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3D Printing of Bipolymers
Additive manufacturing (AM) techniques
• AM techniques include extrusion (FDM, 3D dispensing, 3D fiber deposition,
and 3D plotting), vat photopolymerization (stereolithography), powder
bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D
printing), sheet lamination (LOM) and 3D bioprinting
• FDM (fused deposition modeling): the most commonly used AM technique.
• While FDM is limited to extrusion of thermoplastics at elevated
temperature, 3D (micro) extrusion enables 3D deposition of many other
classes of materials including thermosets, rubbers, polyurethanes,
silicones, organic and inorganic pastes, polymer latex, plastisols,
biomaterials, hydrogels, various functional polymers, and even
biologically active ingredients and living cells.
(1) Samuel Clark Ligon , Robert Liska, Jürgen Stampfl, Matthias Gurr, and Rolf Mülhaupt, Polymers for
3D Printing and Customized Additive Manufacturing, Chem. Rev., 2017, 117 (15), pp 10212–10290
(http://pubs.acs.org.libproxy.aalto.fi/doi/10.1021/acs.chemrev.7b00074)
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Technologies for 3D printing.
The basic principle of 3D printers is building objects layer by layer
Ad van Wijk & Iris van Wijk. 3d Printing With Biomaterials, Towards a Sustainable and
Circular Economy. (http://www.biobasedplastics.nl/wp-content/uploads/2015/02/3D-printing-
with-biomaterials.pdf)
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http://ac.els-cdn.com.libproxy.aalto.fi/S0032386116310461/1-s2.0-S0032386116310461-main.pdf?_tid=618dab44-
dfc7-11e6-a358-00000aacb361&acdnat=1484995991_aadebf9826348d9e87927f36a595e69e
https://repositorio.unican.es/xmlui/bitstream/handle/10902/6694/376365.pdf?sequence=1
https://airwolf3d.com/product-category/3d-printers/
Fused Deposition Modelling (FDM):widely used cheap and convenient 3D-
manufacturing method.
Image of fused deposit modeling
http://www.custompartnet.com/wu/3d-printing
Powder bed and inkjet head 3D printing
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Synthesis of biodegradable photocrosslinkablepolymers for stereolithographybased 3Dfabrication of tissueengineering scaffolds
and hydrogels, (https://aaltodoc.aalto.fi/handle/123456789/18252 ) here (hyperlink)
• Polymer resin needs to be in liquid form
• In SLA the liquid polymer resin is
hardened with light.
• The structure and material properties
needed depends on the target product
Schematic picture of SLA apparatus (1)
Stereolithography, SLA
• Exposure time How fast the material solidifies • Layer thickness• liftoff distance How viscose the material is
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Biopolymers used
for 3-D printing
Polymers are by far the most utilized class of materials for AM.
The range of polymers used in AM encompasses thermoplastics, thermosets,
elastomers, hydrogels, functional polymers, polymer blends, composites,
and biological systems.
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(1) European Bioplastics (http://www.european-bioplastics.org/)
(2) Wijk, A. & Wijk, I. 3D PRINTING WITH BIOMATERIALS TOWARDS A SUSTAINABLE AND
CIRCULAR ECONOMY, IOS Press, Neatherland, 2015, 86p. DOI 10.3233/978-1-61499-486-2-i
(3) Material Data Center (https://www.materialdatacenter.com/bo/standard/)
Bioplastics in 3-D printing
Bioplastics can be (a) biodegradable or (b)
bio-based or belong to both categories.(1)(2)
Thermoplastics are commonly used in 3D
printing. The most used is polylactid acid
(PLA) which belongs to both of the
categories.(2)
Examples from other plastics for 3D printing:
(a) PCL,
(b) PA-11, TPC, TPS, and
(a)&(b) PLLA, PLGA.(1)(2)(3)
The division between biobased and biodegradable (1)
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Biodegradable PCL(polycaprolactone) -scaffolds for tissue engineering
PVOH (polyvinyl alcohol)- multilayer applications (e.g.
films)
PTT (poly(propylene fumarate) -scaffolds for tissue
engineering
Polycaprolactone (PCL), FDM and Stereolitography
(SLS)
PA 11, PA 12 (biodegradable?)
