AgNPs-3D nanostructure enhanced electrochemiluminescence of CdSe quantum dot coupled with strand displacement amplification for sensitive biosensing of DNA.

A novel strategy using Ag nanoparticles-3D (AgNPs-3D) nanostructure enhanced electrochemiluminescence (ECL) of CdSe quantum dots (QDs) coupled with strand displacement amplification (SDA) for sensitive biosensing of DNA was successfully designed. The prepared CdSe QDs with intense ECL were assembled on the poly (diallyldimethylammonium chloride) (PDDA) graphene oxide (GO) nanocomposites modified electrode, then gold nanoparticles (NPs) as the quenching probe was conjugated to the QDs, ECL signal was efficiently quenched. The target DNA induced cycling SDA and generated a large number of DNA s1. The released DNA s1 could open the hairpin DNA with quenching probe. So the presence of low levels of target DNA can potentially result in a significant enhancement of ECL signal. Furthermore, large number of AgNPs were then in situ reduced in the 3D DNA skeleton on the electrode, which dramaticlly enhanced ECL signal of QDs owing to the excellent electrical conductivity, and the much amplified ECL signal change has a quantitative relation with the target DNA. So by combining the AgNPs-3D nanostructure and cycling SDA to achieve greatly amplified detection of DNA, the promising ECL strategy could provide a highly sensitive platform for various biomolecules and has a good prospect for clinical diagnosis in the future.