title: DNA sensor for o-dianisidine.
abstract: o-Dianisidine (3,3'-dimethoxybenzidine) is applied in the production of some dyes and also used in analytical tests. However, this compound is anticipated to be a human carcinogen. An analytical strategy utilizing square wave voltammetry for the determination of o-dianisidine is presented. An electrochemical system was consisted of three electrodes: carbon paste working electrode, platinum wire counter electrode and silver-silver chloride (Ag/AgCl) reference electrode. However, square wave voltammograms of direct measurements of o-dianisidine were found to be hardly reproducible, exhibiting few peaks due to some labile short-lived intermediates with the only exception of a quite stable peak at +0.7 V vs. Ag/AgCl. Quantitative determination of o-dianisidine gave satisfactory results only when the carbon paste working electrode was replaced by deoxyribonucleic acids (DNA) electrode obtained by immobilization of double-stranded (ds) DNA on carbon electrode. Square wave voltammogram of DNA showed two peaks attributed to adenine and guanine and the latter was used as analytical signal. After interaction with o-dianisidine, guanine oxidation peak was reduced to the extent related to the concentration of the analyte. Initial reduction of guanine peak took place already at the concentration of o-dianisidine equal to 0.4 microM; high concentrations (above 100 microM) of the analyte quenched completely a guanine response. The presented electrochemical system enables a specific detection of o-dianisidine by the presence of an oxidation peak at +0.7 V and its quantitative determination by measuring a reduction of guanine peak by means of a DNA sensor.
authors.affiliation: Chair of Biochemistry and Microbiology, Poznan University of Economics, 60-967, Poznan, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Jasnowska
authors.forename: M
authors.initials: M
authors.lastname: Ligaj
authors.forename: B
authors.initials: B
authors.lastname: Stupnicka
authors.forename: M
authors.initials: M
authors.lastname: Filipiak
mesh_terms: D000225:Adenine / Q000737:chemistry; D000818:Animals; D015374:Biosensing Techniques; D002138:Calibration; D002244:Carbon / Q000737:chemistry; D004396:Coloring Agents; D004247:DNA / Q000737:chemistry*; D003962:Dianisidine / Q000032:analysis*; D004563:Electrochemistry; D004566:Electrodes; D006147:Guanine / Q000737:chemistry; D006801:Humans; D010084:Oxidation-Reduction; D011199:Potentiometry; D012834:Silver / Q000737:chemistry; D018030:Silver Compounds / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D018030:Silver Compounds; D012834:Silver; D006147:Guanine; D002244:Carbon; D004247:DNA; D000225:Adenine; D003962:Dianisidine; C037548:silver chloride