Poly(glycolic acid) (PGA)
Gelatin methacrylate
Polypropylene fumarate (PPF), SLS
Polyethylene Glicol (PEG)
Polybutylene terephthalate (PBT), FDM
PGA (Polyglykol acid) -absorbable sutures
PCL (Polycaprolactone)-long term implants
PA (Polyanhydride) -drug delivery
PPF (polypropylene fumarate), POE (polyorthoesters),
PU (polyurethanes), PPy (polypyrroles), PDS
(polydioxanones),
Acrylated polyglycerol sebacate (Acr-PGS)
Acrylic-based resin (FullCure®720).
Bio-based• PHB (poly(3-hydroxybutyrate))-porous structures
• PLA (polylactic acid) -e.g. in biomedical devices,
laboratory equipment, FDM
• Poly (D,L-lactide) (PDLLA), SLS
• Hydrogels: Alginate, Agar, Gelatin,
Nanocellulose, Fibrinogen, Agarose, Alginate, K-
Carrageenan, Chitosan, Chondroitin Sulfate,
Dextran, Elastin, Fibrin, Gellan Gum,
Hyaluronan, Methylcellulose, Hyaluronic Acid,
Starch.
• Lignin
• Soy protein, Collagen, Gelatin,
• Poly(lactate/butanediol/sebacate/itaconate)
(PLBSI)
• Poly (lactic) acid (PLA) used in FDM-scaffolds
• Poly (D,L-lactide) (PDLLA) used in SLS
Natural polymers
• Hydrogel-forming biopolymers are
suitable for 3D printing
• Natural polymers in combination with
water-based binders has shown to
be promising for use in direct 3D
printing
• Solidification upon extrusion is a
challenge when natural biopolymers
are 3D printed
• Biopolymers are often 3D printed in
liquid media (electrostatic
interactions between the biopolymer
and the liquid media may be a
problem)
Important polymer properties
• Processing
• Rheology (1)
• Transition temperatures (e.g.
melting) (1,2)
• Product
• Mechanical properties (3)
• Biodegradation (2)
• Biocompatibility (2)
3D-printing often for medical
applications
• Customisable, personal products (1)
• Biodegradability enables temporary
use (2)
• Regrowth of tissue
(3) Patricio, T. et al. 2014 (http://www.emeraldinsight.com.libproxy.aalto.fi/doi/full/10.1108/RPJ-04-2012-0037)
(4) Dávila, J.L. et al. 2015 (http://onlinelibrary.wiley.com.libproxy.aalto.fi/doi/10.1002/app.43031/full)
(5) Yao, Q. et al. 2015 (http://link.springer.com.libproxy.aalto.fi/article/10.1007%2Fs10856-014-5360-8)
PLA (Polylactid acid)
https://ultimaker.com
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Poly(lactic acid) or polylactide (PLA), aliphatic polyester
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Structure/Production method:
• Bio-based monomer (lactic acid) by fermentation, followed by polymerisation
Current bulk producers
• Cargill Dow (Nature Works)
• ADM
• PURAC
• GalacticSelling price:
• 1,50‒2,00 €/kg
• 15 years ago: >10 €/kg
Poly(lactic acid) and polylactide (PLA) Source: Niaounakis M. (2014)
(6) Wolf O. et al. (2005): Techno-economic Feasibility of Large-scale
Production of Bio-based Polymers in Europe [6]
(7) Niaounakis M. (2014): Biopolymers: Processing and Products ([7])
Production:
• Fermentation to lactic acid monomers
• Polymerization to poly lactic acid
Pro:• Good biocompatibility• Good process ability • Biodegradable &
Biobased• Exact 3D-printability (2)
Con:• Brittleness• Hardness• Odure• Expensive (3)
(1) Siegma Aldrich, (2018). (Link)
(2) Wolf O. et al. (2005): Techno-economic Feasibility of Large-scale (Link)
(3) Winter et al., (2017): Residual wood polymers facilitate compounding of microfibrillated cellulose with poly(lactic acid) for 3D printer filaments (Link)
• PLA can be used in many applications and
modified with different compounds,
copolymerizations and blends.
