Anodic Electrogenerated Chemiluminescence of Ru(bpy)(3)(2+) with CdSe Quantum Dots as Coreactant and Its Application in Quantitative Detection of DNA

In the present paper, we report that CdSe quantum dots (QDs) can act as the coreactant of Ru(bpy)(3)(2+) electrogenerated chemiluminescence (ECL) in neutral condition. Strong anodic ECL signal was observed at ~1.10 V at CdSe QDs modified glassy carbon electrode (CdSe/GCE), which might be mainly attributed to the apparent electrocatalytic effect of QDs on the oxidation of Ru(bpy)(3)(2+). Ru(bpy)(3)(2+) can be intercalated into the loop of hairpin DNA through the electrostatic interaction to fabricate a probe. When the probe was bound to the CdSe QDs modified on the GCE, the intense ECL signal was obtained. The more Ru(bpy)(3)(2+) can be intercalated when DNA loop has larger diameter and the stronger ECL signal can be observed. The loop of hairpin DNA can be opened in the presence of target DNA to release the immobilized Ru(bpy)(3)(2+), which can result in the decrease of ECL signal. The decreased ECL signal varied linearly with the concentration of target DNA, which showed the ECL biosensor can be used in the sensitive detection of DNA. The proposed ECL biosensor showed an excellent performance with high specificity, wide linear range and low detection limit.