On‑site sensing of pesticides using point‑of‑care biosensors: a review

Ever increasing demand for food and agricultural resources have led to escalation of pesticide poisoning and environmental hazards. An efficient system for pesticide detection is a constant endeavour and several technologies are working hand in hand to generate effective biosensors for various classes of pesticides. Innovative technologies are being developed for pesticides detection which overcome issues such as time and costs involved in sample preparation. Moreover, improvements in ease of operation and better sensitivity have been achieved using techniques such as fluorescence spectroscopy and electrochemical methods. Many tools such as aptamers, gold nanoparticles, quantum dots, molecularly imprinted polymers and, antibodies are used to develop hybrid biosensors where the sensitivity is increased several folds and limit of detection is as low as 0.1 pM. The time of detection is reduced to minutes along with simultaneous detection of multiple pesticides using the biosensors. We reviewed the latest biosensors developed which can be utilized for on-site sensing and optical biosensors are at the forefront of technology with advantages such as easy protocols, simple operation, high sensitivity, broad linearity range and cost-effectiveness. Colorimetric and fluorescence biosensors have rapid detection of pesticides with 90% recovery in food and serum samples. Chemiluminescence utilising biosensors have low detection time while photoluminescent sensors are highly sensitive and can be easily combined with smartphones for real-time detection. Many commercially available Surface Enhanced Raman Scattering (SERS) substrates are also present. For a cost-effective point-of-care biosensor, sample pre-treatment and expensive instrumentation are few hurdles that are conquered in electrochemical sensors. With amperometric, impedimetric and potentiometric techniques used in these biosensors, a low detection limit and time is observed in agriculture, water and food samples containing variety of pesticides. The review covers all the major techniques which can potentially be used for the development of point-of care biosensors such as, colorimetric, fluorescence, chemiluminescence, photoluminescence, surface enhanced Raman scattering and electrochemical in detailed and up-to-date analysis.