Preparation and characterization of tannic acid-ferric chloride-polyACG composite hydrogel microneedle patch

Skin is the largest organ of body, and chronic wounds can inevitably form when the skin injuries do not be healed promptly, and bacterial infection is a major challenge for healing chronic wounds. Hydrogel, a three-dimensional network structure, can help accelerate wound healing by absorbing exudate and maintaining moisture of wounds. However, the antibacterial property of hydrogel dressings still need be highly improved. In this study, a photothermal antibacterial hydrogel was prepared by using N-acryloyl-2-glycine (ACG), tannic acid (TA), FeCl₃, and hydroxyapatite (HAp). And subsequently exploiting a PDMS micro-needle mold to construct hydrogel microneedle patch which could penetrate the epidermis for deep-level antibacterial effects without causing strong pain. When TA∶ACG was fixed at 1∶20, the synthetic hydrogel exhibited high mechanical strength (790 kPa), long tensile strain (1043%), and good adhesion (25.04 kPa). Additionally, when FeCl₃∶TA was 1∶25, the hydrogel could reach 51°C under 808-nm laser irradiation for 2 minutes. As the proof of concept, this study demonstrates the hydrogel microneedle patch with photothermal effects can be utilized in clinical wound management, showing great potential for promoting wound healing, drug delivery, and clinical detection.