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Electrochemical DNAzyme Sensor for Lead Based on Amplification of DNA--Au Bio-Bar Codes.
- Source :
-
Analytical Chemistry . 8/15/2008, Vol. 80 Issue 16, p6323-6328. 6p. - Publication Year :
- 2008
-
Abstract
- An electrochemical DNAzyme sensor for sensitive and selective detection of lead ion (Pb2+) has been developed, taking advantage of catalytic reactions of a DNAzyme upon its binding to Pb2+ and the use of DNA-Au bio-bar codes to achieve signal enhancement. A specific DNAzyme for Pb2+ is immobilized onto an Au electrode surface via a thiol-Au interaction. The DNAzyme hybridizes to a specially designed complementary substrate strand that has an overhang, which in turn hybridizes to the DNA-Au biobar code (short oligonucleotides attached to 13 nm gold nanoparticles). A redox mediator, Ru(NH3)63+, which can bind to the anionic phosphate of DNA through electrostatic interactions, serves as the electrochemical signal transducer. Upon binding of Pb2+ to the DNAzyme, the DNAzyme catalyzes the hydrolytic cleavage of the substrate, resulting in the removal of the substrate strand along with the DNA bio-bar code and the bound Ru(NH3)63+ from the Au electrode surface. The release of Ru(NH3)63+ results in lower electrochemical signal of Ru(NH3)63+ confined on the electrode surface. Differential pulse voltammetry (DPV) signals of Ru(NH3)63+ provides quantitative measures of the concentrations of Pb2+, with a linear calibration ranging from 5 nM to 0.1 μM. Because each nanoparticle carries a large number of DNA strands that bind to the signal transducer molecule Ru(NH3)63+, the use of DNA-Au bio-bar codes enhances the detection sensitivity by five times, enabling the detection of Pb2+ at a very low level (1 nM). The DPV signal response of the DNAzyme sensor is negligible for other divalent metal ions, indicating that the sensor is highly selective for Pb2+. Although this DNAzyme sensor is demonstrated for the detection of Pb2+, it has the potential to serve as a general platform for design sensors for other small molecules and heavy metal ions. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00032700
- Volume :
- 80
- Issue :
- 16
- Database :
- Academic Search Index
- Journal :
- Analytical Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 34151722
- Full Text :
- https://doi.org/10.1021/ac800601y