-4 M to 0.15 M NaCl). These measurements allowed one to determine the amount of electrokinetic charge of the polyelectrolyte molecules and their isoelectric points. On the other hand, formation of polyelectrolyte monolayers on mica and their properties were investigated using the in situ streaming potential method. The measurements are quantitatively interpreted in terms of the three-dimensional (3D) electrokinetic model. Using this theoretical model one can determine inter alia the isoelectric points of polyelectrolyte molecules obtained in the self-assembly process. This enables one to gain clues on mechanisms of polyelectrolyte adsorption mechanisms driven by electrostatic interactions, which has significance to basic science.

Additionally, using this method, the stability of monolayers, evaluated via desorption kinetic measurements, was determined. The investigations showed that PAH molecules form the most stable monolayers, which can be used as supporting layers for particle deposition and multilayer formation.

Acknowledgments: This work was supported by grant: POIG.01.01.02.-12-028/09.


Streaming Potential Studies of α–Fe2O3/Ag Bilayers on Mica

M. Morga, Z. Adamczyk, M. Oćwieja



Electrokinetic properties of α–Fe2O3 (hematite)/silver nanoparticle bilayers on mica were thoroughly characterized using the streaming potential method. Hematite suspensions were obtained according to Matijevic method by acidic hydrolysis of ferric chloride, whereas silver nanoparticle suspensions were produced by a chemical reduction method in aqueous medium using sodium citrate. The size of the nanoparticles was determined by dynamic light scattering (DLS), and AFM. The size of the hematite and silver nanoparticles was 22 nm and 28.5 nm respectively. Both sols were stable within a long period of time, and ionic strengths varied between 10-4M – 10-2M NaCl. The dependence of the electrophoretic mobility and the zeta potential of the particles on ionic strength and pH was also investigated. For hematite particles it was positive for pH lower than 8.9 ( isoelectric point) and negative otherwise. On the other hand, for silver nanoparticles the electrophoretic mobility was negative for the entire range of pH (3-10) and ionic strength (10-4-10-2 M NaCl).

Both kinds of nanoparticles were used to obtain bilayers of α–Fe2O3/Ag under diffusion-controlled transport and investigated in situ using streaming potential method. Monolayer and bilayer coverage was quantitatively determined by AFM and SEM imaging, which allowed one to uniquely express the zeta potential of silver monolayers, in terms of particle coverage. Using SEM imaging, COMPO mode, enables one to not only qualitative but also quantitative determination of α–Fe2O3/Ag bilayer formation. Due to the fact that the hematite nanoparticles are positively-charged at acidic pH, no supporting layer was needed to perform the particle adsorption process. The zeta potential of α–Fe2O3/Ag bilayers was investigated in terms of the particle coverage using the streaming potential method. The dependencies obtained this way for various pH values were successfully interpreted in terms of three-dimensional electrokinetic model. On the basis of experiments, a universal calibrating graph was produced this way enabling one to determine hematite and silver bilayer coverage from the measured value of the streaming potential. Additionally, the stability of the α–Fe2O3/Ag bilayers (desorption kinetics) was also determined under in situ conditions using the streaming potential method.

Our experimental data proved that it is feasible to produce uniform and stable α–Fe2O3/Ag bilayers of well-controlled coverage. Such monolayers may find practical applications in biosensing, microelectronics, and catalysis.

Acknowledgments: This work was supported by grant: POIG.01.01.02.-12-028/09.


Nanodispersions as Micronutrient Carriers

Maria D.Hatzidaki1*, Damien Amadeï2, Fernando Leal Calderon2, Aristotelis Xenakis1

1 – Institute of Biology Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, Greece

2 – Institute of Chemistry and Biology of Membranes and Nanoobjects (CBMN), University of Bordeaux, France


The aim of the present work was to create stabilized nanodispersions, suitable as carriers of bioactive substances in food industry. To this concern, all examined components are biocompatible. Both microemulsions and nanoemulsions were considered.

In the first case, oils from different origins and categories of different, known surfactants have been studied. Vegetable oils as well as medium chain length triglycerides, fatty acid esters and also mixtures of these oils in different ratios have been tested (1,2). In order to reduce the polarity of the aqueous phase, which facilitates the development of the microemulsions, glycerol or propylene glycol has been added to the solutions. The system Miglyol 810/Ispopropyl Myristate: Lecithin/ Glycerol/ Ethanol successfully incorporated an aqueous phase consisting of distilled water.

In the second case transparent water-in-oil nanoemulsions based on Miglyol 810 were also successfully formulated either by matching the optical refractive index of the two immiscible fluids and/or by reducing the average droplet size below 200 nm through ultrasonification

The above nanoformulations were used as hosts of nutrients with specific activity. Namely phenolic compounds of olive oil, such as hydroxytyrosol and gallic acid were encapsulated in the aqueous nanodispersion. The systems developed, were examined for their microstructure using techniques like Dynamic Light Scattering (DLS) and Electron Paramagnetic Resonance (EPR). The effect of the micronutrients on the structure of the systems was also examined

The developed systems can be considered as effective vehicles of the selected micronutrients in food formulations

Literature:

1. Papadimitriou V, Sotiroudis T.G., Xenakis A., Langmuir, 2007, 23, 2071. 2. Patel N., Schmid U., Lawrence M., J. Agric. Food Chem., 2006, 54: 7817.


Kinetics of Silver Nanoparticle Release from Monolayers – Influence of Size, Ionic Strength, pH and Temperature

Magdalena Oćwieja*, Zbigniew Adamczyk, Maria Morga

Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland.


Silver nanoparticles exhibit a number of unique properties, which makes them a desirable material in such scientific disciplines as: biology, medicine, spectroscopy and catalysis, where they are used in the form of suspensions and films deposited on solid surfaces. Modifications of various materials by silver nanoparticles requires detailed studies on monolayers stability and kinetics of particles desorption. Because of the deficit of such systematic experimental results, the goal of this work was to determine the influence of particle size, ionic strength, pH and temperature on the release kinetics of silver nanoparticles form monolayers obtained by colloid self-assembly on PAH-covered mica.

A direct enumeration of particle coverage by the AFM and SEM proved an efficient tool for studying silver nanoparticles release kinetics. Using the RSA theoretical approach to interpret experimental results, the equilibrium adsorption constants Ka and the binding energy (energy minimum depth) for various physicochemical conditions were quantitatively determined, which is impractical using the classical adsorption methods.

Figure 1. Immobilization/release mechanisms of silver nanoparticles.

It was determined that, for particles of the average size of 15 nm and T = 298 K, the energy varied between -16.9 kT for ionic strength 0.1 M and –18.8 kT for ionic strength 10-4 M. For the largest nanoparticles (54 nm) the energy varied between -17.7 kT for ionic strength 0.1 M and –20.8 kT for ionic strength 10-4 M. These results suggest that the interactions between surface and nanoparticles are mainly controlled by electrostatic attraction between ion pairs. Therefore, in contrast to predictions of the mean-field DLVO theory, the energy minima were little dependent on ionic strength and size of particles. Furthermore, the decrease in the binding energy with the temperature was also observed, which contradicts the mean field theory. These experimental evidences indicate that the role of van der Waals interactions in the silver nanoparticle release processes from PAH covered mica surface was negligible. The kinetics of this process was governed by electrostatic interactions treated as discrete interactions among ion pairs rather than in terms of continuous theories of the electrical double layer.

