Enhancing Peroxidase‐Like Activity and Photothermal Property of Copper Single‐Atom Nanozyme via A Cascade Competition Strategy.

Single‐atom nanozymes (SANs) are promising enzyme‐active catalysts due to their maximum atomic utilization. However, it is still a challenge to precisely regulate the single‐atom structure, especially in multimetallic MOFs. Based on the Cu‐N4 structure of Zn4Cu1, a cascade competition strategy mediated by a buffer (polydopamine) is proposed for the first time, which induces a one‐step nonthermal reaction to precisely remove the inactive Zn site and adjust the Cu coordination environment. Experimental results and theoretical calculations show that the Cu single‐atom nanozyme with Cu‐N2O2 structure (Cu‐N/O) breaks the strong steric restriction, and the exposed Cu active site can better adsorb H2O2, making it have peroxidase‐like activity. Compared with traditional bimetallic (Cu4Zn1) and monometallic (Cu‐MoF) nanozymes, it has stronger peroxidase‐like catalytic activity and photothermal properties, as well as good photocatalytic activity and extremely strong stability. It is successfully applied to Lateral flow immunoassay to achieve three‐mode ultrasensitive detection of Escherichia coli O157:H7, and the test strips after detection are subjected to broad‐spectrum sterilization treatment. [ABSTRACT FROM AUTHOR]