A fluorescence biosensor for organophosphorus pesticide detection with a portable fluorescence device-based smartphone

An innovative fluorescence biosensor was successfully developed to detect organophosphorus pesticide (OPs) by utilizing smartphone technology. The assay relied on the enzymatic activity of alkaline phosphatase (ALP), which facilitated the conversion of L-ascorbic acid 2-phosphate sesquimagnesium salt hydrate (AAP) into L-ascorbic acid (AA). The AA that generated was then reacted with o-phenylenediamine (OPD) to yield a fluorescent marker identified as 3-(1,2-dihydroxyethyl)furo[3,4-b]quinoxalin-1(3H)-one (DFQ). A novel bandpass approach was specifically developed for a smartphone that was integrated with a customized portable fluorescence device to measure the fluorescence emission of DFQ. The device has a unique application that converts the fluorescence intensity into an RGB signal. In the presence of OPs, malathion was chosen as the representative of the OPs substance; the enzymatic activity of the ALP was inhibited, resulting in a decrease in fluorescence intensity, which was proportional to the concentration of malathion. Smartphones can be used to measure fluorescence emission, offering a calibration sensitivity more than 70 times higher than that of conventional spectrofluorometer. The recently developed methodology can be employed to identify malathion within the concentration range of 0.1–1 ppm, with a detection limit of 0.05 ppm. The practical applicability of the method was established using vegetable samples, and the acquired results were in good agreement with those obtained using the standard HPLC approach. This innovative method provides both portability and accuracy, while also exhibiting a notable degree of sensitivity in detecting trace amounts of OPs.