Application of electromodulated fluorescence to the study of the dynamics of single-strand oligonucleotides at modified gold surfaces.

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TitleApplication of electromodulated fluorescence to the study of the dynamics of single-strand oligonucleotides at modified gold surfaces.
Publication TypeJournal Article
Year of Publication2002
AuthorsWang, L, Silin, VI, Gaigalas, AK, Xia, J, Gebeyehu, G
JournalJ Colloid Interface Sci
Volume248
Issue2
Pagination404-12
Date Published2002 Apr 15
ISSN0021-9797
KeywordsElectrochemistry, Electrodes, Fluoresceins, Gold, Oligonucleotides, Sensitivity and Specificity, Spectrometry, Fluorescence, Surface Properties
Abstract

Single-strand oligonucleotides with fluorescein labels were immobilized on modified gold electrodes and the surface fluorescence intensity was measured as a function of the potential applied to the electrode. The potential consisted of a constant and sinusoidal parts. The fluorescence was detected synchronously with the sinusoidal component of the potential. Large variation in the electromodulated fluorescence (EmF) was observed as a function of the constant component of the applied potential. In the potential range -0.2 to +0.2 V (vs Ag/AgCl) the EmF signal was quasi-reversible. A model for surface fluorescence was applied to the analysis of the EmF in this potential range. The model assumed that the adsorption-desorption process and quenching by the metal were the dominant mechanisms responsible for the observed EmF. For constant potential more negative than -0.5 V, the observed EmF response appeared to have a contribution from ssDNA in solution. This interpretation was suggested by comparison to EmF from solutions containing free fluorescein or labeled ssDNA. Large variation in the EmF response was observed for electrodes modified with amine and carboxyl groups. This suggests that electrostatic interactions play a dominant role.

DOI10.1006/jcis.2001.8191
Alternate JournalJ Colloid Interface Sci
PubMed ID16290545