title: Voltammetric behavior of DNA modified with osmium tetroxide 2,2'-bipyridine at mercury electrodes.
abstract: Osmium tetroxide complexes with nitrogen ligands (L) are probes of DNA structure and electroactive labels of DNA. Here adducts of single-stranded (ss) DNA with osmium tetroxide 2,2'-bipyridine (DNA-Os,bipy) were studied by cyclic voltammetry for the first time. It was found that at neutral pH DNA-Os,bipy produces three redox couples in the potential range between 0 and -1 V (peaks I-III) and a cathodic peak at about -1.3 V (peak IV). The latter peak decreased with increasing scan rate, and peaks arising from the forward and reverse scans exhibited the same direction, suggesting catalytic nature of the electrode process. We concluded that this peak corresponds to the known differential pulse voltammetric (polarographic) peak of DNA-Os,L adducts for which catalytic hydrogen evolution is responsible. In contrast, currents of cathodic peaks II and III increased almost linearly with increasing scan rate, suggesting involvement of adsorption in the electrode processes. Adsorptive stripping square-wave voltammetry was used to analyze the DNA-Os,bipy at low concentrations. It was shown that at neutral pH, peak III can offer sensitivity in the ppb range, which is only little lower than that reached by catalytic peak IV. The latter peak is, however, superior in sensitivity at acid pH values.
authors.affiliation: Institute of Biophysics, Academy of Sciences of Czech Republic, Královopolská 135,CZ-612 65, Brno, Czech Republic. raven@ibp.cz
authors.forename: Ludek
authors.initials: L
authors.lastname: Havran
authors.forename: Miroslav
authors.initials: M
authors.lastname: Fojta
authors.forename: Emil
authors.initials: E
authors.lastname: Palecek
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004247:DNA / Q000032:analysis* / Q000737:chemistry*; D015342:DNA Probes / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D008628:Mercury / Q000737:chemistry*; D009693:Nucleic Acid Hybridization / Q000379:methods; D009942:Organometallic Compounds / Q000032:analysis / Q000737:chemistry*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D020099:Coated Materials, Biocompatible; D015342:DNA Probes; D009942:Organometallic Compounds; D015082:2,2'-Dipyridyl; C076491:osmium tetroxide-2,2'-bipyridine; D004247:DNA; C427203:calf thymus DNA; D008628:Mercury