In situ forming chitosan hydrogels with tunable physicomechanical and tissue adhesive properties

In situ forming hydrogels generated upon spontaneous and biocompatible reaction between two polymeric components in physiological conditions are widely investigated as injectable and implantable materials for biomedical applications. However, since their mechanical properties depend on the crosslinking density which also controls the gelation rate, it is still an important challenge to control a wide range of mechanics while maintaining the gelation kinetics. In this study, in situ forming chitosan hydrogels via Schiff base formation were developed. Their mechanical properties were controlled by introducing tunable polymer graft architecutre. Poly(ethylene glycol) (PEG) with varying lengths and densities were conjugated to the chitoran backbone, resulting PEGylated chitosan not only dissolved in neutral aqueous solutions but also allowed to contol the mechanical properties of the hydrogel while maintaining facile gelation kinetics. The chain length of the crosslinker, PEG-dialdehyde, was also adjusted to further control these properties by the interaction with polymer grafts. In addition, the tissue adhesive properties of chitosan hydrogels were evaluated by ex vivo and in vivo models, demonstrating their clinical potential