Photosynthetic alginate dressing enables sustained oxygen delivery through chloroplast-powered Hill reaction to promote angiogenesis and macrophage reprogramming for chronic wound healing

Chronic wounds are very difficult to heal due to persistent hypoxia, impaired angiogenesis and dysregulated inflammation. To address these problems, we developed a photosynthetic hydrogel dressing (SFCc) by integrating chloroplasts into an alginate-based matrix and optimizing the Hill reaction. Our system implements a dual photoprotection strategy using ferricyanide as an electron acceptor coupled with catalase (Cat), effectively neutralizing reactive oxygen species while sustaining the production of photosynthetic oxygen. The SFCc hydrogel demonstrated controlled release of oxygen and maintained >90% chloroplast viability for 72 h. In a pressure ulcer model, the hydrogel significantly decreased the expression of hypoxia-inducible factor-1α, enhanced angiogenesis with a 5.8-fold increase in the vascular density of CD31 and promoted the polarization of macrophages toward the regenerative M2 phenotype; these changes collectively accelerated wound healing. This chloroplast-powered platform represents a breakthrough in biomimetic oxygen delivery. Its unique function involves synchronizing oxygen supply with metabolic demand through light modulation while facilitating microenvironment-responsive release via pH-sensitive and Cat-sensitive mechanisms. Our photosynthetic approach overcomes the limitations of conventional oxygen carriers and offers a transformative strategy for chronic wound management and ischemic tissue repair.