Advances in optical-sensing strategies for the on-site detection of pesticides in agricultural foods

Synthetic chemical pesticides play a significant role in increasing the overall yield and productivity of agricultural foods by controlling and eradicating pests, insects, and numerous plant-related diseases. The over-spraying of pesticides onto crops has escalated pesticide contamination of food products and water bodies, as well as disturbing ecological and environmental systems. In this regard, developing simple, low-cost, and rapid-sensing strategies and portable devices for the precise, efficient, rapid, and on-site detection of pesticide residues in agricultural fields is indeed necessary and urgently required for the wellbeing and safety of mankind and other species. In this review, we make a comprehensive study of the up-to-date state-of-the-art research progress on the on-site sensing strategies and portable devices for the detection of pesticide residues in agricultural foods using paper-, liquid-, and gel-based optical-sensing techniques. Moreover, we delineate the detailed on-site detection mechanism and sensing behavior of the aforementioned strategies and discuss the challenges and future perspectives associated with the development of optical techniques. Recent scientific and technological studies based on optical sensing strategies such as fluorescence sensors, target-responsive hydrogels, chemiluminescence assay, tube enzyme-linked immunosorbent assay, enzymatic fiber-optic biosensor, phosphorescence, lateral flow immunoassay, double-signal fluorescence strategy, wearable glove-based sensors, and paper-based sensors have made novel advancements and brought scientific insight for the on-site detection of pesticide residues in agricultural foods. This review provides significant insights and future perspectives that might serve as the basis for the design and development of novel optical sensors with applicability in various fields.