Evaluation study on separation efficiency of E.coli O157：H7 using a new magnetic bioseparator with magnetic nanobeads

Immune magnetic separation is a new method for separation and concentration of foodborne pathogens.The conventional magnetic separator with low strength and gradient could not capture magnetic beads in nano sizes.This study developed a magnetic bioseparator based nano-sized magnetic beads and it was evaluated using E.coli O157H7as model and conventional standard method,colony counting,for the determination of E.coli cells.Three different sizes of magnetic nanoparticles with the diameters of 30 nm,100nm and 180 nm were used for separation of E.coli cells at the concentrations of 102-106 CFU·mL-1.When the magnetic separation times were no less than 60 min,60sand 40 srespectively,the capture efficiency of E.coli cells was no less than 95%.The relative standard deviations for parallel tests were less than 7.0%.