A Pt₁Pd Single‐Atom Alloy Nanozyme with Boosted Enzyme‐Like Activity for Efficient Photo‐Mediated Tumor Therapy

Single‐atom nanozymes (SAzymes) are emerging natural enzyme mimics and have attracted much attention in the biomedical field. SAzymes with Metal─N x sites designed on carbon matrixes are currently the mainstream in research. It is of great significance to further expand the types of SAzymes to enrich the nanozyme library. Single‐atom alloys (SAAs) are a material in which single‐atom metal sites are dispersed onto another active metal matrix, and currently, there is limited research on their enzyme‐like catalytic performance. In this work, a biodegradable Pt 1 Pd SAA is fabricated via a simple galvanic replacement strategy, and for the first time reveals its intrinsic enzyme‐like catalytic performance including catalase‐, oxidase‐, and peroxidase‐like activities, as well as its photodynamic effect. Experimental characterizations demonstrate that the introduction of single‐atom Pt sites contributes to enhancing the affinity of Pt 1 Pd single‐atom alloy nanozyme (SAAzyme) toward substrates, thus exhibiting boosted catalytic efficiency. In vitro and in vivo experiments demonstrate that Pt 1 Pd SAAzyme exhibits a photo‐controlled therapeutic effect, with a tumor inhibition rate of up to 100%. This work provides vital guidance for opening the research direction of SAAs in enzyme‐like catalysis.