Effect of physiochemical property of Fe3O4 particle on magnetic lateral flow immunochromatographic assay

In this study, Fe3O4 nanoparticles were prepared as bio-probes in lateral flow immunochromatographic immunoassay (LFIA) system for rapid and quantitative detection of Vibrio parahaemolyticus (VP). The relationship was discussed between the assay performance and material characteristics of the probe, including particle size, size distribution and magnetic property. Comparison data with two commercial magnetic particles showed that the bio-probe based on homemade Fe3O4 particle produced the highest magnetic resonance, smaller size and good colloidal stability, a key to obtain good detection performance. Better quantitative signals were achieved by the Fe3O4 particles with small particle size and spherical geometry, that yielded a detection limit of 1 × 105 CFU/mL VP. Whereas a larger diameter greater than 1.0 μm and a broad size distribution obviously impede the fluid dynamic behaviors during the chromatography on the test strip surface, causing a false-positive result. Our study shows that physiochemical property of Fe3O4 particle is key control element for developing high performance LFIA. Magnetic bio-probe in LFIA shows great promise in highly sensitive, rapid qualitative and quantitative on-site test of hazardous substances.