• 3D printing can reduce the manufacturing cost
of smaller batches when no molds are needed.
• The possibilities in the medical field are
endles.
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Properties of PLA required for FDM
• Thermoplastic
• Tg: 55-65 [C] (rel. low)
• Melting point: 120-170 [C]
• Nozzle temperature around 180 C, lower than ABS
• Printing Temp.190-240 [C]
• Melt flow rate: 2.2 g/10 min.
• Density 1.25 [g/cm3] (PET: 1.34)
Further Properties
• Native biocompatibility
• Bio-based
• Biodegradable
• Blends: PLA/PCL, PLA/PHA, PLA/starch…
• Technical substitution potential: PMMA, PA, PET, PP
Fused deposition modelling schematic
Source: Chia H.N. et al. (2015)
(6) Wolf O. et al. (2005): Techno-economic Feasibility of Large-scale Production of Bio-based Polymers in Europe [6]
(7) Niaounakis M. (2014): Biopolymers: Processing and Products ([7])
(8) Song Y. et al. (2017): Measurements of the mechanical response of unidirectional 3D-printed PLA [8]
(9) Chia N. H., Wu M. B. (2015): Recent advances in 3D printing of biomaterials [9]
(11) Serra T. et al. (2012): High-resolution PLA-based composite scaffolds via 3-D printing technology [11]
(12) Wang Z. et al. (2017): Preparation of 3D printable micro/nanocellulose-polylactic acid (MNC/PLA) composite wire rods with high MNC constitution [12]
(14) Bose S. et al. (2017): Additive manufacturing of biomaterials [14]
Poly(ε-caprolactone)
• Biodegradable polyester
• Semicrystalline polymer
• Melting temperature is higher
than body temperature, high
toughness
• Degrades slowly (among
polyesters)
• Useful for biomedical matierials
due to phisycal and biological
properties
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M. Abedalwafa, F. Wang, L. Wang, C. Li Biodegradable
PCL for tissue engineering applications: A review
Polycaprolactone
• Synthetic: Homogeneity, quality and
purity
• Thermoplastic & good rheological
properties(1)
• Relatively low melting point (~60 C)(1,2)
= easier processing (melt extrusion)
• Biodegradable and biocompatible(2)
• Good mechanical properties(3)
(1) Patricio, T. et al. 2014 (http://www.emeraldinsight.com.libproxy.aalto.fi/doi/full/10.1108/RPJ-04-2012-0037)
(2) Dávila, J.L. et al. 2015 (http://onlinelibrary.wiley.com.libproxy.aalto.fi/doi/10.1002/app.43031/full)
(3) Yao, Q. et al. 2015 (http://link.springer.com.libproxy.aalto.fi/article/10.1007%2Fs10856-014-5360-8)
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(1) 3D Printing of Polycaprolactone Scaffolds
(2) In vivo biocompatibility and biodegradation of 3D-printed porous scaffolds based on a hydroxyl-functionalized
poly(ε-caprolactone
(3) 3D Printing Polymers with Supramolecular Functionality for Biological Applications
(4) 3D Printing Polymers with Supramolecular Functionality for Biological Applications
Low melting point allows for ease of 3d-Printing.
