Self-healing and injectable polysaccharide hydrogels with tunable mechanical properties

An injectable polysaccharide hydrogel based on cellulose acetoacetate (CAA), hydroxypropyl chitosan (HPCS), and amino-modified cellulose nanocrystals (CNC-NH2) was prepared under physiological conditions. CNC-NH2 acted as both physical and chemical cross-linker. The effects of CNC-NH2 loading on the mechanical properties, internal morphology and gelation time were investigated; the maximum storage modulus was observed for a gel containing 0.80 wt% of CNC-NH2. The structure and properties of the polysaccharide hydrogel were characterized by Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, Raman spectroscopy and rheology testing. The polysaccharide hydrogel exhibited pH- responsive properties and excellent stability under physiological conditions. The hydrogel also exhibited self-healing behavior under acidic conditions via enamine bond exchange. In addition, CCK-8 cytotoxicity study with fibroblast L929 cells demonstrates good biocompatibility of CNCs reinforced hydrogels.