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

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