title: Fabricating a reversible and regenerable electrochemical biosensor for quantitative detection of antibody by using "triplex-stem" DNA molecular switch.
abstract: A reversible and regenerable electrochemical biosensor is fabricated for quantitative detection of antibody based on "triplex-stem" molecular switches. A hairpin-shaped oligonucleotide (hairpin DNA) labeled with ferrocene (Fc) at the 3'-end is fixed on the gold electrode serving as a signal transduction probe. Its hairpin structure leads Fc close to the surface of gold electrode and produces a strong current signal (on-state). A single-strand oligonucleotide modified with two digoxin molecules on the two arm segments (capture DNA) interact with hairpin DNA with the help of Ag(+) ions. The "triplex-stem" DNA forms, which separates Fc from the electrode and reduces the electrochemical signal (off-state). Binding of digoxin antibody to digoxin releases capture DNA from the hairpin DNA, creating an effective "off-on" current signal switch. The stability of the "triplex-stem" structure of hairpin/capture DNA is critical to the signal switch and the sensitivity of the method, which can be adjusted conveniently and efficiently by changing Ag(+) concentrations. Based on the "off-on" current signal switch, this biosensor is used to detect digoxin antibody sensitively in blood serum. The linear range is 1.0-500 pg with a correlation coefficient of 0.996, and the detection limit is 0.4 pg. Also, this biosensor shows excellent reversibility and reproducibility, which are significant requirements for practical biosensor applications.
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, Jiangsu, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, Jiangsu, PR China.
authors.forename: Linqun
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, Jiangsu, PR China.
authors.forename: Qiangwei
authors.initials: Q
authors.lastname: Ni
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, Jiangsu, PR China.
authors.forename: Yuepu
authors.initials: Y
authors.lastname: Pu
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, Jiangsu, PR China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Yin
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, Jiangsu, PR China. Electronic address: Liusq@seu.edu.cn.
authors.forename: Songqin
authors.initials: S
authors.lastname: Liu
mesh_terms: D000906:Antibodies / Q000032:analysis*; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry*; D004077:Digoxin / Q000097:blood*; D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006801:Humans
chemical_list: D000906:Antibodies; D004077:Digoxin; D006046:Gold; D004247:DNA
keywords: Antibody detection; DNA; Digoxin; Electrochemical biosensor; Molecular switch; Silver ion