Journal
MICROCHIMICA ACTA
Volume 180, Issue 1-2, Pages 101-108Publisher
SPRINGER WIEN
DOI: 10.1007/s00604-012-0900-8
Keywords
Chronocoulometric DNA biosensor; Dopamine; Gold nanoparticles; Multi-walled carbon nanotubes; Hexaammineruthenium (III) chloride
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Funding
- National Natural Science Foundation of China [20675002]
- Natural Science Foundation of Anhui Province [1208085QB33]
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We describe a sensitive chronocoulometric biosensor for the sequence-specific detection of DNA. It is based on a glassy carbon electrode modified with multi-walled carbon nanotubes, polydopamine, and gold nanoparticles. The ruthenium(III) hexammine complex acts as the electrochemical indicator. Electrochemical impedance spectra and scanning electron microscopy are employed to investigate the assembly of the electrode surface. The signals of the ruthenium complex electrostatically bound to the anionic phospho groups of the DNA strands are measured by chronocoulometry before and after hybridization. The difference in signal intensity is linearly related to the logarithm of the concentration of the target DNA in the range of 1.0 nM to 10 fM with a detection limit of 3.5fM (S/N=3) under optimal conditions. This biosensor exhibits excellent sensitivity and selectivity and has been used for an assay of complementary target DNA in human serum sample with satisfactory results.
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