Electrochemical and DNA-binding properties of dipyridophenazine complexes of osmium(II)

Maruyama, Kenichi; Mishima, Yuji; Minagawa, Keiji; Motonaka, Junko

doi:10.1016/s0022-0728(01)00549-6

Cited by 43 publications

(27 citation statements)

References 30 publications

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“…Firstly, its oxidation potential is about 1.25 V vs. Ag=AgCl, and it is able to oxidize oxalate with high efficiency. Secondly, similar ruthenium and osmium complexes with dppz ligands have been shown in fluorescence and electrochemistry studies to intercalate into ds-DNA with relatively high affinity (K ¼ 10 6 -10 7 M À1 ) and selectivity [37][38][39][40]. Figure 5 illustrates the binding selectivity of Ru-dppz toward ds-DNA films assembled on an electrode surface.…”

Section: Resultsmentioning

confidence: 75%

Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

2006

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Abstract. DNA films immobilized on an indium tin oxide (ITO) electrode surface were detected and determined employing a high-affinity intercalator, Ru(bpy) 2 (dppz) 2þ (bpy ¼ 2,2 0 -bipyridine, dppz ¼ dipyrido[3,2-a:2 0 ,3 0 -c]phenazine), as a redox indicator, and oxalate as a sacrificial electron donor in solution to chemically amplify the voltammetric signal of the indicator. Nucleic acids were immobilized on ITO by layer-by-layer electrostatic adsorption, using avidin as the first layer and nucleic acid as the second layer. In quartz crystal microbalance (QCM) measurements on an avidin-coated gold surface, the amount of adsorption from a 200 mg mL À1 nucleic acid solution was found to be 3.2 ng mm À2 for both double-stranded (ds-) and single-stranded (ss-) calf-thymus DNA as well as polycytidylic acid (Poly-C). After binding with Ru(bpy) 2 (dppz) 2þ (Ru-dppz), voltammetry of the ds-DNA film on ITO was carried out in an indicator-free phosphate buffer. An anodic peak at about 1.15 V was observed, and it was assigned to Ru-dppz oxidation. When measured in an oxalate buffer, however, a catalytic current was observed due to the oxidation of oxalate by electrochemically generated Ru(bpy) 2 (dppz) 3þ , resulting in a 120-fold increase in the signal. Since oxalate itself produces a very low oxidation current on ITO, catalytic voltammetry produces about a 14-fold improvement in the signal-to-blank ratio over the nonamplified determination. As a result, ds-DNA adsorbed from 20 ng mL À1 solution could be detected, which was estimated by QCM to be 160 pg mm À2 on the surface. The catalytic current of ds-DNA was substantially higher than that of ss-DNA and poly-C, indicative of selective binding of the redox indicator to ds-DNA. The results serve as a basis for the catalytic voltammetric detection of DNA hybridization in future work.

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Section: Resultsmentioning

confidence: 75%

Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

2006

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“…One is that metal complexes with dppz ligand have the highest binding constant to date, with K = 10 6 -10 7 M À1 [29,34]. The other reason is that the formal potential of Ru(bpy) 2 dppz is as high as that of Ru(bpy) 3 .…”

Section: Resultsmentioning

confidence: 99%

“…Bard and colleagues [32,33] pioneered the field of electrochemical study of metal complex/DNA interaction, whereas Mikkelsen and others [9][10][11][12][13][14][15][16][17] used the redox-indicators in the detection of DNA hybridization events on electrode surfaces. The most promising indicators are the metal complexes containing the dipyrido[3,2-a :2 0 ,3 0 -c]phenazine (dppz) ligand, which have been found to intercalate into DNA with high affinity (K = 10 6 -10 7 M À1 ) due to its extended aromatic structure [29,34]. Not surprisingly, sensitive DNA assays have been reported using Ru-and Os-dppz complexes as either electrochemical or fluorescent probe [30,31,35].…”

Section: Introductionmentioning

confidence: 99%

A new chemically amplified electrochemical system for the detection of biological affinity reactions: direct and competitive biotin assay

Guo

Yang²

2005

Analyst

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A newly developed chemically amplified electrochemical detection system was applied to the quantitation of DNA in solution. The system employed Ru(bpy) 2 dppz (bpy = 2,2 0 -bipyridine, dppz = dipyrido[3,2-a :2 0 ,3 0 -c]phenazine), a high-affinity DNA intercalator, as the electrochemical indicator, oxalate as the sacrificial electron donor to chemically amplify the electrochemical signal, and tin-doped indium oxide as the working electrode to suppress background current. Intercalation of Ru(bpy) 2 dppz into calf thymus DNA in solution led to a reduction in the oxalate-amplified electrochemical current as compared to a DNA-free solution. The degree of reduction was a function of the concentration of DNA, thus forming the basis for DNA detection. To illustrate the advantages of the new system, a direct comparison was made between amplified (with oxalate) and non-amplified (without oxalate) DNA detection. In the presence of 100 mM oxalate, anodic current of Ru(bpy) 2 dppz was amplified by more than 60 folds, resulting in substantial improvement in signal-to-background ratio. Furthermore, as the DNA concentration was increased, the amplified current decayed much faster than the non-amplified signal, giving rise to higher detection sensitivity. The steeper decay was attributed to slower redox reaction between DNA-intercalated Ru(bpy) 2 dppz and oxalate, as the negatively charged phosphate groups on DNA repelled the anions. Effect of ionic strength was investigated to provide support for the interpretation. As expected, the decay of the amplified response with increasing concentration of DNA became less steep when more NaCl was added into the solution. The opposite effect was observed when tri-propylamine, a cationic electron donor, was used instead of oxalate. With an optimized concentration of 30 mM oxalate and 5 lM Ru(bpy) 2 dppz, calf thymus DNA of as low as 1 pM was detected in solution, which was close to the detection limit of some fluorescence measurements.

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“…Up to now, carbon materials including carbon paste, graphite, glassy carbon, carbon fiber, carbon nanotube and screen-printed electrodes been widely used for the nucleic acid research and electrochemical detection due to their several advantages such as easy handle, renewable, cheap, convenient and disposable in coming commercial uses . Various metals or metal oxides such as gold [77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96], platinum [97,98], silver [99][100][101] and indium tin oxide [102,103] etc have also been used in this filed.…”

Section: Electrode Materialsmentioning

confidence: 99%

DNA Electrochemical Behaviors, Recognition and Sensing by Combining with PCR Technique

2003

Sensors

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Abstract:The electrochemical studies on the behaviors and recognition of DNA have attracted considerable attention. DNA biosensors based on nucleic acid hybridization process are rapidly being developed towards the goal of rapid and inexpensive diagnosis of genetic and infectious diseases. This brief review focuses on the current state of the DNA electrochemical sensors with emphasis on recent advances, challenges and trends. The works on DNA electrochemical behaviors, recognition and detection in our group in the last three years are also introduced.

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Electrochemical and DNA-binding properties of dipyridophenazine complexes of osmium(II)

Cited by 43 publications

References 30 publications

Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

A new chemically amplified electrochemical system for the detection of biological affinity reactions: direct and competitive biotin assay

DNA Electrochemical Behaviors, Recognition and Sensing by Combining with PCR Technique

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