Bifunctional peptide-biomineralized gold nanoclusters as electrochemiluminescence probe for optimizing sensing interface

Non-competitive immunoassay systems often are used for detecting biomarkers, and their sensitivity depends on the arrangement mode of substrate and the property of signal label. In this work, a novel electrochemiluminescence (ECL) sensing platform utilizing split antibody fragments (Fab')(2) as substrate and self-designed nonapeptide H2N-CCYHWRGWV-COOH (CCYTAR) biomineralized gold nanocluster (Au NCs) as label was fabricated. Fixated (Fab')(2) domains on gold-plated electrodes via Au-S bonds could form well-ordered microarray with higher immune affinity than random antibody fixation. Besides, The CCYTAR nonapeptide not only could function as reductant and capping agent for synthesizing Au NCs, but also act as specific antibody immobilizer for recognizing Fc domains specifically. Also, related experiments verified that CCY and TAR, two independent regions of bifunctional nonapeptide, acted independently. In the end, the Cyfra(21-1) is employed as target to test the feasibility of all strategies, and the results confirmed that the sensing platform could be promising candidate for ECL-based biosensor fabrication in the future.