Abstract
In the present paper, we report that CdSe quantum dots (QDs) can act as the coreactant of Ru(bpy)32+ 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)32+. Ru(bpy)32+ 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)32+ 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)32+, 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.
Highlights
Electrogenerated chemiluminescence (ECL) is a light emission that arises from the high-energy electron-transfer reaction between electrogenerated species
Previous work revealed that quantum dots (QDs) had good catalytic properties besides their good luminescent properties, which had rarely been studied in ECL43
Ru(bpy)32+ electrogenerated chemiluminescence (ECL) was studied at the CdSe/GCE in the absence of TPA to explore the possibility of QDs as the coreactant
Summary
Electrogenerated chemiluminescence (ECL) is a light emission that arises from the high-energy electron-transfer reaction between electrogenerated species. ECL is attracting more attention due to its low cost, wide linear range, simple instrumentation, and high sensitivity[1] Since it was first observed in the early 1970s, the Ru(bpy)32+ ECL has been extensively studied and widely used in immunoassays and DNA probe assays[2,3,4,5,6,7,8,9]. Since the oxidization process of QDs is similar to that of TPA, it is reasonable to speculate that the QDs modified on the GCE might act as a coreactant to generate anodic ECL with Ru(bpy)33+, which can sufficiently avoid the drawback of the introduction of coreactant in the solution and can find new roles of QDs in ECL investigation. The decreased ECL signal is linearly with the concentration of target DNA, which can be used in the sensitive detection of DNA
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