Pesticide detection using a core-shell nanoparticle coated optical fiber sensor in environmental samples.

Abstract

Nowadays, the use of pesticides to increase crop yield and quality is widespread. However, they contaminate water, food, and soil and threaten human health and ecosystems due to their bioaccumulation and persistence. The food we eat is grown using pesticides, harming human health. Therefore, developing a cost-effective, rapid and sensitive monitoring protocol for detecting pesticides in water and soil is highly desirable, especially since rice is widely consumed and produced in India. In this study, core-shell structured copper-silver nanoparticles (Cu-Ag CSNPs) were chemically synthesized using a two-step process. The CSNPs were then thoroughly characterized using XRD, SEM, EDS, TEM, XPS, FTIR, and UV-Vis spectroscopy analyses. These CSNPs were then exploited as a plasmonic sensing unit to design a fiber sensor for detecting imidacloprid (IMD) pesticides. Due to strong chemical interactions between the CSNPs and IMD, distinct spectral shifts were observed over a vast range of concentrations (1200 µM-0.001 µM) due to the LSPR effect. The developed sensor has been employed for both laboratory and real sample analyses, and has demonstrated successful selectivity in real environmental matrices like river water, rice, and agricultural soil, and acheived a high recovery percentage. The novelty of this work lies in the first integration of Cu-Ag CSNPs into an LSPR-based optical fiber platform for ultra-trace IMD detection, achieving a detection limit at the picomolar level.

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