Ultrasound‐Driven Electric Conversion Hydrogel Coating Enhances Macrophage Efferocytosis for Non‐Invasive Skin Expansion

Abstract Skin soft‐tissue expansion, a key technique for tissue regeneration, promotes tissue repair by applying sustained mechanical tension. However, prolonged tension leads to the accumulation of apoptotic cells and impaired macrophage efferocytosis, thereby disrupting immune homeostasis and inhibiting regeneration. In this study, an ultrasound‐driven electric‐conversion hydrogel system (SHG@GBT) is developed, integrating piezoelectric heterojunctions with a reorganized hydrogel network. This system modulates macrophage efferocytosis through ultrasound‐generated electrical signals, optimizing the immune microenvironment and promoting regeneration. Piezoelectric heterojunctions are created by coupling the interfaces of graphene oxide (GO) and barium titanate (BTO) at multiple scales and are embedded in a reorganized network formed by cross‐linking oxidized hyaluronic acid and hydrazide‐modified hyaluronic acid. The mechanical compatibility of the hydrogel and the ultrasound response of the heterojunctions enhanced energy conversion efficiency, with the GO/BTO heterojunction improving BTO polarization and the GO network optimizing charge transfer. Under ultrasound stimulation, the local electric field generated by BTO activated macrophage calcium ion channels, increasing calcium influx and enhancing efferocytosis, angiogenesis, and collagen synthesis. In vivo studies have shown reduced accumulation of apoptotic cells and improved blood perfusion. This study introduces a noninvasive immune modulation strategy to optimize the efficacy and safety of skin soft tissue expansion.