An immunosensor based on magnetic relaxation switch and polystyrene microparticle-induced immune multivalency enrichment system for the detection of Pantoea stewartii subsp. Stewartii

A rapid, sensitive, and simple immunosensor has been developed for the detection of Pantoea stewartii subsp. Stewartii (Pss). This immunosensor combines magnetic relaxation switch (MRS) assay with polystyrene microparticle-induced immune multivalency enrichment system. Comparing to conventional enzyme-linked immunosorbent assay (ELISA), the immunosensor developed in this study provides higher sensitivity and requires less analysis time. The detection limit of Pss obtained by immunosensor was determined to be 10(3)cfu/mL, 50 times lower than that by ELISA (5×10(4)cfu/mL), while the analysis time required by immunosensor is 30min much shorter than that by ELISA. The average recoveries studied with Pss at various spiking levels ranged from 85.5% to 93.4% with a relative standard deviation (RSD) below 6.0%. No cross-reaction with the other five strains was found, demonstrating a good specificity of Pss detection. The results showed that the MRS immunosensor combined with PS-induced immune multivalency enhancement system is a promising platform for the determination of large biological molecules due to its high sensitivity, specificity, homogeneity, and speed.