Tai-Chi hydrogel with Chinese philosophy and photothermal properties for accelerated diabetic wound healing

Bacterial cellulose (BC) and photothermal hydrogels are widely used currently in wound repair. However, modified and functionalized BC may damage the advantages of natural BC which limits its application as a wound dressing, and photothermal hydrogels have a problem of secondary damage by overheating during the photothermal therapy process. Therefore, a Tai-Chi hydrogel inspired by the Chinese philosophy of "Tai Chi" was developed, which consists of BC, namely, Yin, and polyvinyl alcohol/polydopamine (PVA/PDA), namely, Yang. Two hydrogels of Tai-Chi hydrogel have opposite properties to selectively cover healthy skin and the wound and to adjust/balance the wound temperature under NIR irradiation. In vitro experiments demonstrate that mild warm caused by Yang hydrogel under NIR irradiation promotes polarization of RAW 264.7 macrophages to M2 phenotype. Tai-Chi hydrogel itself has a significant therapeutic effect on a diabetic wound by regulating the inflammatory microenvironment. In addition, Tai-Chi hydrogel in combination with NIR irradiation exhibited a remarkably therapeutic effect by promoting re-epithelialization and angiogenesis, accelerating collagen deposition and macrophage polarization to M2 phenotype. This work first presents a novel strategy for designing functional materials with opposite properties inspired by the philosophy of "Yin-Yang" in "Tai Chi" as a diabetic wound dressing. TOC Tai-Chi hydrogel was first developed in this study inspired by the Chinese philosophy of "Tai Chi," which consists of Yin and Yang hydrogel with opposite properties. Tai-Chi hydrogel itself has a significant therapeutic effect on a diabetic wound by regulating the inflammatory microenvironment. Furthermore, in combination with NIR irradiation, the Tai-Chi hydrogel exhibited a remarkably therapeutic effect by promoting re-epithelialization and angiogenesis, accelerating collagen deposition and macrophage polarization to M2 phenotype, especially at the early stage of the healing process (day 3).