Is biocompatible, no toxic effects in the body and
is degraded slowly in the body allowing natural
tissue to replace it
Flexibility of material makes it ideal for structures
such as blood vessels and ligaments.(1)
One disadvantage is the high hydrophobicity limits
cell adhesion and degradation. Treatment to
cause hydroxylation of the PCL backbone can
mitigate this issue.(2)
High molecular weight means only extrusion 3D-
printing possible(3)
PCL as a biocompatible polymer in 3D-printing
Material properties of PCL
PCL scaffold transplanted in the gap
between the heads of ulna bone. [4]
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(1) Small Diameter Blood Vessels Bioengineered From Human Adipose-derived Stem Cells
(2) Polymer structure-property requirements for stereolithographic 3D printing of soft tissue engineering scaffolds
(3) In vivo biocompatibility and biodegradation of 3D-printed porous scaffolds based on a hydroxyl-functionalized
poly(ε-caprolactone
(4) 3D Printing Polymers with Supramolecular Functionality for Biological Applications
3D printing of biopolymers allows the creation of
personalized tissue scaffolds.
Allows for creation of structures specific for the
injury/condition the patient has.
Cells are implanted then infiltrate and adhere to
the porous PCL structure created.(2)(4)
PCL is slowly broken down over time by
macrophages, replaced with implanted cells.(3)
Breakdown is non toxic over the timescale it
occurs.(2)
3d printed PCL based blood vessel
(top) and antibody stains showing
integration of vascular tissue
below.(1)
PCL based tissue scaffolds
Nanocellulose
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Direct Ink Write (DIW) 3D Printed Cellulose Nanocrystal Aerogel Structures6
Polymer properties
High elastic modulus (110-220GPa), high strength
due to crystallinity, light weight, low density,
sustainability, biocompatibility, biodegradability,
recyclability, abundance in nature7
Flexibility allows to construct custom structures
which hold their form due to high Young’s
modulus.6
Challenges
o Increased concentration of CNCs leads to
higher viscosity which increases pressure
during the gel deposition through direct ink
write.
o Material brittleness can lead to structure
collapse during cell incorporation and growth.
(can be fixed with cross-linking with Kymene)
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(6) https://doi.org/10.1038/s41598-017-07771-y
(7) https://doi.org/10.1039/c0cs00108b
http://cellulosefromfinland.fi/3d-printing-of-cellulose-based-materials/
(5) M.I Santos. I. Pashkuleva. C.M. Alves. M.E. Gomes. S. Fuchs. R. E. Unger. J. Mater. Chem., 2009,19, 4091-
4101 (http://pubs.rsc.org.libproxy.aalto.fi/en/Content/ArticleLanding/2009/JM/b819089e#!divAbstract)
(6) Filipa A M M Gonçalves, Biofabrication 6 (2014) 035024 (14pp)
(http://iopscience.iop.org.libproxy.aalto.fi/article/10.1088/1758-5082/6/3/035024/meta)
• The main application of 3D bioprinting is human cartilage
tissue, for instance, the human ears.
• The nanofibrilar cellulose reinforced alginate provides the
material enough viscosity. And crosslinking provides less
shape deformation.
• To improve the shape fidelity of the alginate, NFC could be
involved as the main component.
Small grid printed with
(C1) 3% alginate
and (C2) 2.5% NFC.
(C3) Small grid of
printed and cross-
linked. [10]
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Figure 1. CNC gel structures at (a) 11.8, (b) 15, (c) 20, and (d) 30wt%. https://doi.org/10.1038/s41598-017-07771-y
Producing CNC aerogels with controllable porosity allows for its application in
tissue engineering because of the open cell type porous structures. Solvent
absorption, cell seeding medium infusion, oxygen permeation, nutrient transport,
cell growth, or metabolic waste removal is thus possible.
Great potential for 3D printing, especially when combined with strength additives.
