Magnetophoretic separation ICP-MS immunoassay using Cs-doped multicore magnetic nanoparticles for the determination of salmonella typhimurium

In this work, a magnetophoretic separation ICP-MS immunoassay using newly synthesized multicore magnetic nanoparticles (MMNPs) was developed for the determination of salmonella typhimurium (typhi). The uniqueness of this method was the use of MMNPs doped with Cs for both separation and detection, which enable us to achieve fast analysis, high sensitivity, and good reliability. For demonstration, heat-killed typhi in a phosphate buffer solution was determined by ICP-MS after the MMNP-typhi reaction product was separated from unreacted MMNPs in a micropipette tip filled with 25% polyethylene glycol through magnetophoretic separation. The calibration curve obtained by plotting 133Cs intensity vs. the number of synthetic standard, showed a coefficient of determination (R2) of 0.94 with a limit of detection (LOD) of 102 cells/mL without cell culturing. Excellent recoveries, between 98–100%, were obtained from four replicates and compared with a sandwich-type ICP-MS immunoassay for further confirmation. [Display omitted] •Magnetophoretic separation ICP-MS immunoassay was developed for typhi determination.•For separation and detection, Cs-doped multicore magnetic nanoparticles were synthesized with proper size and magnetization.•Magnetophoretic separation was optimized at the micropipette tip with PEG medium.•Excellent analytical performance, with high speed and simplicity, was achieved.