A S/N co-doped carbon-based peroxidase-like nanozyme for the detection of AChE and organophosphorus pesticides

Herein, a novel S/N co-doped carbon-based nanozyme （S/N-Fe₈₀₀） with peroxidase-like properties was synthesized by doping thiourea into Fe MOF and introducing g-C₃N₄ for pyrolysis. Generated by enzymatic cascade with acetylcholinesterase (AChE) involved, H₂O₂ could react with S/N-Fe₈₀₀ to generate reactive oxygen species (ROS). O-Phenylenediamine (OPD) could be catalyzed by ROS, resulting in the production of 2,3-diaminophenazine (DAP) with a fluorescent emission at 564 nm. The organophosphorus pesticides (OPs), including triazophos (Taz) and phosmet (Pho), have the capacity to impede the enzymic catalytic reaction of AChE, thus affect the fluorescence of DAP. A rapid and sensitive sensing platform that allows for the simultaneous determination of AChE, Taz and Pho was successfully established through monitoring the fluorescence at 564 nm. The limit of detection (LOD) for AChE, Taz and Pho were determined to be 0.035 U/L, 0.047 ng/mL and 0.072 ng/mL, respectively. This method achieved satisfactory results in the human serum and common agricultural products.