Enhancing Stability of in Situ Crosslinked Hydrogel N,O-Carboxymethyl Chitosan – Aldehyde Hyaluronate by Supplementing Ionic Crosslinking of Alginate and Calcium Ions

Hydrogels based on Schiff’s base reaction of N,O-carboxymethyl chitosan (NOCC) and aldehyde hyaluronate (AHy) have been applied widely in several biomedical fields such as drug delivery, post-operative anti-adhesion, tissue regeneration, etc. However, their low mechanical strength and rapid degradation limit their use in longer-duration applications. This study aimed to investigate the effects of supplementing another biopolymer, alginate (Alg), to enhance the hydrogel crosslink network via ionic crosslinking with Ca2+ ions from calcium chloride (CaCl2). The hydrogel samples were characterised by their crossectional morphology, FTIR spectra, porosity, compression modulus, and swelling–degradation behaviours. Cytotoxicity and cell viability were also evaluated. The results revealed that this simple approach successfully improved the mechanical strength and stability of the hydrogel while conserving the in vitro biocompatibility. This suggested expanded potential biomedical applications of the hydrogels.