Novel Ce-based coordination polymer nanoparticles with excellent oxidase mimic activity applied for colorimetric assay to organophosphorus pesticides

Cerium, as a lanthanide, has attracted considerable interest because of its excellent catalytic activity. Here, we propose a novel cerium-based coordination polymer nanoparticles named DPA–Ce–GMP, which have excellent oxidase-mimicking properties. Furthermore, a colorimetric probe that can act as an inhibitor to suppress the activity of acetylcholinesterase (AChE) was developed for detecting organophosphorus pesticides (OPs). DPA–Ce–GMP catalyzes colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue color, and AChE catalyzes acetylthiocholine to produce thiocholine (TCh), which can weaken DPA–Ce–GMP-catalyzed TMB. After the addition of OPs, the enzymatic activity of AChE was inhibited to produce less amount of TCh, resulting in more DPA–Ce–GMP-catalyst oxidized TMB to show an increasing blue color. Dichlorvos, as the samples, with the limit of 0.024 μg/L. Overall, we believe that the colorimetric probe can be used for the rapid, low-cost, and large-scale field detection of OPs in food samples.