Single-atom iron nanozyme with oxidase-like activity for ultrasensitive polyphenol detection

Colorimetric sensors based on nanozymes hold significant potential in the fields of analysis and sensing. However, most nanozymes have poor selectivity and relatively low catalytic activity, limiting their practical applicability. Herein, an Fe-N-C single-atom nanozyme (Fe-SAzyme) with excellent catalytic activity was synthesized through a ZIF-templating and pyrolytic strategy. The as-synthesized Fe-SAzyme mimics oxidase activity by catalyzing the oxidation of 3,3',5,5'-tetramethylbenzidine to generate distinctive color reactions. Additionally, Fe-SAzyme was successfully utilized in the colorimetric detection and discrimination of various polyphenols based on nanozyme inhibition. Furthermore, a colorimetric sensor with a detection limit of 0.04 μg mL^-1 was developed for the quantitative detection of pyrogallol. This work provides a new sensing technique for detecting polyphenolic compounds using single-atom iron nanozymes, demonstrating their promising potential in the fields of food safety and environmental protection.