Chitosan
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(1) (http://www.sciencedirect.com/science/article/pii/S0734975011000061)
(2) (https://pdfs.semanticscholar.org/af57/fa5a2b237174301b9b2740adbbe531a4a527.pdf)
(3) (http://www.sciencedirect.com/science/article/pii/S0734975009001852)
(4) (http://www.sciencedirect.com/science/article/pii/S0144861710003589)
(5) (http://www.mdpi.com/1660-3397/13/8/5156/htm)
Chitosan
Properties• Derative of Chitin,
• Abundant natural polymer next to
cellulose
• Linear,Reactive mino group,
• Crystalline,
• Insoluble in water,
• Renewable,
• Cationic nature
• Found in Insect, Shrimps, Crabs, Fungi,
Oysters, Shellfish,
• Biocompatible,Biodegradable,Non-
toxcic
Pros
• Minimal foreign body reaction.
• Antibacterial nature.
• Molded in different structures.
• Excellent bioestimulation.
• Good degradation rate.
Cons
• Chitosan decompose (>220ºC). May
not give the desired mechanical
properties when trying to print stable
composite structures.
Challenges in processing• High viscosity
• Poor/low solubility
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(1) (http://www.sciencedirect.com/science/article/pii/S0734975011000061)
(2) (https://pdfs.semanticscholar.org/af57/fa5a2b237174301b9b2740adbbe531a4a527.pdf)
(3) (http://www.sciencedirect.com/science/article/pii/S0734975009001852)
(4) (http://www.sciencedirect.com/science/article/pii/S0144861710003589)
(5) (http://www.mdpi.com/1660-3397/13/8/5156/htm)
Main application and its performance
Application:• Tissue enegineering,wound dressing,
• durg delivery,organ regeneration,
• Water treatment-waste separation membrane,
• Biosensor
• Cosmotics
Performance: Example-wound dressing1
• Promot tissue growth,
• Anti-fungal, anti-bacterial, permeable to oxygen,
• Facilitate cell attachment and maintain,
• Helps in blood clotting,
• Reduce pain, accelerate wound healing and scar prevent
• Accelerate repair of different tissue, regulate secretion of inflammatory
Figure 3. Wound dressing 1
Alginate
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Alginate Hydrogels
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Alginate worms
Cross-linked calcium alginate hydrogel (http://people.clarkson.edu/~amelman/alginate_hydrogels.html)
Poly(Glycolic Acid), PGA
(1) 海藻酸鈉_百度百科(https://baike.baidu.com/item/海藻酸钠)
(2) 3D-Printed Biopolymers for Tissue
Engineering Application
(https://www.hindawi.com/journals/i
jps/2014/829145/
(3) https://biomeder.com/3d-printing-
strand-bioink/)(4) 聚乙醇酸_百度百科
(https://baike.baidu.com/item/聚乙醇酸)
Low molecular weight PGA was already
synthesized 40 years ago, by ring- opening
polymerization of DL-Lactide and glycolide.
However, the Mechanical strength of it wasn’t
enough to create more solid structure, nor
materials for 3D printing, thus, low molecular
PGAs are normally used in sutures.
Fortunately, when molecular weight of PGA is
up to 20000 ~ 145000, the polymer can be pull
into fibrous status, and can make the
arrangement of the molecules inside be
directional, which increase the strength of the
polymer, and allows it to form into different
shapes.
PGA
(5) Structure-Processing-Property Relationship of Poly(Glycolic
Acid) for Drug Delivery Systems 1:Synthesis and
Catalysis(https://www.hindawi.com/journals/ijps/2010/65271
9/)
(6) http://china.chemnet.com/product/pclist--
%BE%DB%D2%D2%B4%BC%CB%E1--0.html
Although low molecular weight PGAs has
a lower mechanical strength and is also
easy to degrade, which cannot be used
in 3D printing, there is still a lot of ways
to increase the mechanical strength, for
example self-reinforcement.
