title: Highly sensitive electrochemical impedance spectroscopic detection of DNA hybridization based on Au(nano)-CNT/PAN(nano) films.
abstract: A polyaniline nanofibers (PAN(nano))/carbon paste electrode (CPE) was prepared via dopping PAN(nano) in the carbon paste. The nanogold (Au(nano)) and carbon nanotubes (CNT) composite nanoparticles were bound on the surface of the PAN(nano)/CPE. The immobilization and hybridization of the DNA probe on the Au(nano)-CNT/PAN(nano) films were investigated with differential pulse voltammetry (DPV) and cyclic voltammetry (CV) using methylene blue (MB) as indicator, and electrochemical impedance spectroscopy (EIS) using [Fe(CN)(6)](3-/4-) as redox probe. The voltammetric peak currents of MB increased dramatically owing to the immobilization of the probe DNA on the Au(nano)-CNT/PAN(nano) films, and then decreased obviously owing to the hybridization of the DNA probe with the complementary single-stranded DNA (cDNA). The electron transfer resistance (R(et)) of the electrode surface increased after the immobilization of the probe DNA on the Au(nano)-CNT/PAN(nano) films and rose further after the hybridization of the probe DNA. The remarkable difference between the R(et) value at the DNA-immobilized electrode and that at the hybridized electrode could be used for the label-free EIS detection of the target DNA. The loading of the DNA probe on Au(nano)-CNT/PAN(nano) films was greatly enhanced and the sensitivity for the target DNA detection was markedly improved. The sequence-specific DNA of phosphinothricin acetyltransferase (PAT) gene and the polymerase chain reaction (PCR) amplification of nopaline synthase (NOS) gene from transgenically modified beans were determined with this label-free EIS DNA detection method. The dynamic range for detecting the PAT gene sequence was from 1.0 x 10(-12)mol/L to 1.0 x 10(-6)mol/L with a detection limit of 5.6 x 10(-13)mol/L.
authors.affiliation: Key Laboratory of Eco-chemical Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhou
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Chen
authors.initials: C
authors.lastname: Jiang
authors.forename: Meng
authors.initials: M
authors.lastname: Du
authors.forename: Kui
authors.initials: K
authors.lastname: Jiao
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D004247:DNA / Q000032:analysis* / Q000737:chemistry* / Q000235:genetics; D017097:Electric Impedance; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D009693:Nucleic Acid Hybridization / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000814:Aniline Compounds; C416807:polyaniline; D002244:Carbon; D006046:Gold; D004247:DNA; D019001:Nitric Oxide Synthase