title: Amplified impedimetric aptasensor based on gold nanoparticles covalently bound graphene sheet for the picomolar detection of ochratoxin A.
abstract: 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 (Rct) by 7~ orders of magnitude compared with that of the free aptamer modified electrode. Such designed aptasensor showed a decreased response of Rct 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.
authors: Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China.
authors: Ling
authors: L
authors: Jiang
authors: Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China.
authors: Jing
authors: J
authors: Qian
authors: Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China.
authors: Xingwang
authors: X
authors: Yang
authors: Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China.
authors: Yuting
authors: Y
authors: Yan
authors: Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China.
authors: Qian
authors: Q
authors: Liu
authors: Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China.
authors: Kan
authors: K
authors: Wang
authors: Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China. Electronic address: wangkun@ujs.edu.cn.
authors: Kun
authors: K
authors: Wang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D004247:DNA / Q000737:chemistry; D055664:Electrochemical Techniques; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009793:Ochratoxins / Q000032:analysis*; D010087:Oxides / Q000737:chemistry; D013499:Surface Properties; D014920:Wine / Q000032:analysis
chemical_list: D052157:Aptamers, Nucleotide; D009793:Ochratoxins; D010087:Oxides; C025589:ochratoxin A; D006046:Gold; D006108:Graphite; D004247:DNA
keywords: Aptasensor; Gold nanoparticles covalently bound graphene; Impedimetric; Ochratoxin A; Signal amplification