Bioluminescence assay for rapid detection of live Staphylococcus aureus based on the enrichment of egg yolk antibody modified magnetic metal organic framework immunobeads

Abstract

Specific and rapid detection of live Staphylococcus aureus (S.A) in environmental and food samples is critically important for protecting human health. In order to fulfill this purpose, two kinds of novel egg yolk antibody (IgY) immobilized immunomagnetic beads (IMBs; mSiO₂-IgY and mMOF-IgY), with core–shell mSiO₂ and mMOF as substrate, were prepared for selectively enriching S.A from samples. Furthermore, the IMBs with captured S.A were collected and re-dissolved in 0.5 mL PBS. After that, a cotton swab coated with sodium dodecylsulfate (SDS) was put in the solution to lyse S.A cells and emit ATP bioluminescence of the luciferin/luciferase system. Finally, a portable bioluminescence detector was used for quantification of ATP corresponding to S.A concentration. The results demonstrated that mMOF-IgY can enrich more S.A than mSiO₂-IgY and emit a stronger signal. The reasons may be due to the higher immobilization amount of IgY on the IMBs. Under optimal conditions, the calibration line of S.A concentration was 10–10⁵ CFU mL⁻¹ by mMOF-IgY within 30 min. The low detection limit of S.A was 3 CFU mL⁻¹. The results demonstrated that the assay takes much shorter time than plate counting. Its portability and excellent detection capability are suitable for rapid monitoring of specific pathogens in foods.