Tetronic-grafted chitosan hydrogel as an injectable and biocompatible scaffold for biomedical applications

In recent years, injectable chitosan-based hydrogels have been widely studied towards biomedical applications because of their potential performance in drug/cell delivery and tissue regeneration. In this study, we introduce a simple and organic solvent-free method to prepare tyramine-tetronic-grafted chitosan (TTeC) via activation of four terminal hydroxyl groups of tetronic, partial tyramine conjugate into the activated product and grafting the remaining activated moiety of tetronic-tyramine onto chitosan. The grafted copolymer was well characterized by UV-Visible, (1)H NMR, and Thermogravimetric analysis. The aqueous TTeC copolymer solution rapidly formed hydrogel in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) at physiological conditions. The gelation time of the hydrogel was performed within a time period of 4-60 s, when the concentrations of HRP, H2O2, and polymers varied. The hydrogel exhibited highly porous structure which could be controlled by using H2O2. In vitro cytotoxicity study with Human Foreskin Fibroblast cell using live/dead assay indicated that the hydrogel had high cytocompatibility and could play a role as a scaffold for cell adhesion. The injectable hydrogels did not cause any inflammation after two weeks and one day of the in vivo injection. The obtained results demonstrated a great potential of the TTeC hydrogel in biomedical applications.