Rhein functionalized cationic guar gum- bovine serum albumin hydrogel dressing with pH-responsive delivery for wound healing and pH monitoring.

Dynamic changes in wound pH provide valuable information for assessing the wound microenvironment and guiding timely therapeutic intervention. However, conventional pH-responsive hydrogel dressings often require the separate incorporation of therapeutic agents and sensing moieties, resulting in increased compositional complexity and less efficient fabrication. In this study, a diagnostic-therapeutic integrated Rhe@CG-BSA hydrogel dressing was developed by utilizing the pH-dependent zeta potential variation of bovine serum albumin (BSA) and the pH-indicating function of rhein (Rhe). The CG-BSA matrix provides the structural framework, while rhein acts as the single multifunctional component that integrates visual pH sensing, antibacterial, and antioxidant properties. The Rhe@CG-BSA hydrogel showed favorable wet-tissue adhesion, enabling intimate contact with irregular wound surfaces. In vitro assays demonstrated that the hydrogel provided intuitive colorimetric indication over the pH range of 5.0-7.4 and exhibited pH-regulated Rhe release, with accelerated release under acidic conditions. Moreover, the hydrogel demonstrated antibacterial and antioxidant activities in vitro. In a full-thickness S. aureus-infected wound model, Rhe@CG-BSA enabled visual tracking of wound pH changes, reduced residual bacterial colonization and accelerated wound closure, leaving only 0.96% residual wound area on day 14. This study presents a novel strategy for developing diagnostic-therapeutic integrated hydrogel dressings based on a single multifunctional component.