Design and development of ISFET-based portable microalgal biosensor using Chlorella sp. for the detection of organophosphorus pesticide.

The study is focused on fabricating a portable potentiometric biosensor using Chlorella sp. immobilized on TaO Ion-Sensitive Field Effect Transistor (ISFET) for detecting organophosphorus pesticides (OPPs). The developed biosensor detection mechanism is based on pesticide-induced inhibition of alkaline phosphatase enzyme activity, with a change in ascorbic acid production as a product signal. The sensitivity, selectivity, and detection limit of the biosensor were evaluated for its efficacy in detecting a range of organophosphorus pesticides, including acephate, triazophos, chlorpyrifos, and malathion. The biosensor achieved a detection limit of as low as 10 M for acephate and triazophos, showing remarkably high sensitivity and selectivity with linear responses across a wide concentration range of 10 to 10 M, whereas for chlorpyrifos, it is in the range of 10 to 10 M. However, the results for malathion showed reduced sensitivity and inconsistent trends. The optimization study of various parameters for efficient detection includes algal concentration (20 μL), substrate concentration (0.4 mL of PAA), and response time (4 min). To validate the developed biosensor, real-time soil sample analysis was compared against High-Performance Liquid Chromatography (HPLC). The prototype demonstrated is cost-effective, portable, and offers outstanding reproducibility and sensitivity, suggesting its potential utility for on-site pesticide detection applications.