Silver Nanoclusters for High-Efficiency Quenching of CdS Nanocrystal Electrochemiluminescence and Sensitive Detection of microRNA

In this work, oligonucleotide-encapusulated silver nanoclusters were applied in the electrochemiluminescence (ECL) system of CdS nanocrystals (NCs)/ K2S2O8 based on dual ECL quenching effects. We found that the ECL emission of CdS NCs matched well with the absorption band of oligonucleotide encapsulated Ag nanoclusters, which could act as the energy acceptor of CdS NCs ECL so as to lead to an effective ECL resonance energy transfer (RET). On the other hand, the Ag nanoclusters could also catalyze electrochemical reduction of K2S2O8, resulting in increased consumption of ECL coreactant near the working electrode and decreased ECL intensity from CdS NCs. On the basis of the dual ECL quenching effects, a sensitive ECL biosensor for detection of microRNA was successfully achieved with a wide linear range from 10 fM to 100 pM.