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An off–on–off electrochemiluminescence approach for ultrasensitive detection of thrombin

Author:
Deng, Li, Du, Ying, Xu, Jing-Juan, Chen, Hong-Yuan
Source:
Biosensors & bioelectronics 2014 v.59 pp. 58-63
ISSN:
0956-5663
Subject:
biosensors, complementary DNA, detection limit, electrochemiluminescence, energy transfer, glassy carbon electrode, nanocrystals, nanogold, oligonucleotides, surface plasmon resonance, thrombin
Abstract:
This work demonstrates an aptasensor for ultrasensitive electrochemiluminescence (ECL) detection of thrombin based on an “off–on–off” approach. The system is composed of an Eu3+-doped CdS nanocrystals (CdS:Eu NCs) film on glassy carbon electrode (GCE) as ECL emitter. Then gold nanoparticles (AuNPs) labeled hairpin-DNA probe (ssDNA1) containing thrombin-binding aptamer (TBA) sequence was linked on the NCs film, which led to ECL quenching (off) as a result of Förster-resonance energy transfer (FRET) between the CdS:Eu NC film and the proximal AuNPs. Upon the occurrence of hybridization with its complementary DNA (ssDNA2), an ECL enhancement (on) occurred owing to the interactions of the excited CdS:Eu NCs with ECL-induced surface plasmon resonance (SPR) in AuNPs at large separation. Thrombin could induce ssDNA1 forming a G-quadruplex and cause the AuNPs to be close to CdS:Eu NCs film again, which resulted in an enhanced ECL quenching (off). This “off–on–off” system showed a maximum 7.4-fold change of ECL intensity due to the configuration transformation of ssDNA1 and provides great sensitivity for detection of thrombin in a wide detection range from 50aM to 1pM.
Agid:
5533782