Issue 12, 2013

Label-free electrochemiluminescent detection of DNA by hybridization with a molecular beacon to form hemin/G-quadruplex architecture for signal inhibition

Abstract

A facile label-free electrochemiluminescent (ECL) DNA sensor was designed using a molecular beacon with a guanine-rich stem as a recognition probe. The ECL emission was produced from surface unpassivated CdTe quantum dots (QDs) co-immobilized with colloidal gold nanoparticles (AuNPs) on a chitosan-modified electrode surface. The molecular beacon was adsorbed onto the AuNPs by the thiolated stem. Upon the hybridization of the molecular beacon with target DNA to open the cycle in the presence of hemin, the dissociated guanine-rich sequence could conjugate hemin to form a G-quadruplex architecture. The formed DNAzyme then catalyzed the reduction of dissolved oxygen, the endogenous coreactant for ECL emission of QDs, leading to a decrease in ECL signal. The variations in surface morphology during the fabrication and recognition processes of the ECL sensor were characterized by atomic force microscopy and electrochemical impedance spectroscopy. The ECL signal inhibition depended linearly on the logarithmic value of DNA concentration ranging from 5.0 fM to 0.1 nM, with a detection limit of 0.9 fM. This proposed label-free method is a promising application of QDs-based ECL emission for ultrasensitive DNA assay.

Graphical abstract: Label-free electrochemiluminescent detection of DNA by hybridization with a molecular beacon to form hemin/G-quadruplex architecture for signal inhibition

Article information

Article type
Paper
Submitted
04 Nov 2012
Accepted
05 Dec 2012
First published
10 Dec 2012

Nanoscale, 2013,5, 5435-5441

Label-free electrochemiluminescent detection of DNA by hybridization with a molecular beacon to form hemin/G-quadruplex architecture for signal inhibition

S. Deng, L. Cheng, J. Lei, Y. Cheng, Y. Huang and H. Ju, Nanoscale, 2013, 5, 5435 DOI: 10.1039/C2NR33471B

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