A facile label-free electrochemiluminescent biosensor for specific detection of Staphylococcus aureus utilizing the binding between immunoglobulin G and protein A

A facile label-free electrochemiluminescent (ECL) biosensor was developed for detection of Staphylococcus aureus ( S. aureus ) based on the specific binding between Fc region of immunoglobulin G (IgG) and S. aureus protein A (SPA) in the cell wall. Carboxyl graphene, with large surface and excellent electron transfer ability, was used as the carrier of IgG for fabrication of ECL biosensor. This biosensor was constructed by depositing carboxyl graphene/porcin IgG composite on the surface of a glassy carbon electrode. The specific reaction between SPA and IgG resulted in a decrease of ECL signal because the bound S. aureus interrupted the interfacial electron transfer and hindered the diffusion of the ECL active substances. The ECL intensity decreased linearly with S. aureus concentrations in the range of 1.0×10 3 –1.0×10 9 colony-forming units (CFU)   mL −1 , with a detection limit of 3.1×10 2   CFU   mL −1 . The whole assay could be accomplished within 70   min when a ready-for-use biosensor was applied. The recovery test for food, environmental and biological samples showed recoveries between 75.0% and 116.7%. This developed biosensor displayed ideal specificity, high sensitivity, facile manipulation, simple fabrication and short assay time, thus provided a new pathway for pathogenic bacteria rapid screening.