Highly Efficient and Selective Biosensing of Malathion Utilizing Bioengineered Nanoplatform Based on Fe₃O₄

Nanobioengineered platforms have emerged as promising candidates for biosensing due to their exceptional surface properties accompanied by enhanced functionalization potential. In this research, biogenically synthesized Fe₃O₄ nanoparticles (NPs) have been utilized to fabricate efficient biosensors for the selective and sensitive detection of malathion pesticides. The structural and physicochemical properties of the Fe₃O₄ NPs were thoroughly validated, ascertaining their stability and suitability for malathion biosensing. The Fe₃O₄ NPs were electrodeposited onto the carbon working electrode of the screen-printed electrode (SPE) via electrophoretic deposition, followed by the immobilization of choline oxidase (ChO) to create the ChO-Fe₃O₄ NPs/SPE nanobioengineered electrodes. This biosensor exhibited remarkable sensitivity and specificity toward malathion, with its performance being governed by diffusion layer dynamics, allowing for the reliable detection of malathion across a broad concentration range. With a detection limit of 1.79 μM and a sensitivity of 98.3 μA μM^-1cm^-2 over a wide linear range of 1-200 μM, the sensor exhibits high analytical performance that is competitive with previously reported malathion sensors. The sensor exhibited excellent selectivity, precision, and long-term stability, demonstrating its suitability for the rapid and accurate quantification of malathion in agricultural and environmental samples. Furthermore, real-sample analysis using spiked soil samples showed high recovery rates (93.9% to 98.4%), confirming the sensor's reliability for practical applications. This eco-friendly and cost-effective approach highlights the potential of biogenic nanomaterials in the development of advanced pesticide sensors, thereby contributing to safer environmental practices and enhanced food quality monitoring.