Due to the low mechanical strength,
PGAs are normally used as Sutures in
surgeries, but not as 3D printing material,
however, with the immensely increased
property, it become a possible option for
PGA to be apply as 3D printing.
PGA
Starches and other polysachharides(Gellan Gum)
[2] Li, Xiaoming, et al. "3D-printed biopolymers for tissue engineering application." International Journal of Polymer
Science 2014 (2014).
6] Lam, Christopher Xu Fu, et al. "Scaffold development using 3D printing with a starch-based polymer." Materials
Science and Engineering: C 20.1 (2002): 49-56.
Plastarch material (PSM)• Plastarch material is composed of PLA grafted onto
starch nanoparticles. It has the basic processability of
PLA but increased mechanical strength and is no
longer hydrophobic like mere PLA. [4]
• Plastarch can be manufactured with the same
equipment as more common plastics. [4]
• Being starch-based, the production of PSM competes
with food production. [5]
(4) García, Lamanna, D’Accorso, Dufresne, Aranguren & Goyanes: Biodegradable materials from grafting of modified PLA onto starch
nanocrystals; Polymer Degradation and Stability;
Volume 97, Issue 10, October 2012;
(http://www.sciencedirect.com/science/article/pii/S0141391012001103)
(5) Barker & Safford: Industrial uses for crops: markets for bioplastics (https://cereals.ahdb.org.uk/media/408426/pr450-final-project-
report.pdf)
[6] Lam, Christopher Xu Fu, et al. "Scaffold development using 3D printing with a starch-based polymer." Materials Science and
Engineering: C 20.1 (2002): 49-56.
(7) ECO Products: PSM Cutlery (https://www.ecoproductsstore.com/plant_starch_cutlery.html)
Although usually biodegradable,
PSM items are not recyclable. [7]
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(1) Kirchmajer, D. M. et al. An Overview of the Sustainability of Hydrogen-forming Polymers for Extrusion-based 3d-printing. 2015.
(http://pubs.rsc.org.libproxy.aalto.fi/en/content/articlepdf/2015/tb/c5tb00393h)
(2) In het Panhuis, M. et al. Inkjet Printed Water Sensitive Transparent Films for Natural Gum-carbon Nanotube Composites. 2007.
(http://pubs.rsc.org.libproxy.aalto.fi/en/content/articlepdf/2007/sm/b704368f)
(3) Pidcock, G. C. & in het Panhuis, M. Extrusion Printing of Flexible Electrically Conducting Carbon Nanotube Networks. 2012.
(http://onlinelibrary.wiley.com.libproxy.aalto.fi/doi/10.1002/adfm.201200724/full)
(4) Image (http://www.ciaoimports.com/assets/images/willpowder/gellanlow.jpg)
Gellan Gum
• Anionic, polysaccharide biopolymer
• Hydrogel formation mechanism:
ionotrophic gel formation with cations
• Produced by Sphingomonas elodea
bacteria
• Used as a gelling, stablishing and
suspending agent
• In 3d printing used as a thickener
Commercial gellan gum
Proteins
(4) Inzana, Jason A.; Olvera, Diana; Fuller, Seth M.; Kelly, James P.; Graeve, Olivia A.; Schwarz, Edward M. et al. (2014): 3D printing of composite calcium
phosphate and collagen scaffolds for bone regeneration. In: Biomaterials 35 (13), S. 4026–4034. DOI: 10.1016/j.biomaterials.2014.01.064. (hyperlink4)
(5) Wu, Zhengjie; Su, Xin; Xu, Yuanyuan; Kong, Bin; Sun, Wei; Mi, Shengli (2016): Bioprinting three-dimensional cell-laden tissue constructs with
controllable degradation. In: Scientific Reports 6, S. 24474. DOI: 10.1038/srep24474. (hyperlink5)
(6) Wikipedia (Hg.) (2017): Collagentriplehelix - Collagen - Wikipedia. Online verfügbar unter https://en.wikipedia.org/w/index.php?oldid=759139140, zuletzt
aktualisiert am 16.01.2017, zuletzt geprüft am 20.01.2017.
