Pt-Ni(OH)2 nanosheets amplified two-way lateral flow immunoassays with smartphone readout for quantification of pesticides.

Excessive use of herbicide and insecticide causes bioaccumulation in the environment and increases potential toxicity for people and animals. Portable systems for rapid assays of herbicide and insecticide residues have attracted prominent interests. Here, we developed a two-dimensional (2D) Pt-Ni(OH)2 nanosheets (NSs) amplified two-way lateral flow immunoassay (LFI) with a smartphone-based readout for simultaneous detection of acetochlor and fenpropathrin. The 2D Pt-Ni(OH)2 NSs were synthesized and used as the enhanced signal label in the immunoassay due to their high peroxidase-like activity and low migration speed. The two-way LFI was designed to eliminate potential cross-reaction between two targets. Portable detection system was developed based on a smartphone-based readout, which scans the LFI and provides the accurate testing result. The universal use of smartphones makes the developed platform suitable for cheap and on-site applications. Using the integrated platform, detection of acetochlor and fenpropathrin simultaneously was successfully achieved with the detection limits of 0.63 ng/mL and 0.24 ng/mL, respectively. To confirm the performance of the on-site application, we detected 10 non-spiked samples and 3 spiked samples. The obtained detection results were consistent with the data from gas chromatography analysis. The estimated recoveries ranged from 97.12% to 111.46%, indicating the practical reliability of our developed assay. The developed smartphone-based platform exhibits enhanced sensitivity, which provides a promising technique for on-site, multiplex, highly sensitive detection of pesticides.