Reversible inhibition of the oxidase-like activity of Fe single-atom nanozymes for drug detection

Mechanism research of nanozymes has always been of great interest since their emergence as outstanding mimics of friable natural enzymes. An important but rarely mentioned issue in mechanism research of nanozymology is the inhibitory effect of nanozymes. And conventional nanozymes with various active sites hinder the mechanism research, while single-atom Fe–N–C nanozymes with similar active sites to natural enzymes exhibit structural advantages. Herein, we synthesized Fe single-atom nanozymes (Fe-SANs) with ultrahigh oxidase-like activity and found that a common analgesic-antipyretic drug 4-acetamidophenol (AMP) had inhibitory effects for the oxidase-like activity of Fe-SANs. We investigated the inhibitory effects in detail and demonstrated that the inhibition type was reversible mixed-inhibition with inhibition constants (K(i) and [Image: see text]) of 0.431 mM and 0.279 mM, respectively. Furthermore, we put forward a colorimetric method for AMP detection based on nanozyme inhibition. The research on the inhibitory effects of small molecules on nanozymes expands the scope of analysis based on nanozymes and the inhibition mechanism study may offer some insight into investigating the interaction between nanozymes and inhibitors.