Sodium alginate-based recyclable supramolecular hydrogel with anthocyanin for pH-sensing colorimetric and...

Wound status monitoring has emerged as a promising strategy to enable timely intervention for effective wound infection management and promote wound healing. Herein, a recyclable alginate hydrogel film with pH-sensing and antibacterial functions was developed as a smart wound dressing. The hydrogel film (SA-Anth) was fabricated via a two-step process, i.e., an evaporation-induced self-assembly of sodium alginate solution doped with anthocyanin and glycerin, followed by Ca²⁺-mediated ionic cross-linking using CaCl₂. Taking advantage of the pH-responsiveness of anthocyanin, the hydrogel film exhibited distinct color changes from red-purple at pH 5.0 to violet-blue at pH 7.3 and further to green at pH 9.0, suggesting its potential for visual monitoring of wound pH variations associated with infection. The incorporation of anthocyanin endowed the film with antibacterial activity, achieving bacterial reduction rates of 90.48% against E. coli and 98.10% against S. aureus. The hydrogel film also exhibited wound-dressing-relevant properties, including appropriate physicochemical performance, a low hemolysis ratio, and good in vitro cytocompatibility. In an S. aureus-infected rat full-thickness wound model, SA-Anth treatment enhanced wound closure and improved histological features of tissue repair compared with the control treatments. Furthermore, the de-crosslinking of the ionically crosslinked network was triggered by the addition of EDTA, enabling the recovery of the alginate component. The SA-Anth hydrogel film integrates pH-responsive visual indication, antibacterial activity, favorable biocompatibility, infected-wound repair performance, and EDTA-assisted material recovery, providing a promising platform for intelligent wound-dressing applications.