Dual-stabilizer-capped CdSe quantum dots for “Off–On” electrochemiluminescence biosensing of thrombin by target-triggered multiple amplification

Abstract

In this work, new dual-stabilizer-capped CdSe quantum dots (QDs) with unique electrochemiluminescence (ECL) were prepared, and used to design a promising “off–on” ECL biosensor for highly sensitive assay of thrombin by target-triggered multiple amplification for the first time. New poly(diallyldimethylammonium chloride) (PDDA)–graphene oxide (GO) nanocomposites with good electroconductibility and much surface area was used to assemble a large number of CdSe QDs on the electrode, showing excellent ECL and stability. The ECL of CdSe QDs was efficiently quenched by gold nanoparticles (off state), the presence of target thrombin resulted in the generation of numerous DNA sequences (t1) by using multiple DNA cycle amplification techniques. Subsequently, the specific hybridization of abundant t1 to the quencher probe caused significantly amplified ECL enhancement (on state), which was used for highly sensitive detection of thrombin. More importantly, the biosensor with the dual-stabilizer capped CdSe QDs demonstrated highly intense ECL emission, and the DNA devices by the cleavage reaction were cycled for multiple rounds, which greatly amplified the ECL signal and much improved the detection sensitivity. The developed assay protocol also shows high selectivity for the target and can be performed in homogeneous solutions. These distinct advantages make it a potential platform for detecting various types of biomolecules. This flexible biosensing system exhibits excellent performance in real human serum assay, which has wider potential applications than other ECL reagent-based system.