Journal
BIOSENSORS & BIOELECTRONICS
Volume 26, Issue 10, Pages 4236-4240Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2011.03.038
Keywords
Hemin/G-quadruplex; Horseradish peroxidase (HRP); Blocking reagent; Electrocatalytic; Aptasensor
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Funding
- Southwest China University [KB2010006]
- National Natural Science Foundation (NNSF) of China [21075100]
- Ministry of Education of China [708073]
- Natural Science Foundation of Chongqing City [CSTC-2009BA1003, CSTC-2010BB4121]
- State Key Laboratory of Electroanalytical Chemistry (SKLEAC [2010009]
- High Technology Project Foundation of Southwest University [XSGX02]
- Specialized Research Fund for the Doctoral Program of Higher Education [20100182110015]
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A simple electrochemical aptasensor for sensitive detection of thrombin was fabricated with G-quadruplex horseradish peroxidase-mimicking DNAzyme (hemin/G-quadruplex system) and blocking reagent-horseradish peroxidase as dual signal-amplification scheme. Gold nanoparticles (nano-Au) were firstly electrodeposited onto single wall nanotube (SWNT)-graphene modified electrode surface for the immobilization of electrochemical probe of nickel hexacyanoferrates nanoparticles (NiHCFNPs). Subsequently. another nano-Au layer was electrodeposited for further immobilization of thrombin aptamer (TBA), which later formed hemin/G-quadruplex system with hemin. Horseradish peroxidases (HRP) then served as blocking reagent to block possible remaining active sites and avoided the non-specific adsorption. In the presence of thrombin, the TBA binded to thrombin and the hemin released from the hemin/G-quadruplex electrocatalytic structure, increasing steric hindrance of the aptasensor and decomposing hemin/G-quadruplex electrocatalytic structure, which finally decreased the electrocatalytic efficiency of aptasensor toward H2O2 in the presence of NiHCFNPs with a decreased electrochemical signal. On the basis of the synergistic amplifying action, a detection limit as low as 2 pM for thrombin was obtained. (C) 2011 Elsevier B.V. All rights reserved.
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