Preparation and characterization of carboxymethyl chitosan/polyvinyl alcohol composite hydrogel with improved mechanical and antibacterial properties

Biopolymer-based antibacterial hydrogels have attracted considerable interest in biomedical field. Herein, we report on an effective strategy for the preparation of carboxymethyl chitosan/polyvinyl alcohol (CMCh/PVA) composite hydrogel with improved mechanical and antibacterial properties by using poly(ethylene glycol) diglycidyl ether (PEGDE) as crosslinking agent and zinc acetate (ZnAc2) as catalyst, respectively. FT-IR and gelation time measurements confirm that the introduction of both PVA and ZnAc2 can accelerate the formation of ester bonds between CMCh and PEGDE. SEM images reveal the interconnected macroporous inner architecture in the current CMCh/PVA composite. While the hydrogels exhibit pH-sensitive swelling behaviors in the pH range from 3 to 11, they remain relatively stable in phosphate buffered saline buffer. Compression mechanical tests show that, when increasing the PVA concentration to 1.0%, the resultant CMCh/PVA composite hydrogel shows a compressive strength of 1.96 MPa. The dried composite sample prepared with 1.0% PVA has a water absorption capacity of 1860%. The antibacterial activities of the CMCh/PVA hydrogel are studied against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus by inhibition zone method, indicating that the composite hydrogel exhibits improved antibacterial activity after the adsorption of zinc ions.