Electrochemical detection of methyl-paraoxon based on bifunctional cerium oxide nanozyme with catalytic activity and signal amplification effect

Abstract

A new electrochemical sensor for organophosphate pesticide (methyl-paraoxon) detection based on bifunctional cerium oxide (CeO 2 ) nanozyme is here reported for the first time. Methyl-paraoxon was degraded into p -nitrophenol by using CeO 2 with phosphatase mimicking activity. The CeO 2 nanozyme-modified electrode was then synthesized to detect p -nitrophenol. Cyclic voltammetry was applied to investigate the electrochemical behavior of the modified electrode, which indicates that the signal enhancement effect may attribute to the coating of CeO 2 nanozyme. The current research also studied and discussed the main parameters affecting the analytical signal, including accumulation potential, accumulation time, and pH. Under the optimum conditions, the present method provided a wider linear range from 0.1 to 100 μmol/L for methyl-paraoxon with a detection limit of 0.06 μmol/L. To validate the proof of concept, the electrochemical sensor was then successfully applied for the determination of methyl-paraoxon in three herb samples, i.e., Coix lacryma-jobi, Adenophora stricta and Semen nelumbinis. Our findings may provide new insights into the application of bifunctional nanozyme in electrochemical detection of organophosphorus pesticide.

Nanozymes for Environmental Pollutant Monitoring and Remediation

“…Recent years have seen the emergence of nanozymes for the monitoring and degradation of pesticide residues on plants, crops, soil and water samples. Some of the strategies for pesticide detection are reliant on enzyme-like inhibition assays [ 138 , 139 , 140 ] or exploit the phosphatase-like activity for pesticide degradation [ 141 , 142 , 143 ]. Those that are based on the phosphatase-like activity are type I nanozymes involving nanoceria [ 141 , 142 , 143 ], whereas those based on the peroxidase-like activity are mainly type I Fe 3 O 4 nanoparticles [ 140 , 144 , 145 ] or type II metal particles [ 138 , 146 , 147 , 148 ].…”

“…Electrochemical detection of the degradation product of methyl-paraoxon has also been demonstrated using nanoceria. Sun et al [ 143 ] have exploited the bifunctionality of nanoceria as a phosphatase mimic to degrade methyl-paraoxon to p -nitrophenol, followed by electrochemical detection of p -nitrophenol at a nanoceria-modified glassy carbon electrode ( Figure 16 ). The electrochemical method was highly sensitive, with a methyl-paraoxon detection limit of 0.06 μM.…”

“… Schematic of nanoceria as a bifunctional material for catalysis and electrochemical detection of methyl-paraoxon. (Reprinted with permission from [ 143 ]. Copyright © The Authors.…”

Nanozyme-Participated Biosensing of Pesticides and Cholinesterases: A Critical Review

“…In these assays, OPs are not only the analyte, but also act as a reagent to generate signals. The representative phosphatase-like nanozymes include Ce-based [103][104][105] and Zr-based materials [106][107][108]. For example, to realize the determination of pesticides, Wu et al prepared a ZrO 2 /CeO 2 /PAA nanocomposite with remarkable phosphatase-mimicking activity, which could degrade methylparaoxon to p-nitrophenol with a yellow color for colorimetric detection [105].…”

Metal–Organic Frameworks (MOFs) Based Analytical Techniques for Food Safety Evaluation

“…Consequently, the widespread or even excessive use has led to pesticide poisoning accidents and accumulated residues in soil, ground water and food that are essential to human beings [40]. Therefore, there is an urgent need to develop facile and reliable analytical methods of detecting OPP residues for the food safety and human health [41][42][43][44]. To detect trace amount of OPPs in real food and environmental samples, a facile and low-cost Zr-MOF was established [45].…”