title: Low-background, highly sensitive DNA biosensor by using an electrically neutral cobalt(II) complex as the redox hybridization indicator.
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.
authors.affiliation: Fujian Province University Key Laboratory of Analytical Science, Department of Chemistry and Environment Science, Zhangzhou Normal University, Zhangzhou 363000, PR China. axiang236@126.com
authors.forename: Qingxiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Yingtao
authors.initials: Y
authors.lastname: Ding
authors.forename: Liheng
authors.initials: L
authors.lastname: Wang
authors.forename: Jiancong
authors.initials: J
authors.lastname: Ni
authors.forename: Zhanglong
authors.initials: Z
authors.lastname: Yu
authors.forename: Haibin
authors.initials: H
authors.lastname: Lin
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
mesh_terms: D015374:Biosensing Techniques; D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004247:DNA / Q000032:analysis*; D055664:Electrochemical Techniques; D004566:Electrodes; D007364:Intercalating Agents / Q000737:chemistry; D008968:Molecular Conformation; D009693:Nucleic Acid Hybridization; D010084:Oxidation-Reduction; D010618:Phenanthrolines / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D007364:Intercalating Agents; D010618:Phenanthrolines; D003035:Cobalt; D004247:DNA; C025205:1,10-phenanthroline