Academic Journals Database
Disseminating quality controlled scientific knowledge

Immobilization of DNA at Glassy Ccarbon Electrodes: A Critical Study of Adsorbed Layer

ADD TO MY LIST
 
Author(s): M. L. Pedano | G. A. Rivas

Journal: Sensors
ISSN 1424-8220

Volume: 5;
Issue: 6;
Start page: 424;
Date: 2005;
Original page

Keywords: DNA-biosensors | DNA adsorption | glassy carbon electrode | DNA-modified electrode | redox indicator

ABSTRACT
In this work we present a critical study of the nucleic acid layer immobilized atglassy carbon electrodes. Different studies were performed in order to assess the nature of theinteraction between DNA and the electrode surface. The adsorption and electrooxidation of DNAdemonstrated to be highly dependent on the surface and nature of the glassy carbon electrode. TheDNA layer immobilized at a freshly polished glassy carbon electrode was very stable even afterapplying highly negative potentials. The electron transfer of potassium ferricyanide, catechol anddopamine at glassy carbon surfaces modified with thin (obtained by adsorption under controlledpotential conditions) and thick (obtained by casting the glassy carbon surface with highly concentratedDNA solutions) DNA layers was slower than that at the bare glassy carbon electrode, although thiseffect was dependent on the thickness of the layer and was not charge selective. Raman experimentsshowed an important decrease of the vibrational modes assigned to the nucleobases residues,suggesting a strong interaction of these residues with the electrode surface. The hybridization ofoligo(dG)21 and oligo(dC)21 was evaluated from the guanine oxidation signal and the reduction of theredox indicator Co(phen)33+ . In both cases the chronopotentiometric response indicated that thecompromise of the bases in the interaction of DNA with the electrode surface is too strong, preventingfurther hybridization. In summary, glassy carbon is a useful electrode material to detect DNA in adirect and very sensitive way, but not to be used for the preparation of biorecognition layers by directadsorption of the probe sequence on the electrode surface for detecting the hybridization event.
Save time & money - Smart Internet Solutions     

Tango Jona
Tangokurs Rapperswil-Jona