Bioactive yet antimicrobial structurally stable collagen/chitosan/lysine functionalized hyaluronic acid – based injectable hydrogels for potential bone tissue engineering applications

Novel, biocompatible, multifunctional, injectable genipin crosslinked collagen/chitosan/lysine-modified hyaluronic acid based hydrogels (ColChHAmod) were prepared in a facile, one-step procedure. The novelty of the current approach lies in the functionalization of hyaluronic acid (HA) with primary amine groups by lysine attachment, and its further use as a component of the injectable sol. The obtained derivative, HAmod, could form, upon crosslinking with genipin, covalent bonds with other components of the hydrogel network, resulting in structurally stable, better-defined hydrogels. We have demonstrated that, by adjusting HAmod content and genipin concentration, hydrogels with tunable physicochemical characteristics (swelling, wettability, tendency for enzymatic degradation) and properties adequate for the potential bone tissue regeneration can be prepared. Storage modulus measurements indicated that HAmod has positive effect on mechanical characteristics of hydrogels prepared. It was also revealed that the ColChHAmod-based hydrogels are characterized by a high porosity (85–95%). The in situ rheological measurements confirmed the injectability of the obtained hydrogels. The in vitro cell culture studies showed that the surface of all materials prepared was biocompatible, as they supported proliferation and adhesion of osteoblast-like cells followed by ALP expression. The intrinsic antibacterial activity of the hydrogels against Escherichia coli was also demonstrated in in vitro experiment.