Acknowledgments: This work was supported by grant:POIG.01.01.02-12-028/09 and Human Capital Operation Program, Polish Project No. POKL.04.0101-00-434/08-00.


Nanostructured CuxCe1-xO2-y and ZnxCe1-xO2-y materials as catalysts for the Water Gas Shift Reaction

Kelly Pemartin1, Henrik Kusar2, Conxita Solans1, Sergio A. Pérez-García3, Margarita Sánchez-Domínguez3, Magali Boutonnet2,*

1 - Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC) and CIBER en Biotecnología, Biomateriales y Nanomedicina (CIBER-BBN), Jordi

Girona 18-26, 08034 Barcelona, Spain. 2 - Royal Institute of Technology (KTH), School of Chemistry, Div. of Chemical Technology,

Stockholm, 10044, Sweden 3 - Centro de Investigación en Materiales Avanzados (CIMAV), Unidad Monterrey, Alianza

Norte 202, Parque de Investigación e Innovación Tecnológica, 66600 Apodaca, N.L., México. * - [email protected]

Low temperature water gas shift (WGS) reaction is an important catalytic step for the production of hydrogen for fuel cell applications. Cerium oxides have received a lot of attention as catalyst systems for the WGS reaction, most often prepared with precious metals. Ceria doped with transition metals have shown to be of great interest, and in particular Cu-Ceria catalysts have shown to perform excellently for the WGS reaction. WGS reaction was studied over two nanostructured CuxCe1-xO2-y catalysts and over two ZnxCe1-xO2-y catalysts with different loadings; these materials were synthesized by an oil-in-water microemulsion reaction method. The materials were characterized by X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM), BET, H2-TPR and XPS. A commercial low temperature WGS CuO-ZnO-Al2O3 catalyst was used as reference. The reaction was carried out in a plug-flow micro-reactor at a temperature range up to 400oC and atmospheric pressure with a feed composition of 1.8 mol % CO and 1.8 mol % H2O in nitrogen. The catalysts were calcined at both 400˚C and 650˚C.

Fig. 1. CO conversion obtained in WGS reaction: 1.8 mol% CO and H2O, SV= 5000 1/h over different catalysts The Cu0 2Ce0.8O2-y catalyst calcined at 400˚C showed good activity. The Cu0 1Ce0 9O2-y catalysts are less active and reached only slightly above 20 % CO conversion. The nanostructured ZnxCe1-

xO2-y catalysts showed poor activity for the water gas shift reaction at low temperatures.

Literature:

1. Sánchez-Domínguez M., Pemartin K., Boutonnet M. 2012. Curr. Opin. Colloid Interface Sci., 17, 297-305


Free Diffusion and Stress Dominated Spontaneous Fluctuations Characterized by XPCS in DPPC Monolayers with Nanoparticles

D. Orsi1, E. Guzman2, F. Ravera2, L. Liggieri2, B. Ruta3, Y. Chushkin3, L. Cristofolini1*

1 – Physics Department, University of Parma, Italy 2 – Istituto IENI-CNR, Genova, Italy

3 – European Synchrotron Radiation Facility, ESRF, Grenoble, France * - [email protected]

Nano-systems hold the promise of new technologies, but also raise new issues about the possible risks related to nanoparticles (NP). In this framework, pulmonary surfactant (PS) is known to be particularly affected by the interactions with NPs. In this study we focus on the effect of different types of NPs on monolayers of a model PS, namely DPPC, and in particular on the spontaneous fluctuation dynamics. Among the numerous papers addressing the PS-NP interactions, a very recent thermodynamic study seems to suggest that silica NPs have extensive mechanical effects that may originate from a bending of the lipid membrane around the NPs[1]. Previous investigations in a Langmuir trough by BAM, ellipsometry, and by surface dilational rheology methods, besides AFM of LB films [2,3] have shown the formation of mixed NP-DPPC layers whose mechanical, structural and phase characteristics differ significantly from those observed for pure DPPC.

We present here results from an investigation by Synchrotron based X-ray photon correlation spectroscopy (XPCS) in grazing incidence geometry from Langmuir monolayers. This technique -accessing the spontaneous fluctuations of a monolayer on the microscopic scale [4] - allowed us to individuate different dynamical regimes, as a function of the philic nature of the particles, and of the region of the isotherms. The relaxation times grow steadily with the pressure, to reach a plateau value that in the case of Silica NPs is independent of the particle size (in the range 18-120nm) while its dependence on the pressure mimics that of the size of the domains, which have been observed by epifluorescence microscopy on the same system. Interaction with hydrophobic NPs yields an even more intriguing phenomenology, with a pressure-driven transition from diffusion to a stress mediated relaxation, while retaining the general feature of the slowing down of the relaxation upon compression.

These results shall be discussed also in view of the interpretative models available at present for the surface rheology response of particle-amphiphiles layers, addressing the question of up to which extent nanometric inclusions alter lipidic monolayers.

Literature: 1. C Westerhausen, et al. , Biophysical Journal (2012) 102, 1032-8. 2. E. Guzmán, L. Liggieri, E. Santini, M. Ferrari, F. Ravera, J. Phys. Chem. C (2011)115, 21715-22. 3. E. Guzmán, L. Liggieri, E. Santini, M. Ferrari, F. Ravera, Soft Matter (2012) 8:3938-48 4. A. Madsen in “Soft Matter Characterization” (2012) Borsali Pecora ed.

D. Orsi L. Cristofolini G. Baldi A. Madsen Phys Rev Lett (2012)108, 105701 5. Name and First Name1, Name and First Name2, etc. Year. Title of Publication. Title of

Magazine Number: Pages.

Acknowledgements: We kindly acknowledge the ESRF for provision of beamtime, and COST action CM1101 for financial support


Engineering of Phosphatidylcholine – Based Solid Lipid Nanocarriers for Flavonoid Cocrystals Delivery

Urszula Bazylińska1 Magdalena Ciborowska1, Michał Sowa2, Ewa Matczak-Jon2, Kazimiera A. Wilk*1,

1 – Organic and Pharmaceutical Technology Group, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50370 Wrocław, Poland

2 – Inorganic and Structural Chemistry Group, Faculty of Chemistry, Wroclaw University of Technology, Wybrzeże Wyspiańskiego 27, 50370 Wrocław, Poland

