Electric-Eel-Inspired Ionic Power Source Microneedles With Self-Reporting Structural Colors for Wound Healing

Microneedles have come to the forefront in the field of disease treatment. Efforts in this area are focused on developing specific microneedle systems with distinctive functions to promote their values. Here, inspired by the features of electric-eel and chameleon, we conceive a kind of ionic power source microneedles (IPSMs) with self-reporting structural colors for wound healing. The IPSMs consist of three layers, including a high KCl bottom layer, a cation-selective middle layer, and low KCl ionic-responsive tips with structure color. These IPSMs present an inherent electric field due to the internal unidirectional movement of K+, which can produce electrical stimulation for promoting wound healing. Besides, the constant movement of K+ from the bottom to the tips will lead to volume increase of the tips due to the chelation-derived bond energy change. This can result in the variation of the structure colors, acting as a visual signal for monitoring the electrical performance and providing a valuable reference for timely dressing changes. Furthermore, silver nanoparticles are integrated to impart them with antibacterial capacity and improved electrical performance. We demonstrated that this IPSM can promote wound healing, taking advantage of its electrical performance, antibacterial capacity, and self-reporting capacity, exhibiting great potential for practical wound healing.