Multifunctional polyvinyl alcohol/gallic acid functionalized chitosan hydrogels prepared by freeze-thaw method for potential application as wound dressings.

The design of multifunctional hydrogel dressings to effectively promote wound healing is highly desirable in clinical trauma and surgery. Inspired by excellent mechanical properties of polyvinyl alcohol (PVA) and strong adhesion of polyphenols, gallic acid was grafted onto chitosan molecular chain (CS-GA) by free radical polymerization in this study, and PVA/CS-GA hydrogels were successfully prepared by repeated freeze-thaw method, without introducing toxic crosslinking agents. The prepared PVA/CS-GA hydrogels could adhere to various substrates, which confirmed excellent universal adhesion properties. The red blood cells adhesion ratio was 67.1%, indicating its potential for promoting wound coagulation. Meanwhile, the mechanical strength of PVA/CS-GA hydrogel was significantly enhanced, exhibiting approximately twice tensile strength and failure stretch compared with PVA hydrogel. Furthermore, attributing to GA molecule, PVA/CS-GA hydrogels not only showed favorable antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), but also could scavenge free radicals, showing effective antioxidant activity. The hydrogels also had good biocompatibility, met the basic requirements of biomedical materials and may promote wound repair. It should be noted that the content of GA had significant impact on cytotoxicity. Therefore, multifunctional PVA/CS-GA hydrogels with excellent mechanical, adhesion, antioxidant, antibacterial and biocompatible properties show promising potential applications in the biomedicine field, especially as functional wound dressings. Inspired by excellent mechanical properties of PVA and strong adhesion of polyphenols, PVA/CS-GA hydrogels with antibacterial, antioxidant, hemostatic, good biocompatibility, suitable adhesion and strong mechanical properties were successfully prepared by freeze-thaw method, which have great potential and application prospect as functional wound dressings. [Display omitted] • Multifunctional composite hydrogels are designed by non-toxic freeze-thaw method. • Polyphenol endows hydrogels with universal adhesion, and polyvinyl alcohol endows hydrogels with good elasticity. • The hydrogels exhibit excellent antioxidant, antibacterial and biocompatible properties. • The hydrogels can meet the requirements of ideal wound dressings. [ABSTRACT FROM AUTHOR]