* - kazimiera.wilk@ pwr.wroc.pl

Flavonoids, being low molecular weight polyphenolic compounds, are commonly found in vegetables, fruits, herbs, nuts and products of plant origin. Recognized health-prolonging effects, attributed mainly to their antioxidant, antitumor and anti-inflammatory properties account for increasing scientific interest. By virtue of low aqueous solubility and bioavailability, application as therapeutic agents in treatment and prevention of civilizational diseases is limited and their derivatization comes into focus. Cocrystallization as a method of obtaining new forms of APIs with improved physicochemical properties (e.g. solubility, stability, melting point) has rapidly gained attention over the last decade, yielding promising results. Encapsulation – from the other hand - is an efficient method of creating novel delivery systems for poorly water-soluble active agents in the technological and biopharmaceutical field [1]. Preparation of solid lipid nanoparticles (SLNs) loaded with novel flavonoid cocrystals can be promising method of encapsulation, yielding further improvement of solubility and release of cocrystallized polyphenolic cargo. The interest gained by the SLNs as alternative colloidal carrier systems to polymeric nanoparticles, liposomes or nanoemulsions is due to their reduced effect of ionic strength on stability, possible targeting by suitable chemical modification, good protection of encapsulated bio-active molecules, high encapsulation loads, absence of carrier bio-toxicity, avoidance of toxic organic solvents, ease of scale-up procedures and low cost. The aim of our contribution was to report on convenient methods of fabrication and characterization of biocompatible phosphatidylcholine-stabilized SLNs containing Polawax NF in the internal lipid phase. The present study was focused to determine and compare different SLNs preparation techniques i.e., solvent-diffusion and non-solvent approach, on encapsulation, improving solubility and sustained release of novel flavonoid cocrystals i.e., baicalein-nicotinamide [2] and myricetin-piracetam. DLS measurements confirmed particle diameter below 200 nm, while AFM and SEM its morphology and shape. Doppler electrophoresis provided a negative ζ-potential. UV-Vis was applied to determine both the encapsulation efficiency (about 90%), and the flavonoid cocrystal release kinetics from the SLNs prepared by various methods. Our results provide conclusions that the obtained SLNs might become suitable nanocarriers for long-sustained release of flavonoid cocrystals. Literature: 1. Bazylińska U, Pietkiewicz J, Saczko J, Nattich-Rak M, Rossowska J, Garbiec A, Wilk KA.

2012. Eur J Pharm Sci 47:406–420. 2. Sowa M, Ślepokura K, Matczak-Jon E. 2012. Acta Cryst C68:o262–o265. Acknowledgements: This work was financed by a statutory activity subsidy from the Polish Ministry of Science and Higher Education for the Faculty of Chemistry of Wrocław University of Technology and COST CM1101.


Fourier Transform Infrared Spectroscopy Analysis of Casein Embedded into Multilayer Films

Lilianna Szyk-Warszyńska*, Katarzyna Kilan, Anna Bratek-Skicki, Piotr Warszynski

Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, ul. Niezapominajek 8 30-239 Kraków, Poland


Casein represents one of the intrinsically unstructured proteins (IUP), which in their natural state does not adopt stable folded structure. That enables its easy integration into the polyelectrolyte multilayer films using the sequential adsorption or layer-by-layer (LbL) deposition technique [1]. Therefore, casein together with some biocompatible polycation, can form a membrane, which permeability can be controlled either by its thickness or by the external trigger (pH). Casein has a wide variety of uses, from being a major component of milk, use as a food additive, formulation thickeners to adhesives for labeling of glass containers. As a source of nutrition, casein supplies amino acids, carbohydrates, and two inorganic elements, calcium and phosphorus. Moreover, casein embedded in the multilayer structure preserves its ability to bind calcium ions [2]. In this work we focused on the structural changes of casein embedded in the multilayer films constructed with Poly-L-Lysine (PLL) or Poly-L-Arginine (PLAr) as polycations and α- and β-casein as polyanions. Films were built up on the Si/SiO2 surfaces and investigated by Grazing Angle FTIR in a dry state, or on germanium plates and investigated by FTIR-ATR as a wet films. To investigate the ability of casein in the multilayer to bind calcium ions, surfaces with adsorbed multilayer films were immersed in aqueous solutions of 20mM and 50 mM of CaCl2, CaCl2:Na2HPO4 (Ca:P=1:1) mixture and in the simulated body fluid (SBF) [3]. We found the difference between the native casein structure and that embedded in the multilayers films. Experiments demonstrated that adsorption of casein in the multilayer film cause its structuring, probably promoting formation of α-helices. Presence of calcium ions did not influence significantly the casein conformation.

Literature:

1. L. Szyk-Warszyńska, J. Piekoszewska, P. Warszyński, Formation and stability of poly-L-lysine/casein multilayers, Adsorption, 16 (2010) 241-248.

2. 2. L. Szyk-Warszyńska, C. Gergely, E. Jarek, F. Cuisinier, R. P. Socha, P. Warszyński, Calcium uptake by casein embedded in polyelectrolyte multilayer, Colloid and Interface Science A; 343 (2009) 118-126.

3. T. Kokubo, H. Kushitani, S. Sakka, T. Kitsugi and T. Yamamuro, Solutions able to reproduce in vivo surface-structure changes in bioactive glass-ceramic A-W, J. Biomed. Mater. Res., 24 (1990) 721-734

Acknowledgements:

This work was partially supported by was partially supported by the NCN grant NN 204 546 639, the Marian Smoluchowski Krakow Research Consortium - a Leading National Research Centre KNOW supported by the Ministry of Science and Higher Education and the COST Action CM1101.


Effect of Crosslinking by Calcium Ions on the Buildup and Permeabilityof Alginate Containing Multilayer Films

Katarzyna Kilan*, Lilianna Szyk-Warszyńska, Krzysztof Szczepanowicz, Piotr Warszyński



Multilayer polymer films, obtained by layer-by-layer (LbL) method are excellent candidates for coatings and membranes in molecular medicine applications. For such purpose they should demonstrate appropriate biological (biocompatibility) as well as physico-chemical (e.g. controlled thickness and permeability) properties. The aim of our work was to investigate the effect of alginate crosslinking induced by calcium ions on mass/thickness, viscoelastic properties and permeability of polymer multilayer films containing sodium alginate (ALG) as polyanion. Films were constructed by the LbL method with poly-L-arginine as the biocompatible polycation. The films’ mass and thicknesses were determined by QCM-D (quartz crystal microbalance with dissipation) and correlated with the results obtained by ellipsometry in dry state. We observed strong dependence of mass and thickness on the concentration of calcium ions in rinsing solution (Fig. 1.). Cyclic voltamperometry with electroactive agents of different molecular size was applied to determine the permeability of multilayers. We observed decrease in permeability of obtained films with increasing number of layers (that was indicated by the decrease in anodic and cathodic currents). Despite significant differences of mass/thickness of deposited films induced by presence of calcium ions in rinsing solutions, evident in QCM-D results, the considerable effect on the permeability of multilayers was not observed. Calcium ions. The effect of calcium ions in the conditioning solution on the structural changes of the multilayer after its formation was also investigated.

Fig. 1 Absorbed of multilayer of poly-L-arginine/ALG film formed with various rinsing solutions.

Acknowledgements:

This work was supported from the project Interdisciplinary PhD Studies "Molecular sciences for medicine" (co-financed by the European Social Fund within the Human Capital Operational Programme) and the Marian Smoluchowski Krakow Research Consortium - a Leading National Research Centre KNOW supported by the Ministry of Science and Higher Education and COST Action CM1101.


