PNNL

Abstract

It is important to develop a portable biosensor for simple, sensitive, selective, and quantitative analysis of 3,5,6-trichloropyridinol (TCP) because TCP is a metabolite of chlorpyrifos, one of the most widely used organophosphorus pesticides in agriculture across the world. In this article, a novel and portable fluorescent sensor that integrates immunochromatographic test strip assay (ITSA) with a quantum dot (QD) label and a test strip reader was described in this study for simple, rapid, and sensitive biomonitoring of an organophosphorus pesticide metabolite. The principle of the immunosensor is based on a competitive immunoreaction that was performed on the immunochromatographic test strip where analytes compete with competitors (a QD-conjugated analog) to bind to antibodies on a test zone. Captured QDs serve as signal vehicles for fluorescent readout. QD-TCP conjugate was synthesized and characterized with XPS and fluorescence spectroscopy. Some parameters (e.g. the amount of QD modified TCP and immunoreaction time) that govern sensitivity and reproducibility of ITSA were optimized with TCP. Under optimal conditions, the sensor has a wide dynamic range and is capable of detecting a minimum 1.0 ng/mL TCP standard analyte in 15 min. The immunosensor has been successfully applied for detection of TCP spiked in rat plasma with average recovery of 102.0%. Results demonstrate that this sensor provides a rapid, clinically accurate, and quantitative tool for TCP detection and shows great promise for in-field and POC quantitative testing and screening for metabolite biomarkers, e.g. TCP, for human exposed to pesticides.