An injectable and self-healing hydrogel for spatiotemporal protein release via fragmentation after passing through needles.

A dynamic hydrogel formulated by mixing a glycol chitosan (GC) and an oxidized dextran (Odex) were studied for protein-controlled release in conjunction with the hydrogel fragmentation. A series of injectable dynamic hydrogels were derived from GC and Odex upon simple mixing without the addition of chemical crosslinking agents. The gelation readily took place at physiological pH and temperature. The influence of the concentration of GC and Odex on the gelation time, mechanical properties, water content, in vitro degradation were investigated. The Odex/GC hydrogels showed good self-healing ability under physiological conditions and kept the dynamic Schiff-base linkage at over 2 wt %. The release kinetics of a model protein (bovine serum albumin) was found to be controlled by changing the needle size upon injection, attributed to modulation of apparent size and shape of the fragmented hydrogels even in the self-healed state. Therefore, the GC-based injectable and dynamic hydrogels are expected to be a promising platform for protein delivery system and various biomedical applications.