Single Drop Oscillation Experiments under Gravity and Short Term Microgravity Conditions

J. Krägel1*, V.I. Kovalchuk2, A. Javadi1, M. Karbaschi1, A.V. Makievski3, G. Loglio4, P. Pandolfini4, R. Miller1

1 – MPI Colloids and Interfaces, Potsdam-Golm, Germany 2 – Institute of Biophysical Chemistry, Kiev, Ukraine

3 – Sinterface-Technologies, Berlin, Germany 4 – University of Florence, Siesto, Italy


Particular experimental techniques are needed to understand short-term adsorption phenomena and high-frequency relaxations at liquid interfaces. A suitable technique for such studies is the capillary pressure tensiometry. Briefly, it based on the application of the Laplace equation to obtain dynamic interfacial tension from measurements of the capillary pressure across a droplet interface and of its radius of curvature. For very small almost hemispherical droplets it can be assumed that this radius is just the drop radius directly obtained from image analysis. However, under gravity conditions, there are rather strong limitations mainly caused by convections and interfacial deformations. The absence of gravity simplifies the kind of interfacial deformations and therefore experiments provide a much broader spectrum of dynamic interfacial data [1]. In this contribution we present results obtained with an experimental set-up developed for experiments to be performed at the drop tower facility in Bremen. The measuring principle is similar to the technique earlier developed for space shuttle flights (STS-95 and STS-107) [2]. In contrast to the long term microgravity experiments in space shuttles which run automatically after a programmed time schedule, the short term experiments in a drop tower allows the access and control of the experimental set-up short before the release of the capsule. The theoretical analysis of obtained experimental results will be discussed along with computational fluid dynamics simulation, performed for the optimization of experimental conditions, i.e. regarding hydrodynamic effects, capillary and cell design, drop size and other operational conditions. Experiments are also performed with a fast video technique in order to understand the range of applicability of the technique with respect to oscillation frequency and applied amplitudes.

Literature:

1. V.I. Kovalchuk, F. Ravera, L. Liggieri, G. Loglio, P. Pandolfini, A.V. Makievski, S. Vincent-Bonnieu, J. Krägel, A. Javadi and R. Miller, Capillary pressure studies under low gravity conditions, Adv. Colloid Interface Sci., 161 (2010) 102-114.

2. L. Liggieri, F. Ravera, M. Ferrari, A. Passerone, G. Loglio, R. Miller, A. V. Makievski, and J. Krägel. Results of microgravity investigation on adsorption and interfacial rheology of soluble surfactants from the experiment FAST onboard STS-107. Microgravity Science Technology, 18 (2006) 112-116.

Acknowledgements:

The work was supported by projects of the DLR (50WM1129), the DFG (Mi418/18-1) and by the COST-Actions CM 1101 and MP 1106.


Influence of Hyaluronan on Surfactant Micellization in Saline Solutions at Different Temperatures Studied by Isothermal Titration

Calorimetry

Jitka Krouská 1*, Miloslav Pekař 1

1 – Materials Research Centre, Faculty of Chemistry, Brno University of Technology, Purkyňova 118, 61200 Brno, Czech Republic


The present work focuses on the determination of the thermodynamic parameters (normalized reaction enthalpy, enthalpy of micellization) as well as the critical micelle concentration of two cationic surfactants CTAB and TTAB with and without hyaluronan in water and in 0.15 M NaCl solution at different temperatures (25, 30, 35 and 40°C). Moreover, the experiments were performed with hyaluronan of high and low molecular weight. For this purpose, isothermal titration calorimetry was used. The results showed the shift of the critical micelle concentration towards lower values which is caused by the repulsions of the polar head groups with counterions. It is in good agreement with other studies by Šarac et al. [1] and Beyer et al. [2].

Fig. 1 Hyaluronan structure [3]

Literature:

1. Šarac Bojan, Bešter-Rogač Marija. 2009. Temperature and salt-induced micellization of dodecyltrimethylammonium chloride in aqueous solution: A thermodynamic study. Journal of Colloid and Interface Science 338: 216–221.

2. Beyer Katja, Leine Dag, Blume Alfred. 2006. The demicellization of alkyltrimethylammonium bromides in 0.1M sodium chloride solution studied by isothermal titration calorimetry. Colloids and Surfaces B: Biointerfaces 49: 31–39.

3. Ribeiro Walkíria, Orfão Marta, Mata José Luís, Saramago Benilde. Behaviour of wetting films of sodium hyaluronate saline solutions. Journal of Colloid and Interface Science 317: 536–543.

Acknowledgements:

This work was supported by the COST action CM1101, project No. LD12068 and project No. CZ.1.05/2.1.00/01.0012 from ERDF.


Measurement of Interaction of Colloidal Drug Carriers Based on Polymeric Nanoparticles with Human Plasma Proteins by Surface

Plasmon Resonance

Jaroslav Katrlík 1*, Peter Gemeiner 1, Georgi Yordanov 2

1 – Department of Glycobiotechnology, Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia

2 – Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria


Surface plasmon resonance (SPR) is routinely used in study of protein - protein interactions, however, its use for study of interactions between proteins and nanoparticles is limited. Nanoparticles have a large potential for use in medicine, pharmacy and biology because their ability of specific and controlled interaction with targeted cells in organisms. On the other side, unwanted interactions of nanoparticles with individual components of the body (e.g. proteins) can cause many problems in the organism. In the case of use nanoparticles as drug carriers, the blood plasma proteins bind the surfaces of colloidal nanoparticles immediately upon their entry into an organism. The kinetics of this process is important factor playing a key role in affecting of biodistribution of the drug carriers. For the evaluation of such interactions we have used both free and epirubicin-loaded colloidal nanospheres of poly(butyl cyanoacrylate) as the model system of a colloidal drug carrier and the interactions with plasma proteins (albumin, fibrinogen, immunoglobulin G) were measured by SPR. The proteins were immobilized on the surface of polycarboxylate hydrogel SPR biochip and the measurements were carried out at various temperatures (25, 30 and 37°C). The calculated quantitative data could help to estimate the biological action of studied nanoparticles.

Acknowledgements: This work was supported by CMST COST Action CM1101.


Influence of Ionic Strength on Shear–thickening Properties of Hydroxypropylmethyl Cellulose/Sodium Dodecyl Sulfate Mixtures

Alena Tomšik, Jaroslav Katona *, Sandra Njaradi, Lidija Petrović, Brankica Marčeta, Jadranka Milanović

University of Novi Sad, Faculty of Technology, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia * - [email protected]

Mixtures of polymers and surfactants are commonly found in a range of products of pharmaceutical, cosmetic, and food industry. Interaction between polymers and surfactants influences different properties of these products, e.g. stability, flow properties, phase behavior etc. [1][2]. It has been reported that mixtures of hydroxypropylmethyl cellulose (HPMC) and sodium dodecyl sulfate (SDS) show shear–thickening properties when certain conditions are met i.e. molar mass of HPMC, the overlap parameter, concentration of SDS, and shear rate range. The shear thickening comes from HPMC–SDS complex formation. The objective of this work was to study the effects of ionic strength on shear–thickening flow behavior of HPMC/SDS mixtures. HPMC/SDS mixtures, composed of 0.70% wt. HPMC and SDS concentration ranging from 0.00% to 2.00% wt., were prepared in deionized water, in 0.01M and 0.05M NaCl solutions. Influence of shear rate on viscosity () and the first normal stress difference (N1) was investigated. It was found that on increase in ionic strength of the mixtures the onset of shear–thickening occurs at lower shear rates. In addition, the increase in N1 on increase in shear rate (N1/) becomes more pronounced when ionic strength of the mixtures is increased.

