A portable turbidity-based sensor constructed <i>via</i> inhibition of lipase activity for point-of-use testing of dichlorvos pesticides

Point-of-use testing techniques are very significant in the fields like food safety and environmental monitoring. Here, we propose a portable turbidity-based sensor for point-of-use quantification of dichlorvos (DDVP) pesticides <i>via</i> inhibition of lipase activity to regulate the formation of fatty acid calcium precipitates. Typically, the fatty acid produced by <i>Candida antarctica</i> lipase B (CaLB)-catalytic hydrolysis of Tween-20 can combine with calcium ions to form precipitates, accompanied by heightened turbidity. DDVP can effectively inhibit the activity of CaLB, resulting in reduced turbidity. The concentration of DDVP is thereby determined by monitoring the variation of turbidity using a portable nephelometer. The sensing strategy is applied for quantitative analysis of DDVP in food samples with satisfactory results. The portable nephelometer is handheld, user-friendly, and cost-effective and also all reagents are commercially accessible. As a result, the proposed turbidity-based sensor has great potential for point-of-use detection of DDVP in practical applications. This work exploiting CaLB-mediated turbidity as a sensing readout signal also provides a new insight to develop point-of-use testing techniques.