An in situ quenching electrochemiluminescence (ECL) biosensor sensitized with the aptamer recognition-induced multi-DNA release was designed for pathogenic bacterial detection. Benefitting from the high binding ability of the aptamer to targets and large enrichment capacity of magnetic bead separation, the proposed sensing system not only exhibited outstanding identification to Staphylococcus aureus (S. aureus) among various bacteria, but also released abundant signal transduction DNAs. One S. aureus initiated the dissociation of four kinds of DNA sequences, achieving a one-to-multiple amplification effect. These multi-DNA strands were further hybridized with capture DNA, which were assembled to an electrode modified with Ru(bpy)32+-conjugated silica nanoparticles (RuSi NPs). Then, glucose oxidase (GOD) was introduced via the functional conjugation of GOD-multi-DNA, leading to the presence of H2O2 by in situ catalysis of GOD on glucose. Relying on the ECL quenching of H2O2 in the Ru(bpy)32+ system, S. aureus was quantified with a linear range from 10 to 107 CFU/mL. In addition, the negative results of non-target bacteria and good recovery efficiency in real samples revealed the system's remarkable selectivity and potential application in infectious food tests.
Keywords: Aptamer; ECL; In situ quenching; Multi-DNA; S. aureus.
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