title: Label-free DNA sensor by boron-doped diamond electrode using an ac impedimetric approach.
abstract: An electrochemical biosensor using a boron-doped diamond (BDD) electrode is described for differentiating between gene sequences according to DNA hybridization events using an ac impedimetric approach. BDD electrodes were dipped into a 1% solution of polyethylenimine (PEI) to adsorb a thin layer of positively charged PEI on the surface of BDD, then PEI-modified BDD electrodes were used to immobilize negatively charged single-stranded PCR fragments from Exon 7 of human p53 gene. Alternating current impedimetric measurements were first performed on these systems in phosphate buffered saline (PBS) and then upon exposure to single-stranded DNA (ssDNA). When the ssDNA-immobilized BDD electrode and solution ssDNA were completely complementary, a large drop in impedance was measured. Complementary DNA could be clearly detected at concentrations down to 10 (-19) g mL (-1) at a fixed frequency (10 Hz). Higher concentrations of DNA gave faster hybridization with saturation occurring at levels above 1.0 pg mL (-1.) Responses were much lower upon exposure to noncDNA, even at higher concentrations. The results show it is possible to directly detect target DNA at a fixed frequency and without additional labeling.
authors.affiliation: Research Center of Biomedical Engineering, College of Materials, Technology Research Center of Biomedical Engineering of Xiamen City, The Key Laboratory of Biomedical Engineering of Fujian Province, Xiamen University, PR China. jweng@xmu.edu.cn
authors.forename: Jian
authors.initials: J
authors.lastname: Weng
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Liping
authors.initials: L
authors.lastname: Sun
authors.forename: Chenghong
authors.initials: C
authors.lastname: Lin
authors.forename: Qiqing
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D001895:Boron / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D004247:DNA / Q000032:analysis* / Q000235:genetics; D004277:DNA, Single-Stranded / Q000378:metabolism; D018130:Diamond / Q000737:chemistry* / Q000378:metabolism; D017097:Electric Impedance; D004563:Electrochemistry; D004566:Electrodes; D016678:Genome / Q000235:genetics; D006801:Humans; D009693:Nucleic Acid Hybridization; D010957:Plasmids / Q000235:genetics; D011094:Polyethyleneimine / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D015203:Reproducibility of Results; D013194:Staining and Labeling; D013499:Surface Properties
chemical_list: D004277:DNA, Single-Stranded; D018130:Diamond; D011094:Polyethyleneimine; D004247:DNA; D001895:Boron