Electrochemiluminescent quaternary Cu-Zn-In-S nanocrystals as a sensing platform: Enzyme-free and sensitive detection of the FLT3 gene based on triple signal amplification

A new near-infrared electrochemiluminescence resonance energy transfer (NECL-RET) strategy for enzyme-free amplified DNA detection was designed. In this strategy, the quaternary Cu-Zn-In-S nanocrystals (NCs) were applied as the ECL donor and gold nanostars (AuNSs) were used as the acceptor. The flowerlike MoS2/GO/o-MWNTs nanostructure was synthesized and used as an outstanding substrate to immobilize the NCs. ECL measurements demonstrated that the NCs assembled on the MoS2/GO/o-MWNTs film resulted in ECL intensity amplified by ~2.5-fold compared to that of the NCs assembled directly on the GCE. The Sem used here was not only as a coupling reagent to attach the NCs on the MoS2/GO/o-MWNTs but also as a novel co-reaction accelerator to enhance the ECL intensity. In addition, we designed two hairpin DNA probes of H1 and H2, and based on the target-catalyzed hairpin assembly, tDNA could trigger the hybridization of the H1 and H2-AuNSs to be further released to initiate the next hybridization process to capture a larger number of H2-AuNSs on the electrode surface, which resulted in the quenching of the NCs ECL emission. Therefore, a dramatic increase in the ECL quenching efficiency proportional to the tDNA concentration was achieved. The linear range for tDNA detection was from 10 aM to 10 pM with a detection limit down to 10 aM. This design introduces the new concept of triple signal amplification into ECL determination, and it shows promise to be extended to provide a highly sensitive platform for various target DNA.