Chitosan/polyvinyl alcohol/tannic acid multiple network composite hydrogel: preparation and characterization

The development of easy and cost-effective strategies for making multifunctional hydrogels is of great scientific interest. Here, a chitosan/polyvinyl alcohol/tannic acid (CS/PVA/TA) composite hydrogel was prepared by a simple method of γ-ray-induced crosslinking and immersion in TA solution. The chemical composition, transparency, microstructure, mechanical properties and antibacterial activity of the obtained composite hydrogel were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy, scanning electron microscopy (SEM), tensile measurement, and antibacterial test, respectively. The immersion in TA not only provided a CS (Mw 20,000 g.mol−1)/PVA composite hydrogel with improved mechanical performance, i.e., tensile strength and elongation-at-break increased by 1100 and 487%, respectively, but also it preserved high transparency of the pure irradiated PVA hydrogel (transmittance exceeded 50% at 660 nm). In addition, the composite hydrogel possessed good antibacterial activity against gram-negative and gram-positive bacteria. The rationality of the immersion TA method in principle was proved by the hydrogen bond simulation. This work provides a simple method for the preparation of multifunctional hydrogels, suitable for large-scale production, and is expected to promote their application in the fields of biomedicine and wound dressings.