Streptavidin-exposed magnetic nanoparticles for lectin magnetic separation (LMS) of Staphylococcus aureus prior to three quantification strategies

摘要

A lectin magnetic separation (LMS) method for Staphylococcus aureus (S. aureus) was developed with the aim to improve the efficiency of magnetic nanoparticles and to expand the scope of bacterial recognition. Poly(ethylene glycol) (PEG)-mediated magnetic nanoparticles modified with streptavidin (MNP-PEG-SA) were synthesized and then applied to a two-step LMS based on the use of wheat germ agglutinin (WGA). Three specific methods for S. aureus detection (suitable for different requirements including detection time and sensitivity) were designed. The new LMS has improved anchoring efficiency (compared to two-step LMS methods) and requires a reduced number of magnetic particles. The Baird-Parker (B-P) method can detect S. aureus with a detection limit of 3 x 10(0) CFU center dot mL(-1) within 15 h; the polymerase chain reaction (PCR) method can be finished within 4 h, with the lowest detection limit (LOD) of 3 x 10(2) CFU center dot mL(-1). The LOD of HRP-pig IgG-based colorimetric method is 3 x 10(5) CFU center dot mL(-1), and the method only lasts for 2 h. If combined with specific detection methods, it meets different needs for rapid detection of S. aureus.