(3) Chia, Helena N.; Wu, Benjamin M. (2015): Recent advances in 3D printing of biomaterials. In: Journal of
biological engineering 9, S. 4. DOI: 10.1186/s13036-015-0001-4. (hyperlink3)
(4) Inzana, Jason A.; Olvera, Diana; Fuller, Seth M.; Kelly, James P.; Graeve, Olivia A.; Schwarz, Edward M. et
al. (2014): 3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration. In:
Biomaterials 35 (13), S. 4026–4034. DOI: 10.1016/j.biomaterials.2014.01.064. (hyperlink4)
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3D-printing of gelatinmethacrylate:
• The material is a hydrogel of
polymers that are crosslinked
• The thermoresponsive behaviour
of the material allows for 3D-
printing
• Collapse of internal pores is a
challenge in processing, but can
be tackled by using stabilizing
co-polymers
(1) Li et. al. (2014) (https://www.hindawi.com/journals/ijps/2014/829145/abs/)
(2) Cruz et. al. (2010) (http://cdn.intechweb.org/pdfs/12148.pdf)
(3) Bose et. al. (2013) (http://www.sciencedirect.com/science/article/pii/S136970211300401X)
(4) Billiet et. al. (2014) (http://www.sciencedirect.com.libproxy.aalto.fi/science/article/pii/S0142961213011782)
(5) Schuurman et. al. (2013) (http://onlinelibrary.wiley.com.libproxy.aalto.fi/doi/10.1002/mabi.201200471/abstract)
Figure 2. The workflow related to the use of
3D-printing in tissue engineering [4]
39
• Gelatin methacrylate can be used in
tissue engineering
• The hydrogel is used as a cell 3D
scaffold, it is porous and these pores can
be cell laden for tissue growth
• The material is highly biocompatible and
can be precisely designed
• Cells can be grown without changes in
phenotype and the flow of water, oxygen
and nutrients is steady in the hydrogel
(1) Li et. al. (2014) (https://www.hindawi.com/journals/ijps/2014/829145/abs/)
(2) Cruz et. al. (2010) (http://cdn.intechweb.org/pdfs/12148.pdf)
(3) Bose et. al. (2013) (http://www.sciencedirect.com/science/article/pii/S136970211300401X)
(4) Billiet et. al. (2014) (http://www.sciencedirect.com.libproxy.aalto.fi/science/article/pii/S0142961213011782)
(5) Schuurman et. al. (2013) (http://onlinelibrary.wiley.com.libproxy.aalto.fi/doi/10.1002/mabi.201200471/abstract)
Figure 3. The material
architecture and pore
network [4]
Poly(3-hydroxybutyrate) PHB
41
[6] https://www.hindawi.com/journals/ijps/2014/829145/
[7] http://onlinelibrary.wiley.com/doi/10.1002/masy.201100237/full
[8] http://www.nature.com/articles/srep31140
[9] http://previews.123rf.com/images/molekuul/molekuul1204/molekuul120400071/13373407-Chemical-
composition-of-polyhydroxybutyrate-bioplastic-a-sustainable-alternative-to-oil-based-plasti-Stock-Photo.jpg
Poly(3-hydroxybutyrate) (PHB) :
• Natural polyester produced by microorganisms [6]
• Thermoplastic polymer - does not require additives such as
plasticizers [6]
• Biocompatible and biodegradable: Good for biomedical
applications [6]
• Non-toxic [6]
• Resistant to handling without presenting any visible damage
[7]
• Can be re-utilized to print additional structures without
affecting the reproducibility of the process [7]
• Drawbacks: hydrophobicity, surface chemical inactivity and
the lack of functional groups
• PHB can be used to produce scaffolds for tissue engineering
[6] (via Selective Laser Sintering from powder form) Chemical composition of poly(3-
hydroxybutyrate) [9]
Properties
• PHB presents mechanical properties
close to polypropylene and and other
biodegradable polyesters such as
polylactides.
