Polyvinyl alcohol/tannic acid hydrogel prepared by a freeze-thawing process for wound dressing applications

The objective of this study was to develop an effective, potential wound dressing consisting of a blended hydrogel of polyvinyl alcohol (PVA) and tannic acid (TA). PVA is known for its biocompatibility and hydrophilicity, and TA is known for being a natural compound which can serve as a cross-linking agent and a therapeutic agent. To prepare the PVA/TA hydrogel, a blended aqueous solution of PVA and TA was processed through three cycles of freezing at -20 +/- 3 degrees C for 18 h followed by thawing at 25 degrees C for 6 h. Consequently, the PVA/TA hydrogel was successfully prepared through the freeze-thawing process. In an investigation of the hydrogel, it was found that the mechanical strength and hardness increased and that the moisture content decreased as the TA concentration was increased. Moreover, the PVA/TA hydrogel showed excellent antibacterial ability (>99.99%) and antioxidant ability (>92%).