Multifunctional modified chitosan hydrogel with excellent comprehensive properties by one pot

Traditional multifunctional hydrogels introduce multiple functional groups through multi-step reactions, and the processes are complex. In this paper, the multifunctional hydrogel was prepared by one pot method, and the preparation was facile and aqueous-based. Chitosan-dihydroxybenzaldehyde (CS-DHB) multifunctional hydrogel was prepared with chitosan (CS) and 3,4-dihydroxybenzaldehyde (DHB) as raw materials, and aluminum chloride hexahydrate (AlCl₃·6H₂O) as a crosslinking agent. The internal structure of the hydrogel was observed by scanning electron microscopy (SEM), and the interconnected pores provided the basis for the swelling property. The method of Schiff base reaction coupling with catechol was simple and convenient, resulting in an adhesion strength of up to 80.2 kPa. The hydrogel could be gelled quickly in situ (within 60 s). It exhibited solid-like behavior (G' > G") over a frequency range of 0.1-50 Hz, indicating a stable network structure. The degradation ratio exceeded 80% after 17 days. The hydrogel could eliminate stable free radicals (2,2-diphenyl-1-picrylhydrazyl, DPPH), and its antibacterial ratio was 90% and 98% against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) respectively, showing excellent antioxidant and antibacterial properties. In addition, the hydrogel had good cytocompatibility and hemocompatibility.