CeN4-SAzyme: A Novel Single-Atom Nanozyme for H2O2 Sensing and Organophosphorus Detection

In this study, we have developed an optimized single-atom nanozyme, referred to as CeN4-SAzyme, by employing a bottom-up approach and engineering Ce-N-C nanostructures. Through extensive characterization, we have identified the atomic structures of CeN4-SAzyme, in which Ce atoms are securely anchored on a porous N-doped carbon support, forming symmetrically coordinated CeN4 moieties. Our theoretical and experimental analyses have consistently confirmed that these atomic CeN4 moieties exhibit remarkable peroxidase-like activity, specifically catalyzing the oxidation of colorless 3,3',5,5'-tetramethylbenzidine dihydrochloride (TMB) by H2O2 under acidic conditions, resulting in the production of a blue color.

The distinctive peroxidase-like activity of CeN4-SAzyme makes it an excellent candidate for H2O2 sensing applications, as well as a versatile colorimetric reporter for (per)oxidase activities and the detection of their substrates. To further demonstrate its practical utility, we have successfully constructed a sequential catalytic platform incorporating CeN4-SAzyme, AChE, and choline oxidase (ChOx) for sensitive and visual detection of organophosphorus compounds (OPs) in real samples, without encountering significant interference.

Overall, our findings highlight the potential of CeN4-SAzyme as a highly efficient nanozyme with specific applications in H2O2 sensing and OP detection, offering promising prospects for various analytical and biomedical applications.