Self-Healing, Injectable Gelatin Hydrogels Cross-Linked by Dynamic Schiff Base Linkages Support Cell Adhesion and Sustained Release of Antibacterial Drugs

A new class of dynamic hydrogels made through Schiff base bonds based on gelatin (type A and B) and polyethylene glycol dibenzaldehyde (diBA-PEG, 2000 and 4000gmol(-1)) is developed. Hydrogels form in situ by mixing aqueous solutions of gelatin and diBA-PEG at a carefully adjusted pH. Compression test shows that the samples based on gelatin A are able to withstand at least ten cyclic loading/unloading without crack formation and significant permanent deformation. Self-healing behavior of the hydrogel is proved by rheological measurements and also visual method. This hydrogel is proven to be injectable and nontoxic. Performance of the hydrogel in loading and delivery of clindamycin hydrochloride, as an antibacterial model drug, is evaluated against Staphylococcus aureus via antibacterial activity test. In vitro release of clindamycin hydrochloride is studied through an innovative method and it becomes clear that the release of clindamycin hydrochloride from this hydrogel follows a zero-order kinetics.