In-situ forming thermosensitive hydroxypropyl chitin-based hydrogel crosslinked by Diels-Alder reaction for three dimensional cell culture.

Injectable thermosensitive hydrogels crosslinked physically have been extensively studied as scaffolds in biomedical field, however, their low gel stability with weak strength limits their potential applications. Here, a novel thermosensitive furyl-modified hydroxypropyl chitin polymer was synthesized homogeneously in aqueous solution for developing injectable and dually crosslinked degradable hydrogel by integration of Diels-Alder click reaction using crosslinker maleimide-terminated PEG under physiological conditions. The dually crosslinked chitin-modified hydrogel showed much higher mechanical strength and slower biodegradation rate in contrast with the solely physically crosslinked thermosensitive hydroxypropyl chitin hydrogel. Cells encapsulated in the hydrogel displayed sustainable proliferation and good ability of self-assembling to form multicellular spheroids. In vivo investigation of the thermosensitive chitin-based dually crosslinked hydrogel showed favorable injectability, in-situ thermogelation and good biocompatibility. Thus the injectable, biodegradable and biocompatible dually crosslinked chitin-based hydrogel holds great potential for being applied in three dimensional cell culture and tissue repair.