Synergistic amplification effect for electrochemiluminescence immunoassay based on dual coreactants coupling with...

Sensitive electrochemiluminescence (ECL) bioanalysis could be achieved by exploring the amplification principle or strategy. This work described the first proof-of-concept study for coupling dual coreactants (K₂S₂O₈ and H₂O₂) with localized surface plasmon resonance (LSPR) of silver nanoparticles (AgNPs) enhancement as an effective signal amplification strategy for ECL immunosensor. Specifically, AgNPs as an excellent conductor and nanocarriers were employed as the antibody (Ab₂) immobilization film on the glassy carbon electrode (GCE) for the subsequent sandwich-type immunoreaction between the target protein and antibody (Ab₁)-g-C₃N₄ resulted in the ECL generation. On the one hand, due to the perfect overlap between the plasmon absorption spectrum of AgNPs and the ECL emission spectrum of g-C₃N₄, a plasmon-enhanced ECL phenomenon was proved in g-C₃N₄-AgNPs system result from high efficient energy transfer. On the other hand, it was validated that the ECL signal of the constructed biosensor was greatly strengthened by K₂S₂O₈ and H₂O₂ as dual coreactants, which was ca. 3.5 and 7 times stronger than that of K₂S₂O₈ or H₂O₂ as an individual coreactant, respectively. Consequently, this synergistic amplified ECL immunosensor performed well with great stability and repeatability for squamous cell carcinoma antigen (SCCA) detection in the range from 0.001 to 1000 ng mL^-1. Considering the favorable analytical feedback in actual serum samples assay, this proposed method indicates a great potential for bioassay application.