A hybrid immuno-nanoparticle lateral flow assay for field detection of Fosetyl-aluminum

A hybrid immuno-nanoparticle lateral flow assay (H-LFA) was developed for the rapid and sensitive detection of fosetyl-aluminum (fosetyl-Al) residues in rice. The assay employs gold nanoparticles (AuNPs) functionalized with 11-mercaptoundecanoic acid (MA) and goat anti-human IgG to create hybrid probes capable of indirectly detecting Fosetyl-Al via the aluminum ions released under acidic hydrolysis. Upon coordination of Al³⁺ with carboxyl groups on the AuNP surface, nanoparticle aggregation is induced, resulting in a decrease in signal intensity at the test line. The assay exhibited a linear detection range of 0.1-25 μg/mL with a limit of detection (LOD) of 0.08 μg/mL. High precision was demonstrated with intra- and inter-batch %RSD values of 4.76 % and <6.3 %, respectively. Recovery studies in spiked rice samples yielded values ranging from 80.0 % to 101.0 %, which were in good agreement with those obtained using the standard HPLC method. In validation with 48 rice samples, the H-LFA achieved 94.4 % sensitivity and 100 % selectivity. This is the first report of utilizing a hybrid immuno-nanoparticle system in a lateral flow format for fosetyl-Al detection. This assay provides a rapid, cost-effective, and field-deployable alternative to conventional laboratory-based techniques for monitoring pesticide residues in agricultural commodities.