title: Electrochemistry of nanoscale DNA surface films on carbon.
abstract: A DNA electrochemical biosensor is an integrated receptor-transducer device. The most important step in the development and manufacture of a sensitive DNA-biosensor for the detection of DNA-drug interactions is the immobilization procedure of the nucleic acid probe on the transducer surface. Magnetic A/C Mode atomic force microscopy (MAC Mode AFM) images in air were used to characterize two different procedures for immobilising nanoscale double-stranded DNA (dsDNA) surface films on carbon electrodes. Thin film dsDNA layers presented holes in the dsDNA film that left parts of the electrode surface uncovered while thicker films showed a uniform and complete coverage of the electrode. These two procedures for preparing dsDNA-biosensors were used to study the influence of reactive oxygen species (ROS) in the mechanism of DNA damage by quercetin, a flavonoid, and adriamycin, an anthracycline anticancer drug. The study of quercetin-DNA interactions in the presence of Cu(II) ions indicated that the formation of a quercetin-Cu(II) complex leads to the formation of ROS necessary to react with DNA, disrupting the helix and causing the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo). Reduced adriamycin radicals are able to directly cause oxidative damage to DNA, generating 8-oxodGuo and ROS are not directly involved in this genomic mutagenic lesion.
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal. brett@ci.uc.pt
authors.forename: A M
authors.initials: AM
authors.lastname: Oliveira-Brett
authors.forename: A M Chiorcea
authors.initials: AM
authors.lastname: Paquim
authors.forename: V C
authors.initials: VC
authors.lastname: Diculescu
authors.forename: J A P
authors.initials: JA
authors.lastname: Piedade
mesh_terms: D000327:Adsorption; D015374:Biosensing Techniques / Q000379:methods*; D002244:Carbon / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004247:DNA / Q000032:analysis* / Q000737:chemistry* / Q000648:ultrastructure; D015342:DNA Probes / Q000032:analysis / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D008567:Membranes, Artificial; D010084:Oxidation-Reduction; D011794:Quercetin / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D015342:DNA Probes; D008567:Membranes, Artificial; D002244:Carbon; D004247:DNA; D011794:Quercetin