Apple polysaccharide stabilized palladium nanoparticles for sensitive detection of organophosphorus pesticide.

The widespread application of organophosphorus pesticides (OPs) has inflicted significant damage on human well-being and food security. Hence, it is imperative to develop a friendly and accessible biosensor for the detection of OPs. Herein, apple polysaccharide (AP) stabilized palladium nanoparticles (AP-PdNPs) with a particle size of 2.75-5.95 nm were prepared using AP as a stabilizer and reducing agent. AP-PdNPs exhibited good peroxidase-like activity and effectively decomposed HO to ·OH, which catalyzed the 3,3',5,5'-tetramethylbenzidine system to become blue. The catalytic kinetics of AP-PdNPs conformed to the typical Michelis-Menten equation. Furthermore, OPs directly inhibited the peroxidase-like activity of AP-PdNPs. Thus, a highly effective colorimetric biosensor was developed for the detection of OPs. The detection range of the biosensor was 0.050 μg/L - 200 mg/L, and the limit of detection was extremely low to 0.010 μg/L. Compared with other nanomaterials, the detection platform based on AP-PdNPs can effectively detect organophosphorus pesticides without coupling natural enzymes；this method is more economical and practical. Therefore, this established method explores good perspective for the detection of OPs.