title: Impedance sensing of DNA binding drugs using gold substrates modified with gold nanoparticles.
abstract: Interfacial interactions between immobilized DNA probes and DNA-specific sequence binding drugs were investigated using impedance spectroscopy toward the development of a novel biosensing scheme. The impedance measurements are based on the charge-transfer kinetics of the [Fe(CN)6]3-/4- redox couple. Compared to bare gold surfaces, the immobilization of DNA and then the DNA-drug interaction on electrode surfaces altered the capacitance and the interfacial electron resistance and thus diminished the charge-transfer kinetics by reducing the active area of the electrode or by preventing the redox species from approaching the electrode. Electrochemical deposition of gold nanoparticles on a gold electrode surface showed significant improvement in sensitivity. DNA-capped gold nanoparticles on electrodes act as selective sensing interfaces with tunable sensitivity due to higher amounts of DNA probes and the concentric orientation of the DNA self-assembled monolayer. The specificity of the interactions of two classical minor groove binders, mythramycin, a G-C specific-DNA binding anticancer drug, netropsin, an A-T specific-DNA binding drug and an intercalator, nogalamycin on AT-rich DNA-modified substrate and GC-rich DNA-modified substrate are compared. Using gold nanoparticle-deposited substrates, impedance spectroscopy resulted in a 20-40-fold increase in the detection limit. Arrays of deposited gold nanoparticles on gold electrodes offered a convenient tool to subtly control probe immobilization to ensure suitably adsorbed DNA orientation and accessibility of other binding molecules.
authors.affiliation: Biotechnology Research Institute, National Research Council, Montreal, Quebec, H4P 2R2 Canada.
authors.forename: Chen-Zhong
authors.initials: CZ
authors.lastname: Li
authors.forename: Yali
authors.initials: Y
authors.lastname: Liu
authors.forename: John H T
authors.initials: JH
authors.lastname: Luong
mesh_terms: D004247:DNA / Q000737:chemistry*; D004347:Drug Interactions; D017097:Electric Impedance; D004563:Electrochemistry; D004566:Electrodes; D005292:Ferricyanides / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D012680:Sensitivity and Specificity
chemical_list: D005292:Ferricyanides; D007364:Intercalating Agents; D008024:Ligands; D006046:Gold; D004247:DNA