Innovative Materials

Thermoresponsive poly glycidylether coatings for cell sheet fabrication

Daniel Stöbener, Oliver Etzold, Anke Hoppensack, Melanie Uckert, Luis Cuellar and Marie Weinhart

Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, GER

Thermoresponsive polymers are commonly used in the field of tissue engineering and regenerative medicine, 12 especially in the fabrication of thermoswitchable surface coatings for cell sheet engineering.3 Above the lower critical solution temperature (LCST) of the coating, cells adhere to the surface and proliferate to confluence. Lowering of the temperature below the LCST triggers rehydration and swelling of the coating. This results in detachment of confluent cell sheets from the surface without use of enzymes, leaving the extracellular matrix (ECM) intact (Fig. 1).

Linear glycidylether based copolymers are thermoresponsive, biocompatible and have shown to be a new promising candidate for cell sheet engineering.45 We functionalized tissue culture substrates with photo-crosslinkable thermoresponsive glycidyl ether copolymers. The performance of the coatings in cell sheet fabrication was evaluated and compared to commercially available pNIPAm surfaces. Statistical thermoresponsive copolymers of glycidyl methyl ether (GME), ethyl glycidyl ether (EGE) and allyl glycidyl ether (AGE) were synthesized via monomer activated anionic ring opening polymerization using tetraoctylammonium bromide as initiator and triisobutylaluminium as activator.6 Thereby, good control over comonomer ratios, molecular weights, PDIs (1.2\leq \ 1.2) and hence the switching temperature of the polymers was achieved. Post-functionalization with benzophenone enabled photocrosslinking of the copolymers onto polystyrene culture dishes and silicon wafers with varying thickness by irradiating spin coated films with a 7.5 J/cm2 LED (365 nm). Characterization was performed by atomic force microscopy (AFM) and ellipsometry. We were able to tune and optimize the coating parameters and hence surface characteristics such as coating thickness and degree of crosslinking for fabrication of primary human fibroblast cell sheets. The BMBF (FKZ 13N13523)is kindly acknowledgedfor financial support.

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Fig. 1. Temperature triggered cell sheet fabrication with thermoswitchable cell culture dishes.