Literature:

1. Nystrom B, Kjoniksen, A.-L, Lindman B. 1996. Effect of temperature, surfactant, and salt on the rheological behavior in semidilute aqueous systems of a nonionic cellulose ether. Langmuir 12: 3233-3240.

2. Lapitsky Y, Kaler EW. 2006. Formation and structural control of surfactant and polyelectrolyte gels. Colloid Surf. A, 282: 118-128.

Acknowledgements:

This work was financially supported by Ministry of Education, science and technological development of Republic of Serbia grant No. III 46010/3.


Functional Coatings from Stimuli-Responsive Polymeric Micelles

Inna Dewald1*, Munish Chanana1, Julia Gensel1, Johann Erath1, Eva Betthausen2, Axel H.E. Müller2,3, Andreas Fery1

1 University of Bayreuth, Physical Chemistry II, D-95440 Bayreuth 2 University of Bayreuth, Macromolecular Chemistry II, D-95440 Bayreuth

3 Johannes Gutenberg University Mainz, Institute of Organic Chemistry, D-55128 Mainz * - [email protected]

Today, many objects of our everyday life consist of coated materials. Evidently, the usage of functional/responsive coatings has gained an increasing importance during the modern era of technology. The advantage of those materials is that they can adapt to their surroundings by changing their wettability and permeability as well as their adhesive, adsorptive, mechanical and optical properties.

In this work, we investigate the potential of responsive block copolymer micelles for this purpose. The use of block copolymer micelles has several advantages: Polymeric micelles can be stimulus-responsive and multi-functional on the single particle level, while coatings can be formed by simple physisorption.

Here, we present two pH-responsive systems based on this strategy:

(1) pH-sensitive ABC triblock terpolymer micelles with hydrophobic core/pH-sensitive shell/cationic corona [1] are adsorbed onto solid substrate resulting in a monolayer of micelles. By variation of solution pH, it is possible to reversibly switch the surface micelles’ charge density, swelling state and composition.[2] These active surfaces can be used as anti-fouling coatings which change their surface characteristics in response to cellular metabolism.[3]

(2) Using the layer-by-layer approach, the same micelles are included within multilayer films leading to coatings with novel internal double-end-tethered polyelectrolyte brush structures.[4] Due to the separation of the binding and the stimuli-responsive components within the layer-by-layer films, stable and highly swellable coatings with swelling degrees up to 1200% are observed.

Literature:

1. Betthausen E.2, Drechsler M., Förtsch M., Schacher F. H., Müller A. H. E.2,3, Soft Matter, 2011, 7, 8880-8891.

2. Gensel J.1, Betthausen E.2, Hasenöhrl C.1, Trenkenschuh K.1, Hund M.1, Boulmedais F.1, Schaaf P., Müller A. H. E.2,3 and Fery A.1, Surface immobilized block copolymer micelles with switchable accessibility of hydrophobic pockets, Soft Matter, 2011, 7, 11144-11153.

3. Gensel J.1, T. Borke, Pazos Pérez N.1, Fery A.1, Andreeva D. V.1, Betthausen E.2, Müller A. H. E.2, Möhwald H. and Skorb E. V., Cavitation Engineered 3D Networks and Their Application in Active Surface Construction, Adv. Mater., 2012, 24, 985-989.

4. Gensel J.1, Dewald I.1, Erath J.1, Betthausen E.2, Müller A. H. E.2, Fery A.1, Reversible swelling transitions in stimuli-responsive layer-by-layer films containing block copolymer micelles, Chem. Sci., 2013, 4, 325-334.


Foam Drainage on a Porous Substrate: Direct Numerical Simulations

Andrei Bureiko1, Nina Kovalchuk, 2,3*, Anna Trybala2, Victor Starov2

1 – Procter & Gamble, USA 2 – Department of Chemical Engineering, Loughborough University, UK

3 – Institute of Biocolloid Chemistry, Kiev, Ukraine * – [email protected]

Foams are omnipresent in our everyday life. They are widely used in food, cosmetics, pharmacy etc [1,2]. For many applications, particularly in pharmacy and cosmetics, the interaction of foam with substrate is of great importance. This interaction can affect, for example, the kinetics of the release of acting substances from foam and therefore have to be taken into consideration when looking for optimal formulations.

Often the surfaces where foam is applied are porous (skin, hair). To identify the methods to control the kinetics of liquid release in this case we performed direct numerical simulations of foam drainage on the porous substrate. The mathematical model developed combines the foam drainage equation with the equation describing the penetration of liquid in the model porous substrate of prescribed structure coupled with appropriate boundary conditions at foam/substrate interface.

The performed numerical simulations have shown that depending on the liquid viscosity, bubble size, foam height, substrate porosity and wetting conditions two different scenarios are possible – with and without the formation of continuous liquid layer between the foam and porous substrate. Kinetics of foam drainage and penetration of liquid into porous substrate is considered in details for both scenarios depending on the properties of foaming liquid and substrate.

Literature:

1. Kircik L.H., Bikobski J. 2012. Topical foam formulations. Vehicles Matter, Supplement to Practical Dermatology 1: 3-18.

2. Arzhavitina A., Steckel H. 2010. Foams for pharmaceutical and cosmetic application. Int. J. Pharmaceutics 394: 1-17.

Acknowledgements:

This research was supported by Procrtor & Gamble, USA, PASTA, European Space Agency, COST project CM1101.


Stability of Foam and Emulsion (oil/water/oil) Films from

INUTEC®SP1 and Polyoxyalkylated Dietylenetriamine Polymeric Surfactants Solution Mixtures

Hristina Petkova*, Khristo Khristov, Dotchi, Exerowa.

Institute of Physical Chemistry, Bulgarian Academy of Science, 1113 Sofia, Bulgaria * - [email protected]

The stability of foam and emulsion (oil/water/oil) films from INUTEC®SP1 and four (A, B, C, D) polyoxyalkylated dietylenetriamine polymeric surfactants mixture solutions is investigated.

INUTEC®SP1 is an inulin-based polymeric surfactant, synthesized by ORAFTI (Belgium) and industrially applied as an emulsion stabilizer.

A, B, C and D are products of Champion Technologies (USA). The molecule of each polymer consists of two parts: a more hydrophobic one, where polypropylene oxide (PPO) blocks are predominant and a more hydrophilic one, where polyethylene oxide (PEO) blocks are predominant. Surfactants A, B, C have a similar structure and belong to the group of the so-called “star-like” polymers, differing only in the number of polymeric branches: 4, 6 and 9 in the mentioned order. Surfactant D is of a dendrites type and its molecule consists of 4 to 6 primary and 2-3 secondary branches. Surfactant A is an industrially applied agent, while surfactants B, C and D have been recently synthesized.

At lower electrolyte concentration (Cel=10-3mol.dm-3NaCl) surfactants A, B, C and D act as antifoaming agents. The values of critical pressures of film rupture for films from mixture

solutions (P cr,f) are significantly lower then those of films from pure INUTEC®SP1. Surfactant C appears to be the best antifoaming agent. At higher electrolyte concentration (Cel=10-1mol.dm-

3NaCl) surfactant B is the best antifoaming agent while surfactants A and D act as foam films stabilizers.