• PHB is thermoplastic, which enables
fabrication. It becomes moldable
above a specific temperature and
solidifies upon cooling.
• Properties can be modified by
copolymerization.
• PHB is fabricated into a porous
structure, which effects its mechanical
properties that are important to the
fabricated object.
9.2.2019
42(1) 3D rinting of PHB porous structures Using Selective Laser Sintering (hyperlink)
(2) Synthesis, Structure and properties of PHAs: biological polyesters (hyperlink)
• Porous structure• Studies showed that the porous structure
of the printed model showed some
variation to the digital model.
• Challenge in processing is that
PHB might undergo thermal
degradation• Studies show that processing
does not have a major effect on the
thermal degradation
Chondroitin Sulphate(CS)
44
(5) Abbadessa, A., Blokzijl, M. M., Mouser, V. H. M., Marica, P., Malda, J., Hennink, W. E., & Vermonden, T. A thermo-responsive and photo-polymerizable chondroitin sulfate-
based hydrogel for 3D printing applications. Carbohydrate Polymers, 149, 163–174, 2016 http://doi.org/10.1016/j.carbpol.2016.04.080
(6) Silva, J. M., Georgi, N., Costa, R., Sher, P., Reis, R. L., van Blitterswijk, C. A., Mano, J. F. Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate
Multilayers for Cartilage Tissue Engineering. PLoS ONE, 8(2), 2013 http://doi.org/10.1371/journal.pone.0055451
Image from http://www.webmd.com/first-aid/cartilage
Chondroitin Sulphate (CS)
• The main glycosaminoglycan (GAG)
• component of cartilage.
• Responsible for providing compressive
loading
• resistance and maintenance of
cartilage.
• High negative charge density and
lipophilic nature
• lead to retention of water in extra-
cellular matrix.
• Fluctuation in water content provides
the compression resistance.
• Crucial components in the CNS,
capable of modulating nervous tissue.
• High load and stress resistance.
• Natural component of cartilage (removing
most toxicity issues.)
• Capable of high cell binding, partially due
to it’s high negative charge allowing it to
react with cell surface proteins.
• Control of factors such as porosity allows
modification of reaction.
• Natural presence in CNS allows for uses
in nervous tissue repair.
9.2.2019
45
Chondroitin Sulphate (CS)• Uses of products primarily in cartilage tissue engineering.
• Multi-layered support structures produced with chitosan.
• Cells readily attach, proliferate and remain metabolically active.
• In other studies, hydrogels of CS and large co-polymers have been
produced.
• These show good stress resistance, tunable porosity and cell binding
ability.
Photographs of CS involved hydrogel produced
3D structures with 2mm strand spacing
SEM Micrograph of chitosan and CS
structures on glass coverslips after 1 (top)
and 21 (bottom) days
(5) Abbadessa, A., Blokzijl, M. M., Mouser, V. H. M., Marica, P., Malda, J., Hennink, W. E., & Vermonden, T. A thermo-responsive and photo-polymerizable chondroitin sulfate-
based hydrogel for 3D printing applications. Carbohydrate Polymers, 149, 163–174, 2016 http://doi.org/10.1016/j.carbpol.2016.04.080
(6) Silva, J. M., Georgi, N., Costa, R., Sher, P., Reis, R. L., van Blitterswijk, C. A., Mano, J. F. Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate
Multilayers for Cartilage Tissue Engineering. PLoS ONE, 8(2), 2013 http://doi.org/10.1371/journal.pone.0055451
• Scaffolds can also be produced from CS and carbon nanotubes.
• Can produce a viable and neuron-rich network for use in nervous
tissue lesions.
• Possible uses in nerve regeneration, particularly when used soon after
injury.