A novel silver nanocluster in situ synthesized as versatile probe for electrochemiluminescence and electrochemical detection of thrombin by multiple signal amplification strategy

In this work, a novel silver nanoclusters (AgNCs) were in situ synthesized and used as versatile electrochemiluminescence (ECL) and electrochemical (EL) signal probes for thrombin detection by using DNAzyme-assisted target recycling and hybridization chain reaction (HCR) multiple amplification strategy. The presence of target thrombin firstly opened the hairpin DNA, followed by DNAzyme-catalytic recycling cleavage of excess substrates, which could generate large number of substrate fragments (s1). Then these s1 fragments were captured by SH-DNA on the Au nanoparticle-modified electrode, which further triggered the subsequent HCR of the hairpin DNA probes (H1 and H2) to form the long dsDNA. The numerous AgNCs were thus in situ synthesized by incubation the dsDNA template (with cytosine-rich loop)-modified electrode in solution with AgNO3 and sodium borohydride. By integrating the DNAzyme recycling and HCR dual amplification strategy, the amount of AgNCs is dramatically enhanced, leading to substantially amplified ECL and electrochemical signals for sensitive thrombin detection. Importantly, this design introduces the novel AgNCs into versatile ECL and EL bioassays by multiple amplification strategy, thus it is promising to provide a highly sensitive platform for various target biomolecules.