A highly transparent dopamine-copolymerized hydrogel with enhanced ROS-scavenging and tissue-adhesive properties for chronic diabetic wounds.

Chronic diabetic wounds with complex symptoms represent a major challenge in clinical practice, causing a serious threat to human health and life. Excessive oxidative stress and persistent inflammatory responses are the important reasons for the long-term difficult healing of diabetic wounds. Designing wound dressing materials with intrinsic antioxidant performance, high transparency, adhesiveness, and favorable mechanical properties is of great significance for promoting wound healing, especially in movable parts. Here, a dopamine-copolymerized highly transparent antioxidant hydrogel was developed for the treatment of chronic diabetic wounds. The hydrogel was easily prepared via free radical polymerization using acrylated dopamine monomer (ADA), acrylamide (AM), and phenylboronic acid modified dextran (DP). The dynamic phenylborate ester bonds formed between the catechol of polydopamine and phenylboronic acid effectively mitigated the darkening of the hydrogel color caused by the auto-oxidation of catechol, resulting in the PAM/PDA/DP hydrogel (DP3) with durable transparency. In addition, this hydrogel had good adhesiveness and mechanical properties, as well as desirable reactive oxygen species (ROS)-scavenging performance. Furthermore, in vivo results demonstrated that DP3 hydrogel can stimulate the polarization of macrophages toward anti-inflammatory M2 phenotype, increase the secretion of anti-inflammatory factors, so as to smooth the transition of wound healing from the inflammatory phase to the proliferative phase, and accelerate the repair of diabetic wounds by promoting angiogenesis and collagen deposition. Therefore, the DP3 hydrogel holds great potential for remolding the tissue regeneration microenvironment and serving as a promising dressing for chronic diabetic wounds. STATEMENT OF SIGNIFICANCE: Polydopamine (PDA)-based hydrogels have been widely explored. However, existing PDA-based hydrogels suffer from low content of catechol groups and inferior transparency, and are prone to oxidation darkening during storage. In this study, a dopamine-copolymerized hydrogel with high catechol content was developed. The catechol groups are partially protected by phenylboronic acid-modified dextran, resulting in durable transparency and good adhesiveness of the hydrogel. The hydrogel exhibits desirable antioxidant performance and can effectively promote chronic diabetic wound healing by relieving oxidative stress and regulating immune function. This highly transparent hydrogel with intrinsic antioxidation and self-adhesiveness properties represents a potential and effective strategy for chronic wound management.