All of the investigated surfactants act as de-emulsification agents. Values of P cr,f of emulsion films from mixture solutions are much lower than those obtained for films from pure

INUTEC®SP1.

The results show that depending on the conditions, surfactants А, B, C and D may act as stabilizers or destabilizers of thin films. This observation gives reason to believe that model studies could be used to predict the performance of polymeric surfactants studied as foaming/antifoaming or emulsification/deemulsification agents in real industrial processes.


Removal of Citrate-coated Silver Nanoparticles from Aqueous Dispersions Using Activated Carbon

Gospodinka Gicheva1*, Georgi Yordanov2

1 Department of Chemistry, University of Mining and Geology St. Ivan Rilski, 1700 Sofia, Bulgaria

2 Faculty of Chemistry and Pharmacy, Sofia University St. Kliment Ohridski, 1164 Sofia, Bulgaria

* - e [email protected]

Silver nanoparticles (Ag NPs), with sizes usually less than 100 nm, are the most widely used inorganic nanoparticles in commercial products, mainly because of their unique optical, catalytic and antimicrobial properties. Silver nanomaterials have found a wide range of different applications in many aspects of everyday life, such as medical products, textiles, house hold items (in fridges, air conditioning, vacuum cleaners, washing machines), paints, plastics, etc. The increasing number of different types and quantities of commercial products containing silver nanosilver products will certainly create a new type of nanowastes. Nanocomposite materials containing nanosilver may release nanoparticles and Ag(I) ions to the environment. The Ag-containing nanowastes can be released also into the environment from factories during the production of the commercial nano-products. Therefore, methods for management of Ag-nanowastes need to be developed.

Here, we report studies on the efficiency of activated carbon as adsorbent for manufactured water-dispersible silver nanoparticles. Nanoparticles of average size around 60 nm and negative zeta-potential were synthesized by reduction of Ag(I) ions with sodium citrate in aqueous medium. Activated carbon (Norit® CA1) designed for water purification was found to be an efficient adsorbent for silver nanoparticles. It was found that nanoparticle adsorption on activated carbon could be described by Freundlich and Langmuir isotherms. The presence of electrolytes favoured nanoparticle deposition on the surface of activated carbon. These studies could be interesting for deeper understanding of the mechanisms of interaction between nanoparticles and solid-liquid interfaces, for preparation of nanoparticle/carbon composite materials, as well as for designing of methods for removal of metal nanoparticles from contaminated water during treatment of nanowastes.



Resonance Growth of Giant Disclike Micelles in Mixed Surfactant Solutions Triggered by the Addition of Fatty Acids

Gergana S. Georgieva,1,* Svetoslav E. Anachkov,1 Peter A. Kralchevsky,1 Krassimir D. Danov,1 and Kavssery P. Ananthapadmanabhan 2

1Department of Chemical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, 1 J. Bourchier Blvd., 1164 Sofia, Bulgaria

2 Unilever Research & Development, 40 Merritt Blvd., Trumbull, Connecticut 06611, USA * - [email protected]

In previous studies, a synergistic growth of rodlike micelles at relatively low surfactant concentrations was found in binary mixed solutions of anionic and zwitterionic surfactants [1]. Recently, we found that the addition of lauric acid and other fatty acids to the solutions of cocamidopropyl betaine (CAPB) and sodium laurylethersulfate with one ethylene-oxide group (SLES-1EO), leads to a tremendous rise of viscosity of the aqueous solutions in a narrow vicinity of a given composition of this ternary mixture. Experiments with polarized light and NMR revealed that these viscous solutions are isotropic, i.e. we are dealing with micellar solutions, rather than liquid-crystalline phases. At the “resonance” composition of the ternary surfactant mixture, light scattering experiments have been carried out, which revealed that the micelles in these aqueous solutions are giant and have disclike shape, in agreement with previous observations. Interestingly, if the solutions are prepared with heavy water (D2O), the micelles are rodlike and smaller. For example, at a relatively low total surfactant concentration, 1 mM, the aggregation number of the investigated giant micelles is 4–6 thousand monomers in the case of rodlike micelles in D2O, and 67–100 thousand monomers in the case of disclike micelles in H2O. The experimental results are in good agreement with the theoretical laws for the growth of rodlike and disclike micelles, respectively.

Fig. 1 The “resonance” growth in viscosity is observed at a given fatty acid concentration.

Literature:

1. Christov N.C., Denkov N.D., Kralchevsky P.A., Ananthapadmanabhan K.P., Lips, A. 2004. Synergistic sphere-to-rod micelle transition in mixed solutions of sodium dodecyl sulfate and cocoamidopropyl betaine. Langmuir 20: 565–571.

disclike vs. rodlike micelles


Deposition of Metal Nanoparticles on Solid/Liquid Interfaces

Georgi Nikolov1*, Gospodinka Gicheva1, Georgi Yordanov2




Metal nanoparticles possess unique optical properties, which determine the great interest for applications in optics, electronics, catalysis and other research areas. Among them, the nanoparticles of noble metals are most studied because these nanoparticles are relatively more stable and easy to prepare. The deposition of metal nanoparticles on solid supports could be of interest for developing solid-based catalysts, materials for optoelectronics and other composite materials. The effective deposition of nanoparticles on solid surfaces could also be important for the development of methods for purification of water from dispersed nanowastes.

We prepared and characterized various in size silver nanoparticles, and studied their deposition on various substrates (inorganic oxides and polymeric resins). Some of the substrates were suitably modified in order to increase their affinity toward the nanoparticles. The effect of ionic strength on the nanoparticle stability and their deposition on the substrates was also investigated.



Epirubicin Loaded to pre-polymerized Poly(butyl cyanoacrylate) Nanoparticles: Preparation and in vitro Evaluation in Human Lung

Adenocarcinoma Cells

Georgi Yordanov 1*, Alexander Evangelatov 2, Ralica Skrobanska 2

1 Sofia University “St. Kliment Ohridski”, Faculty of Chemistry and pharmacy, 1 James Bourchier Blvd., 1164 Sofia, Bulgaria

2 Sofia University “St. Kliment Ohridski”, Faculty of Biology, 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria


Recent advances in pharmaceutical nanotechnologies have demonstrated the beneficial effect from formulating anticancer drugs in colloidal drug delivery systems. Nanoparticles of poly(butyl cyanoacrylate) (PBCA) are of particular interest in cancer chemotherapy since PBCA is a biocompatible, biodegradable, relatively stable material that is suitable for the entrapment of hydrophobic drugs at room temperature.

This report describes the preparation of epirubicin-loaded nanoparticles by loading of the drug in pre-polymerized poly(butyl cyanoacrylate) (PBCA) colloids, their physicochemical characterization, optimization of the preparation procedure and in vitro evaluation on human lung adenocarcinoma (A549) cells. The obtained nanoparticles were analyzed by means of scanning electron microscopy, dynamic light scattering and electrophoretic light scattering. Drug content, loading efficiency and in vitro drug release were also determined. The effect of the initial drug concentration on the average nanoparticle size, drug content and zeta-potential was studied. Experiments on cytotoxicity, drug uptake and intracellular localization of epirubicin were performed on lung adenocarcinoma (A549) cells. It was found that free epirubicin predominantly localized in the cell nucleus, while cytoplasmic localization was observed for nanoparticle-associated drug. Most probably, the drug-loaded nanoparticles entered into the cells via endocytotic mechanism and were localized into endosomes.



