Rapid pesticide detection based on FeS2 NSs with high practicality in actual environments

The overuse of organophosphorus pesticides (OPPs) poses a severe threat to food safety and human health, making the monitoring of OPPs an urgent necessity. Here, we developed a sensitive colorimetric sensing system for OPP monitoring based on the peroxidase-mimicking activity of FeS₂ NSs. In this strategy, alkaline phosphatase (ALP) catalyzes the production of ascorbic acid (AA) from ascorbic acid 2-phosphate. AA scavenges hydroxyl radicals (˙OH) and subsequently reduces the generation of the colorized substrate oxidized TMB in the FeS₂–TMB–H₂O₂ catalytic system. On the other hand, OPPs, as ALP activity inhibitors, can prevent the formation of AA by inactivating the ALP activity and restoring the colorimetric route. Hence, the concentration of OPPs is positively associated with the absorbance of the sensing system. The limit of detection is defined as low as 0.46 nM with the response time as low as 40 minutes at room temperature. Moreover, the high anti-interference stability in pond water and leaf surface washing fluid also makes this detection system appropriate for portable, fast, and reliable detection, especially in field water samples. This proposal not only exhibits good selectivity and sensitivity but is also simple to operate and low-cost, demonstrating its potential for reliable applications for OPPs.