Dual-site Se/NC specific peroxidase-like nanozyme for highly sensitive methimazole detection

Abstract

Tuning the nanozyme′s activity and specificity is very crucial for developing highly sensitive sensors for various applications. Herein, selenium-doped porous N-doped carbon skeletons (Se/NC) nanozymes with highly specific peroxidase-like activity were synthesized by a MOF-pyrolysis-doping protocol. Se doping adjusted the electronic structure of NC by introducing more vacancies, defective carbon and graphitic N, and endowed the resultant Se/NC enhanced charge transfer and substrate affinity. The Se/NC exhibited specific peroxidase-mimicking activity and could catalyze 3,3′,5,5′-tetramethylbenzidine oxidation by H₂O₂. Density functional theory (DFT) calculations and experimental trials indicated that both SeO and C–Se–C species were the main active sites of Se/NC. The C–Se–C bond is the main catalytic active site endowing Se/NC with the property of nanozyme, while the SeO bond effectively enhances its affinity to H₂O₂ and accelerate H₂O₂ dissociation. The Se/NC showed an approximately 185-fold increase in peroxidase-like activity compared to NC. Based on the inhibition of the peroxidase-like activity of Se/NC by methimazole, a colorimetric sensor was developed to achieve its sensitive detection with 2 nmol/L of limit of detection. It was successfully used for detecting methimazole in real samples. Current Se doping strategy simplifies the fabrication process of high performance specific nanozyme and promises great potential for environmental analysis.