Synthesis, Characterization and Electrokinetic Properties of Poly(3-octylthiophene)/cuboid-TiO2 Hybrid Nanostructure

Evrim Sever 1*, Ozlem Erol 1, H.Ibrahim Unal 1 and Zekiye Suludere 2

1Gazi University, Chemistry Department, Smart Materials Research Lab. Ankara, Turkiye 2Gazi University, Biology Department, Ankara, Turkiye


Among the conducting polymers, poly(3-alkylthiophene)s are gaining great interest to scientists because of their environmental stability, easy processing, and having a wide range of electronic and optical properties which can be taken advantage of by modifying synthesis parameters [1]. Anatase TiO₂ and its various derivatives or composites have many extraordinary physical, chemical, electronic, electrochemical and photoactive properties with many application areas as a promising material in the literature [2]. In this study, TiO2 cuboids were successfully synthesized by hydrothermal process in HF(aq) starting from titanium tetraisopropoxide. After cuboid-TiO2 nanoparticles were surface modified with γ-aminopropyltriethoxysilane coupling agent and 3-thiophene acetic acid, respectively 3-octylthiophene monomer was chemically grafted on the surface of TiO2 cuboids via in-situ polymerization using FeCl3 as an oxidant. The structural, morphological and thermal properties of these nanoparticles were characterized using FTIR, 1H-NMR, XRD, TEM, SEM, TGA and elemental analysis techniques. Zeta-potential measurements were conducted to reveal the colloidal properties of the hybrid nanoparticles.

Fig. 1 TEM images of (a) cuboid-TiO2 and (b) P3OT/cuboid-TiO2 nanocomposite

Literature:

1. U. León-Silva, M. E. Nicho 2010 Poly(3-octylthiophene) and polystyrene blends thermally treated as coatings for corrosion protection of stainless steel 304. J. Solid State Electrochem. 14: 1487–1497.

2. H. C. Zeng 2011 Preparation and integration of nanostructured titanium dioxide. Current Opinion in Chemical Engineering 1: 11–17.

Acknowledgements:

We are grateful to the Turkish Scientific and Technological Research Council (111 T 637) and COST Action CM1101 for the support of this study.

(b) (a)


Interactions between poly(L-lysine) and poly(L-glutamic acid) inSolution and at Interfaces

Natali Nakić1, Jasmina Salopek1, Atiđa Selmani1, Maja Dutour Sikirić2 and Davor Kovačević1,*

1Division of Physical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia

2Ruđer Bošković Institute, Bijenička cesta 54, Zagreb, Croatia * - [email protected]

Mixing aqueous solutions of positively and negatively charged polyelectrolytes results in the formation of polyelectrolyte complexes, predominantly due to the electrostatic interactions between oppositely charged chains1. The formation of such complexes is influenced by the presence of various supporting electrolytes and by ionic strength. On the other hand, it is known that same factors significantly influence the process of formation and erosion of polyelectrolyte multilayers obtained by alternatingly dipping a substrate into, or flushing with, solutions that contain the negative and the positive polyelectrolyte, respectively2.

The influence of different salts as well as the effect of titration direction on polyelectrolyte complexes formed by mixing aqueous solutions of poly(L-lysine hydrobromide) (PLL) and poly(L-glutamic acid) (PGA) was investigated at t = 25 ºC and at ionic strength Ic = 0.001 mol dm-3. The methods used for the investigation of complex formation were conductometry and electrophoretic light scattering (i.e. zeta potential and particle size measurements). The obtained results were compared with results obtained by investigating the effects of salts on multilayer formation process. These experiments were based on alternate adsorption of same components (PLL and PGA) on silica using stagnation point optical reflectometry method. The comparison with various literature data3,4 was also performed. It has been shown that the behavior of polyelectrolyte complexes in solution is governed by the same principles as that of corresponding polyelectrolyte multilayers formed on metal oxides.

Literature: 1. Dautzenberg H., 1997. Polyelectrolyte complex formation in highly aggregating systems. 1.

Effect of salt: Polyelectrolyte complex formation in the presence of NaCl, Macromolecules, 30: 7810-7815.

2. Kovačević D., van der Burgh S., de Keizer A. and Cohen Stuart M.A., 2002, Kinetics of Formation and Dissolution of Weak Polyelectrolyte Multilayers: Role of Salt and Free Polyions, Langmuir, 18: 5607-5612.

3. Kolasinska M, Warszynski P., 2005, The effect of nature of polyions and treatment after deposition on wetting characteristics of polyelectrolyte multilayers, Appl. Surface Sci., 252: pp. 759-765.

4. Halthur, T.J., Claesson, P.M., Elofsson, U.M., 2004, Stability of polypeptide multilayers as studied by in situ ellipsometry: Effects of drying and post-buildup changes in temperature and pH, J. Am. Chem. Soc., 126: 17009-17015.


Effect of Measurement Cylinder Wettability on Foam Stability

Christophe .A.E. Hamlett1*, John Wallis1, Robert J. Pugh2 and David J. Fairhurst1

1School of Science and Technology, Nottingham Trent University, Clifton Lane, NG11 8NS, United Kingdom.

2Laboratory of Colloid and Surface Chemistry, University of Geneva, Switzerland. * - [email protected]

There are many methods used for measuring foamability and foam stability but few, if any, consider the effects of the wettability of the sidewalls of the vessels in which the foaming characteristics are measured. The wettability of the sidewalls will influence the extent to which the foam adheres to the sidewalls which could influence its stability.

In this study we investigate the effect of the wettability of the inside walls of sealed glass vials on both the foamability of both anionic and non-ionic surfactants and the stability of their resultant foams generated. Glass vials were functionalised to give a range of four different water contact angles (from hydrophilic to hydrophobic) before the surfactant solution was placed inside and shaken by hand to generate the foam. The foam stability over an hour was then monitored by videography.


Fast One-pot Synthesis of ZnS Nanoparticles in Aqueous Medium and Their Physicochemical Characterization

Bocho Bochev*, Georgi Yordanov

Sofia University “St. Kliment Ohridski”, Faculty of Chemistry and Pharmacy * - [email protected]

The study of semiconductor nanoparticles or quantum dots (QDs) has undergone enormous development over the last few decades [1]. The possible applications in light emitting diodes (LEDs), photovoltaic elements and fluorescent bioimaging make them attractive field of research [2]. Although zinc sulphide (ZnS) is one of the first semiconductors discovered [3], it still continues to be in the field of study as a relatively low toxic alternative of the well known cadmium-based QDs.

Here, we report the synthesis of nanosized semiconductor particles of ZnS prepared in aqueous medium from zinc sulphate and sodium sulphide. The obtained nanoparticles were observed by using transmission electron microscopy (TEM). Their optical properties were studied by using UV-vis absorbance spectroscopy, which allowed calculation of the average nanoparticle size from the exciton absorbance wavelength. The effects of concentrations of both sulphide and zinc precursors were studied, as well as the effects of overall concentration of precursors. We also studied the effects of aging of as prepared quantum dots and their precursors on the nanoparticle optical characteristics.

