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Updated: May 11, 2026

A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis
Published on: September 10, 2014
Low-background, highly sensitive DNA biosensor by using an electrically neutral cobalt(II) complex as the redox
Qingxiang Wang1, Yingtao Ding, Liheng Wang
1Fujian Province University Key Laboratory of Analytical Science, Department of Chemistry and Environment Science, Zhangzhou Normal University, Zhangzhou 363000, PR China. axiang236@126.com
Abstract:
An electrically neutral cobalt complex, [Co(GA)2(phen)] (GA = glycollic acid, phen = 1,10-phenathroline), was synthesized and its interactions with double-stranded DNA (dsDNA) were studied by using electrochemical methods on a glassy carbon electrode (GCE). We found that [Co(GA)2(phen)] could intercalate into the DNA duplex through the planar phen ligand with a high binding constant of 6.2(±0.2)×10(5) M(-1). Surface studies showed that the cobalt complex could electrochemically accumulate within the modified dsDNA layer, rather than within the single-stranded DNA (ssDNA) layer. Based on this feature, the complex was applied as a redox-active hybridization indicator to detect 18-base oligonucleotides from the CaMV35S promoter gene. This biosensor presented a very low background signal during hybridization detection and could realize the detection over a wide kinetic range from 1.0×10(-14) M to 1.0×10(-8) M, with a low detection limit of 2.0 fM towards the target sequences. The hybridization selectivity experiments further revealed that the complementary sequence, the one-base-mismatched sequence, and the non-complementary sequence could be well-distinguished by the cobalt-complex-based biosensor.
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