Autori: A.M. Oliveira-Brett, A.M. Chiorcea Paquim, V.C. Diculescu and J.A.P. Piedade

Editorial: Medical Engineering & Physics, 2006.

Rezumat:

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.

Cuvinte cheie: Electrochemical DNA-biosensor; AFM; Nanoscale; Nanobioelectrochemistry; Surface films; Quercetin; Adriamycin