Literature:

1. Armand Alivisatos, 1996. Semiconductor clusters, Nanocrystals and Quantum Dots. Science 271: 933-937.

2. Xiaosheng Fang, 2011. ZnS nanostructures: From synthesis to applications. Progress in Materials Science 56:175-287

3. W.L. Davidson, 1948. X-ray diffraction evidence for ZnS formation in zinc activated rubber vulcanizates. Phys. Rev. 74:116-7



Formulation of Food Grade Microemulsions for Encapsulation of Bacteriocins

G. Kordali 1,2, V. Papadimitriou1*, M. Georgalaki 2, E. Tsakalidou 2, K. Papadimitriou 2, A. Xenakis1

1Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece.

2Laboratory of Dairy Research, Department of Food Science and Technology, Agricultural University of Athens


Bacteriocins are antimicrobial peptides or proteins produced by bacteria that kill or inhibit the growth of other bacteria. Bacteriocins produced by lactic acid bacteria used in food fermentations have attracted much attention due to the safe nature of the producer strains. For example, nisin is a bacteriocin produced by Lactococcus lactis that has been used as a food preservative for over 50 years now. In contrast to most bacteriocins, nisin has a relatively broad antimicrobial spectrum being active against several food spoilage and food borne pathogenic bacteria. Another example is macedocin, a bacteriocin produced by Streptococcus macedonicus that has been shown to be a particularly potent anti-clostridial agent [1]. The direct addition of purified or semi-purified preparations of bacteriocins in complex food matrices is not always a straightforward procedure. Bacteriocins are frequently sequestered by a variety of food ingredients and they are prone to proteolytic degradation. In this study, we aim to produce food grade microemulsions enriched with nisin or macedocin in order to be tested as the delivery medium of the bacteriocin in foods. In order to assure a long term stability of the ingredient it should be preferably located into the dispersed phase, whereas the continuous one could act as protective “buffer” area, in which various necessary additives could also be present. For this purpose, vegetable oils like olive oil and essential oils like limonene were examined as the continuous oil phase of the microemulsions. Food grade surfactants can be either natural phospholipids, such as lecithin or polyoxyethylene sorbitan esters. Mixtures of these surfactants at different mixing ratios were also examined. Food grade alcohols were also used in some systems to facilitate emulsification of the vegetable oil [2,3]. The phase behaviour of these systems was described by pseudo-ternary phase diagrams, which were determined at 25 oC. The effect of the presence of bacteriocins on the extent of the monophasic region was also examined. Particle size measurements of the bacteriocin containing microemulsions were performed using Dynamic Light Scattering (DLS) to ensure the formation of aqueous droplets at the nanoscale. Finally, the efficacy of the microemulsions enriched in bacteriocins to exert antimicrobial activity is tested in vitro and in food matrices.

Literature:

1. Georgalaki M.D., Van den Berghe E., Kritikos D., Devreese B., Van Beeumen J., Kalantzopoulos G., De Vuyst L., Tsakalidou E. Appl Environ Microbiol, 2002, 68, 5891-5903. 2. Papadimitriou V, Sotiroudis T.G., Xenakis A., Langmuir, 2007, 23, 2071-2077. 3. Kyriazi, Α. V. Papadimitriou, T. G. Sotiroudis, A.Xenakis. Eur. J. Lipid Sci. Technol 2013, DOI: 10.1002/ejlst.2012003


Method for Removal of Semiconductor Nanoparticles from Contaminated Waters

Antoniya Kaisheva1*, Gospodinka Gicheva1, Georgi Yordanov2*



* - dj [email protected]

Semiconductor nanoparticles (quantum dots) are one of the most exploited nanomaterials in the field of nanotechnology. Their unique optical and electronic properties determine their applications in bioimaging, cancer biology, photovoltaic elements, etc. Their vast application puts them among the highest ranking potential environmental pollutants. Their chemical composition includes well known health hazard heavy metals which combined with the toxicity due to their small size and well developed/reactive surfaces make it a priority to investigate a method for their removal from wastewaters.

This study considers the designing a method for the removal of water-dispersed semiconductor nanoparticles (quantum dots) by using different sorbents such as active carbon, silica, etc. Quantum dots were synthesized by wet chemical methods and were used as model pollutants. The sorption capacity of the different sorbents toward the nanoparticles was studied in static conditions in order to determine the most promising one for potential industrial application. The effect of the pH and ionic strength of the media was investigated since these are the most influential parameters regarding the purification of nanowastes from natural waters.



Protonation Mechanisms of Oligo(ethyleneimines) in Dissolved State and Substituted at Cellulose Backbone

Duško Čakara 1*, Melanie Nikolajski 2, Matej Bračič 3, Lidija Fras-Zemljič 3, Thomas Heinze 2

1 – Deprtment of biotechnology and Centre for micro and nano sciences and technologies, University of Rijeka, Croatia

2 – Macromolecular Chemistry, Centre of Excellence for Polysaccharide Research, Friedrich Schiller University of Jena, Germany

3 – Institute of Engineering Materials and Design, University of Maribor, Slovenia * [email protected]

The cluster expansion of the protonation free energy enables the resolution of the site-specific protonation patterns of weak oligoprotic molecules with electrostatically interacting sites1. In the present paper, this method is validated for the oligo(ethyleneimines) bound to the cellulose backbone. For this purpose, water-soluble aminocelluloses with a series of linear and branched oligo(ethyleneimine) moieties were synthesized, and their proton binding isotherms determined in the potentiometric titration experiments2,3. The microscopic speciation patterns for the whole series of aminocelluloses are obtained by invoking only a small number of physically significant cluster parameters, which are obtained by fitting the experimental proton binding isotherms. The comparison of the results for the oligo(ethyleneimines) substituted at the cellulose backbone, and those for their free dissolved counterparts, reveals that the cluster parameters reflect the chemical environment of the oligoamine moieties.

pH pH pH

Fig. 1 Microscopic protonation patterns for oligo(ethyleneimines) substituted at cellulose backbone.

Literature:

1. Borkovec Michal, Čakara Duško, Koper Ger J.M. 2012. Resolution of Microscopic Protonation Enthalpies of Polyprotic Molecules by Means of Cluster Expansions. Journal of Physical Chemistry B 116: 4300-4309. 2. Fras Zemljič Lidija, Čakara Duško, Michaelis Nico, Heinze Thomas, Stana Kleinschek Karin. 2011. Protonation behavior of 6-deoxy-6-(2-aminoethyl)amino cellulose: a potentiometric titration study. Cellulose 18: 33-43. 3. Čakara Duško, Nikolajski Melanie, Bračič Matej, Fras-Zemljič Lidija, Heinze Thomas. Site-specific Proton Binding of Cellulose Functionalized with Linear and Branched Oligoamines. in prep.

Acknowledgements: The authors kindly thank Professor Michal Borkovec from the University of Geneva for help with the statistical-mechanical calculations.

cost cm1101 workshop

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