A rhein-integrated hydrogel dressing with antibacterial, antioxidant and pH-responsive colorimetric properties

Integrating bioactive function with wound-status indication remains a major challenge in the design of hydrogel dressings for complex wound management. Most pH-responsive hydrogels still rely on separate bioactive and sensing components, leading to increased compositional and fabrication complexity and highlighting the need for unified platforms based on a single bioactive molecule with intrinsic pH responsiveness. In this work, a multifunctional SF/HA/Rhe hydrogel dressing was developed by incorporating rhein (Rhe), a plant-derived small molecule, into a silk fibroin/hyaluronic acid (SF/HA) matrix. Rhe served as a single functional component that simultaneously endowed the hydrogel with antibacterial, antioxidant and pH-responsive colorimetric properties. The optimized SF/HA/Rhe hydrogel achieved antibacterial rates above 94% against Staphylococcus aureus, Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). It also exhibited strong antioxidant activity, with an ABTS radical scavenging rate of 87.22% and effective reduction of intracellular ROS accumulation. In addition, the hydrogel showed a distinct pH-dependent colorimetric response over the wound-relevant pH range of 5.5-7.5, allowing visual indication of local pH variations. The SF/HA/Rhe hydrogel further displayed favorable mechanical performance and biocompatibility, with cell viability above 90% and hemolysis below 5%. Overall, these findings provide a feasible strategy for multifunctional hydrogel dressings with integrated antibacterial, antioxidant and visual pH monitoring.