Sensitive and rapid amperometric magnetoimmunosensor for the determination of Staphylococcus aureus
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- Esteban-Fernández de Ávila, B., Pedrero, M., Campuzano, S. et al. Anal Bioanal Chem (2012) 403: 917. doi:10.1007/s00216-012-5738-8
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The preparation and characteristics of a disposable amperometric magnetoimmunosensor, based on the use of functionalized magnetic beads (MBs) and gold screen-printed electrodes (Au/SPEs), for the specific detection and quantification of Staphylococcal protein A (ProtA) and Staphylococcus aureus (S. aureus) is reported. An antiProtA antibody was immobilized onto ProtA-modified MBs, and a competitive immunoassay involving ProtA antigen labelled with HRP was performed. The resulting modified MBs were captured by a magnetic field on the surface of tetrathiafulvalene-modified Au/SPEs and the amperometric response obtained at −0.15 V vs the silver pseudo-reference electrode of the Au/SPEs after the addition of H2O2 was used as transduction signal. The developed methodology showed very low limits of detection (1 cfu S. aureus/mL of raw milk samples), and a good selectivity against the most commonly involved foodborne pathogens originating from milk. These features, together with a short analysis time (2 h), the simplicity, and easy automation and miniaturization of the required instrumentation make the developed methodology a promising alternative in the development of devices for on-site analysis.