PVA/Poly(hexamethylene guanidine)/Gallic Acid Composite Hydrogel Films and Their Antibacterial Performance

Abstract

Carboxylated poly(vinyl alcohol) (PVA-COOH) is prepared by modifying PVA with succinic anhydride. Then, poly(hexamethylene guanidine (PHMG) as a cross-linker and gallic acid (GA) as an antioxidant are added to obtain PVA-based composite hydrogel films (PVA-COOH-PHMG/GA). The as-prepared PVA-based composite films show hydrophilic surfaces, high swelling ratios of 600–700%, low water solubility for PVA-COOH-PHMG samples (about 10%), and good mechanical properties. Importantly, when the initial bacterial concentration is 107 CFU/mL, the antibacterial rate of PVA-based composite films against Escherichia coli and Staphylococcus aureus can reach 99.999%. When the initial bacterial concentration is 108 CFU/mL, the antibacterial rates of these composite films against E. coli and S. aureus can be 99.9999% and 99.988%, respectively. The antibacterial mechanism is also discussed via a live/dead bacteria assay. The cytotoxicity test reveals that the resultant PVA-COOH-PHMG composite hydrogel films without GA have good biocompatibility toward L929 cells, but PVA-COOH-PHMG/GA composite films with addition of GA decrease the cell viability. Interestingly, the PVA-COOH-PHMG/GA composite hydrogel films can scavenge 70% of 1,1-diphenyl-2-picryhydrazyl (DPPH) free radical because of the release of GA, indicating an excellent antioxidant efficiency. It is anticipated that the resultant PVA-based composite hydrogel films with an adequate amount of GA not only possess excellent antibacterial properties but also exhibit a good antioxidant activity. Therefore, they show potential for biomedical field applications as wound dressings.