Journal
ANALYTICA CHIMICA ACTA
Volume 806, Issue -, Pages 128-135Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.aca.2013.11.003
Keywords
Gold nanoparticles covalently bound graphene; Signal amplification; Impedimetric; Aptasensor; Ochratoxin A
Categories
Funding
- National Natural Science Foundation of China [21375050, 21175061]
- Natural Science Foundation of Jiangsu province [BK20130481]
- China Postdoctoral Science Foundation [2012M520998]
- Natural Science Foundation of Education Bureau of Jiangsu Province, China [340 10KJA470007]
- Key Laboratory of Modern Agriculture Equipment and Technology 341 [NZ201109]
- Jiangsu Planned Projects for Postdoctoral Research Funds [1301141C]
- Research Foundation of Jiangsu University [12JDG087]
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An amplified electrochemical impedimetric aptasensor for ochratoxin A (OTA) was developed with picomolar sensitivity. A facile route to fabricate gold nanoparticles covalently bound reduced graphene oxide (AuNPs-rGO) resulted in a large number of well-dispersed AuNPs on graphene sheets with tremendous binding sites for DNA, since the single rGO sheet and each AuNP can be loaded with hundreds of DNA strands. An aptasensor with sandwich model was fabricated which involved thiolated capture DNA immobilized on a gold electrode to capture the aptamer, then the sensing interface was incubated with OTA at a desired concentration, followed by AuNPs-rGO functionalized reporter DNA hybridized with the residual aptamers. By exploiting the AuNPs-rGO as an excellent signal amplified platform, a single hybridization event between aptamer and reporter DNA was translated into more than 10(7) redox events, leading to a substantial increase in charge-transfer resistance (R-ct) by 7 similar to orders of magnitude compared with that of the free aptamer modified electrode. Such designed aptasensor showed a decreased response of R-ct to the increase of OTA concentrations over a wide range of 1 pg mL(-1)-50 ng mL(-1) and could detect extremely low OTA concentration, namely, 0.3 pg mL(-1) or 0.74 pM, which was much lower than that of most other existed impedimetric aptasensors. The signal amplification platform presented here would provide a promising model for the aptamer-based detection with a direct impedimetric method. (C) 2013 Elsevier B.V. All rights reserved.
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