Special Poster Session Biofabrication
Bioprinting of larger tissues and eventually organs presents a tremendous opportunity to challenge the status quo for medical treatments of all kinds of illnesses. Necessary for the successful implementation of bioprinting is improving the cell survival during the printing process, where cells are subjected to significant shear forces. A possible way to improve cell viability and to expand the bioprinting window is the encapsulation of cells in hydrogels, which can be done using microfluidics.
Poly(2-oxazolines) possess unique properties making them an ideal synthetic polymer for the stable encapsulation of cells. They are biocompatible, while providing excellent opportunities for a functionalization at the side chain and both termini of the polymer. Several different modifications, for example free thiol groups at the side chain, are available which allow covalent crosslinking via thiol-ene reaction or Michael addition. To obtain POx-based hydrogel precursors 2-ethyl-2-oxazoline was randomly copolymerized with 2-(3-butenyl)-2-oxazoline, which were then functionalized with free thiol groups for hydrogel formation via thiol-ene reaction. Combining these two polymers with double three-dimensional flow focusing microfluidic chips allows the production of droplets of varying sizes with high uniformity. The first 3D channel intersection can be used for flow focusing and/or mixing of A/B components, while the second 3D intersection is used for stable droplet production. A 3D contoured narrowing allows for precise control of achieved droplet sizes. After production, the droplets can be crosslinked on demand either using UV irradiation or visible light, depending on the chosen radical initiator. This allows to tailor the system towards specific needs of cells as well as further production parameters. The final droplets can then be used either as bioink alone or as additive in conventional bioinks to ensure cellular protection.
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This research has received funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – project number 326998133 – TRR 225 (subproject A06).