High-Entropy Alloy/Zinc Sulfide Heterojunction-Based Hydrogel for Eliminating Bacteria and Stimulating Osteoblast Response

Integration of a high-entropy alloy (HEA) with nanozyme activity and a piezoelectric material with piezoelectricity is a promising strategy to develop a novel biofunctional material for the repair of infectious bone defects. Herein, a heterojunction of HEA (FeMnMoRuIr) and zinc sulfide (ZnS) (HEA@ZnS) is synthesized that exhibits enhanced piezoelectricity and nanozyme activities. Moreover, a piezoelectric hydrogel containing zein, sodium alginate, and HEA@ZnS (ZeAHZ) with antibacterial properties and pro-osteogenic capability is fabricated. Under acidic conditions, triggered by ultrasound, the piezoelectric effect of ZeAHZ enhances peroxidase-like activity and sonodynamic efficiency that produces a large amount of reactive oxygen species (ROS, ·O₂^- and ·OH) for collaboratively eliminating bacteria. Moreover, the superoxide-like activity and piezoelectric effect-enhanced catalase-like activity of ZeAHZ scavenge ROS (·O₂^- and H₂O₂) and produce oxygen due to the cascade reaction, which provides a favorable microenvironment for cell growth. Further, the piezoelectric effect of ZeAHZ generates electrical stimulation that significantly promotes osteoblast proliferation and differentiation. This study opens up a new path for designing a biomaterial with the capability of production/elimination of ROS and pro-osteogenesis by electrical stimulation, and ZeAHZ has great potential for accelerating bone regeneration.