Smartphone-enabled magneto-immunofluorescence platform for rapid isomiroestrol detection in plants

This study introduces a portable magneto-immunofluorescence platform for isomiroestrol (IME) detection in plant samples, overcoming limitations of traditional ELISA methods that require extensive washing, blocking steps, and laboratory equipment. The approach utilizes amino-functionalized magnetic nanoparticles for selective IME capture via formaldehyde-mediated Mannich reaction, coupled with a dual-antibody detection system (monoclonal antibodies and horseradish peroxidase-labeled polyclonal antibody (pAb-HRP)). The immunofluorescence detection principle was based on the enzymatic conversion of o-phenylenediamine (OPD) by HRP in the presence of hydrogen peroxide to produce the highly fluorescent 2,3-diaminophenazine (DAP). The fluorescence intensity is measured using a smartphone-based portable device, providing a cost-effective alternative to conventional spectrofluorometers. The method demonstrates excellent linearity (R² = 0.9960) across 0.025-1.5 μg mL^-1, with a 0.021 μg mL^-1 detection limit. Requiring only two washing steps at ambient temperature, this platform significantly reduces analysis time while maintaining analytical performance comparable to standard ELISA techniques. This advancement enables accessible, rapid, and reliable field-based IME detection in plant samples.