physical chemistry and colloid science co 2+ pb 2+ cd 2+ interfaces in food science and...
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PHYSICAL CHEMISTRY AND COLLOID SCIENCE
Co2+ Pb2+Cd2+
Interfaces in food science and biotechnology
Polymers at interfaces
Strategic programme Colloids and interfaces
BiophysicalChemistry
Environmental physical chemistry
Work at physical chemistry and colloid science with bio-aspects
Wageningen UniversityLaboratory of physical chemistry and colloid scienceDreijenplein 6, 6703 HB Wageningen, the [email protected], [email protected]
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
Laboratory of physical chemistry and colloid science Strategic topic in phys. chem. and coll. sci. Biophysical chemistry Phys. chem. of food and biotechnology Polymers at interfaces Environmental physical chemistry
Approach:
-systematic experiments with a focus on understanding (we prefer to use model systems)
-theoretical modeling directed to understand experiments
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
1. Self-assembly of pluronic 121 polymersomes PEOn-PPOm-PEOn surfactants form unstable vesicles
for n ~5 and m~60 (L121) We stabilize the vesicles by a PETA network and
obtain stable nanocapsules with tunable size Below you see such capsules filled by fiber-forming
protein.
F. Li, T. Ketelaar, A.T.M. Marcelis, F.A.M. Leermakers, M.A. Cohen Stuart, E.J.R. Sudholter
"Stabilization of polymersome vesicles by an interpenetrating polymer network"
Macromolecules 40 (2007) 329-333.
AFM images
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
2. SCF modeling of self-assembly
Lipid membranes in bulk and at interfaces bending moduli, structure and thermodynamics
Vesicles in bulk and at interfaces Protein-like inclusions in membranes
We like to work on
-pores in membranes
-interaction of polycation with negatively charged membrane
-asymmetric interaction of objects with membrane
-steady-state membrane systems
-vesicle to micelle transition by way of adding surfactants to lipids
R.A. Kik, F.A.M. Leermakers, J.M. Kleijn
"Molecular modeling of lipid bilayers and the effect of protein-like inclusions"
Phys. Chem. Chem. Phys. 7 (2005) 1996-2005.
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
3. Self-consistent field modeling Core-shell particles with PE corona Janus micelles composed of tri-block
copolymers An-Bm-Cn with
A, C hydrophilic
B hydrophobic
We like to work on:
-fluctuation in micelle size driving force
-self-assembly driven by electrostatic interactions
-understand the formation of tubular vesicles
-do more work on micellar shape transitions in micelles with PE corona
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
4. Micelles formed by attraction of + and charges Generic idea is make micelles with water
soluble compounds by mixing anionic block and neutral block Mn-Am
cationic block and neutral block Pn-Bm
when AB > 0 Janus micelles can form
I.K. Voets, A. de Keizer, P. de Waard, P.M. Frederik, P.H.H. Bomans,
H. Schmalz, A. Walther, S.M. King, F.A.M. Leermakers, M.A. Cohen Stuart
"Double-faced micelles from water-soluble polymers"
Angew. Chem. Int. 45 (2006) 6673-6676.
PAA42-b-PAAm47
P2MVP42-b-PEO446
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
5. Protein-copolymer complexes
Enzyme encapsulation,targeting, controlling activity
++enzyme
- - -+ ++++++ ++++++
- - --
--- - -
+ +enzyme
- - --- -
++
0
20
40
60
80
100
120
140
160
0 0.2 0.4 0.6 0.8 1
mole fraction PAA42PAAm417
aver
age
inte
nsi
ty k
Hz
PAA-PAM + lysozym:
light scattering
++
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
6. Micelles made by complexation with reversible
polymers Metal-bisligand coordination complexes are self-
assembled supramolecules that have residual (negative) charge.
Admixing with oppositely charged copolymers gives hierarchical self-assembly
Cryo-TEM images of coacervate core micelles formed in the mixed systems a), f- = 0.5 PMVP41-PEO204/ Zn-L2EO4
b), f- = 0.5 A-B-A/ Zn-L2EO4 mixed system. f- is the negative charge fraction in the mixed system.
A-B-A= polyaminoacid block copolymer, A = neutral block, B = positively charged block
Yan, Y.; Besseling, N. A. M.; de Keizer, A.; Marcelis, A. T. M.; Drechsler, M.; Cohen Stuart, M. A. Angew. Chem. Int. Ed. 2007, 46, published on line Feb.2, 2007
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
7. Brushes: experiments and SCF models
Brushes as anti-fouling surfacesPEO, polysacharide (sweet)
Polydisperse polymer brushes
Proteins in polyelectrolyte brushes
released
PE brush + protein with patched surface charge
spontaneous uptake:attraction dominates
SCF theory
Fint
H
s=
[kBT/Lxl
]
a
F.A.M. Leermakers, M. Ballauff, and O.V. Borisov “On the mechanism of uptake of globular proteins by polyelectrolyte brushes: a two-gradient self consistent field analysis” Langmuir 2007 in print
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
8. Polypeptide synthesis by yeast cells
DSPDSPpolypeptide
template-mediatedpolypeptide synthesis by yeast cells
in bioreactor
template-mediatedpolypeptide synthesis by yeast cells
in bioreactor
integration in
yeast genome
gene(DNA template encodingstructural polypeptide)
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
8. Tri-block copolyelectrolytes from yeast
e+p
m+p
e+n
m+n
+++ +++ - - - - - -
+++ +++ - - - - - -
+++ +++ - - - - - -
+++ +++ - - - - - -
pp pp
pp pp
n n
n n
pp pp
pp pp
n n
n n
e-p
m-p
e-n
m-n
code:code:
-available on gram scale
-homo-disperse, chiral and pure
-pH responsive gel formation (driven by -sheet formation)
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
9. Measurements of forces by colloid probe AFM We have an interest in measuring forces on the nanoscale-depletion forces
-in non-adsorbing polymer systems-in equilibrium polymer systems
-deformation of vesicles (nano-capsules)-electrostatic interactions, -polymer mediated forces-effect of surface modification.
EHUT + some DHUT
Silica+C18
cyclohexane
W. Knoben, N.A.M. Besseling, M.A. Cohen Stuart
"Long-range depletion forces induced by associating small molecules"
Phys. Rev. Lett. 97 (2006) 068301/1-4.
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
10. Summary experimental
SCF-modeling (and a little bit MC simulations) Strong in thermodynamic analysis Strong in electrified interfaces Scattering (light, neutrons, xrays) Reflectometry (dynamic adsorption studies)
/ellipsometry Calorimetry AFM including colloidal probe Titrations and other analytical tools, surface
characterisation Microscopy (light, confocal, TEM …) NMR Langmuir trough
PHYSICAL CHEMISTRY AND COLLOID SCIENCE
10. Summary systems
Self-assembly in aqueous systems based on hydrophobic driving force electrostatic driving force metal-ligand mediated assembly with help of polymer network
Applications are bio-inspired responsive systems preference to study equilibrium systems interest in steady state conditions
Open eye for applications