New kid on the block: Cerium oxide nanozyme joins the pesticide detection taskforce, according to Journal of Pharmaceutical Analysis study

Organophosphates, like methyl-paraoxon, have grown in prominence as effective pest repellants for crops like cotton and legumes. Studies have shown that these pesticides remain in trace concentrations in the final produce, and cause severe ill effects in humans, including neuro-, embryo-, geno-, cyto-, and immunotoxicity. Hence, detecting and removing even trace amounts of organophosphates in consumed plant products is imperative.

Pesticide detection technologies are growing at a rapid pace worldwide. In this regard, a group of scientists in China have taken up the baton to advance pharmaceutical analysis of organophosphates in plants, beginning with methyl-paraoxon. Considering the therapeutic potentials of indigenous herbs, the scientists were concerned if these plants could be contaminated by methyl-paraoxon. As such, under the guidance of Dr. Peng Li, an expert in Chinese medicine and pharmaceutical analysis, from the Institute of Chinese Medical Sciences, University of Macau, China, they scouted for potential sensitive methyl-paraoxon detection methods.

Accordingly, their painstaking research to find detection methods led them to cerium oxide nanozyme. Speaking about their detection methodology, Dr. Li exclaims, “Under the optimized conditions, we achieved desirable recoveries for different herbal samples using cerium oxide nanozyme. We believe that our electrochemical method can be practically applied in the rapid detection of pesticide residues.” Their findings have been made public as a research article, which became available online on 8^th September 2020, and was subsequently published in Volume 11 and Issue 5 of the Journal of Pharmaceutical Analysis on 31^st October 2021.

To arrive at the methyl-paraoxon detection tool, the scientists modified glassy carbon electrode using the cerium oxide nanozyme. Using methods like cyclic voltammetry, they confirmed that there is a significant signal enhancement owing to the presence of cerium oxide nanozyme.

Next, they used this electrode to detect methyl-paraoxon, degraded to p-nitrophenol using the same nanozyme. Their analysis showed that the developed electrochemical method provided an unprecedented wider linear range, from 0.1 to 100 mmol/L, and a detection limit of 0.06 mmol/L for methyl-paraoxon—quite respectable values, so to say.

Further, they validated the proof of concept, which is electrochemical detection of methyl-paraoxon using bifunctional cerium oxide nanozyme, using three Chinese herb samples—Coix lacryma-jobi, Adenophora stricta, and Semen nelumbinis.

Dr. Li and fellow scientists believe that the design can be further improved by supporting the cerium oxide nanozyme on porous materials, or on three-dimensional materials with a large surface area, to perform dual functions of catalysis and detection simultaneously, rather than in isolation.

Furthermore, they are hopeful about the extended application of the cerium oxide nanozyme-based electrochemical detection method. Speaking for the entire team, Dr. Li states, “With steady methodological improvement, we believe that our method, with its excellent electrochemical performance, can be used to detect other trace substances in a variety of solutions in the near future.”

Overall, the study has paved the way for advanced research on effective detection of pesticides in various materials used for human consumption. Although we may not yet be closer to a completely organic future where our dependence on chemicals for growing our food is entirely eliminated, with such advanced technologies in place and adoption of monitoring practices, the judicious use of pesticides may be ensured, which could ultimately facilitate the realization of our organic, chemical-free future.

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Reference

DOI: https://doi.org/10.1016/j.jpha.2020.09.002

Authors: Yuzhou Sun ¹, Jinchao Wei ^1,2, Jian Zou ^2,3, Zehua Cheng ¹, Zhongming Huang ⁴, Liqiang Gu ¹, Zhangfeng Zhong ¹, Shengliang Li ⁴, Yitao Wang ¹, Peng Li ^1,

Affiliations:

¹State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, China.

²Institute of Traditional Chinese Medicine & Natural Products, College of Pharmacy, Jinan University; Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, China.

³Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, China.

⁴Center of Super-Diamond and Advanced Films (COSDAF) and Department of Chemistry, City University of Hong Kong, China

About Dr. Peng Li

Dr. Peng Li is an Associate Professor at the State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, China. Dr. Li is an expert in the field of pharmaceutical analysis. His research focuses on quality analyses of Chinese medicines. He has worked as an author for four books, related to his work on Chinese medicines. Also, he has more than 30 publications in reputed national and international journals, to his credit. He received his M.Sc and PhD from the University of Macau.