A label-free electrochemical biosensor for trace uranium based on DNAzymes and gold nanoparticles |
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| Authors: | Dandan Ma Yali Yuan Xilin Xiao Yangyang Gao Yuhui Li Wenhui Xu Wei Long |
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| Institution: | 1. School of Chemistry and Chemical Engineering, University of South China, Hengyang, 421001, Hunan, People’s Republic of China
2. University of South China, No. 28 changsheng Road, Hengyang, Hunan, China
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| Abstract: | A novel and highly sensitive electrochemical DNAzymes biosensor was fabricated using Au nanoparticles (AuNPs) immobilized on the surface of Au electrode that had been previously modified with self-assembled monolayers of 1,6-hexanedithiol. Different modified electrodes were prepared and characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The AuNPs were found to have a large surface area to anchor a large number of negatively charged phosphate backbones of DNAzymes, which further absorbed the electroactive indicator of hexaammineruthenium(III) (Ru(NH3)6]3+) to amplify the electrochemical signal. In the presence of target molecules, a large amount of DNA partly associated with Ru(NH3)6]3+ were removed from the electrode surface, leading to a significant decrease in peak current. Differential pulse voltammetry signals of Ru(NH3)6]3+ provided quantitative measures of the concentrations of uranyl ion (UO2 2+), with linear calibration ranging from 13 pM to 0.15 nM and a detection limit of 5 pM. The presence of other metal ions did not affect the detection of UO2 2+, which indicated the high specificity of UO2 2+. Therefore, a new electrochemical DNAzymes sensor was designed with specific DNAzymes and AuNPs as immobilization platform and signal amplifier. |
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