Recent Advancements and Future Prospects of Asymmetrically Coordinated Single-Atom Nanozymes with High Enzymatic-like Activity for Biotherapy and Diagnosis: A Review

Single-atom nanozymes (SAzymes) are widely regarded as promising next-generation artificial nanozymes due to their nearly 100% atom usage, distinctive electronic structures, and high catalytic efficiency. Regulating the coordination configurations of the active site plays a significant role in tailoring short-range electronic interactions, which can overcome the inherent chemical inertness of metal-N4 active sites. Excitingly, asymmetrically coordinated SAzymes (AC-SAzymes) show a deformed electron cloud distribution, leading to superior catalytic activities compared to the traditional metal-N4 active sites. In this Review, we systematically summarize the recent advancements in the AC-SAzymes acting as enzymatic reaction catalysts, including the types and mechanisms of enzyme-like reactions, the preparations and characterizations of AC-SAzymes, and the applications of AC-SAzymes. Particularly noteworthy is the discussion of the enzymatic reaction mechanism and the bioapplication of AC-SAzymes. Finally, a perspective on future developments of AC-SAzymes in the applications of enzymatic reactions is provided.