Electrochemiluminescence oxalic acid sensor having a platinum electrode coated with chitosan modified with a ruthenium (II) complex

Zhao, Changzhi; Egashira, Naoyoshi; Kurauchi, Yoshiaki; Ohga, Kazuya

doi:10.1016/s0013-4686(97)10007-x

Cited by 42 publications

(35 citation statements)

References 18 publications

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“…As a matter of fact, this type of charge effect on the redox chemistry between ruthenium polypyridyl complexes and reductants has been previously reported. For example, when Ru(bpy) 3 was immobilized in a positively-charged chitosan polymer matrix, its selectivity towards oxalate was enhanced relative to TPA as a result of the electrostatic attraction between the positive charges on the polymer and the oxalate anions [41].…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…2 Other reagents were of analytical grade or higher quality. Redistilled water was used throughout the work.…”

Section: Reagents and Apparatusmentioning

confidence: 99%

“…In previous studies, 2,3 we and others demonstrated that chitosan is a membrane material for a modified electrode, and is an excellent natural adsorbent for a negatively charged material with much higher selectivity. In a low-pH medium, chitosan on the surface of an electrode formed a net membrane protonated because the pKa of the parent chitosan is in the range of 5.5 -6.5 depending on the degree of protonation.…”

mentioning

confidence: 90%

Determination of EDTA Species inWater by Second-Derivative Square-Wave Voltammetry Usinga Chitosan-Coated Glassy Carbon Electrode

Zhao

Pan

et al. 2003

ANAL. SCI.

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“…6 Tetramethoxysilane (TMOS) was purchased from Shin-etsu Chem. Co. All other chemicals were of reagent grade or better and used without further purification.…”

Section: Materials and Apparatusmentioning

confidence: 99%

“…5 We have prepared an ECL-optic oxalic acid sensor having a Pt electrode coated with chitosan to which Ru(bpy) 3 2+ complex moieties are covalently bonded. 6 The oxalic acid sensor takes advantage of some characteristic properties of chitosan: the high content of a basic amino group, the high hydrophilicity and the ability to form a transparent thin film. The selectivity toward oxalic acid, however, is not very satisfactory for applications to practical samples.…”

mentioning

confidence: 99%

Electrochemiluminescence Sensor Having a Pt Electrode Coated with a Ru(bpy)32+-Modified Chitosan/Silica Gel Membrane

et al. 1998

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A sensor based on the electrochemiluminescence (ECL) of the Ru(bpy) 3 2+ complex is attractive in analytical chemistry because of its high substrate selectivity and high sensitivity. 1 -4 It is desired that the ECL sensor has a higher selectivity compared to ECL-based flow-through detectors for HPLC which have been reported by many reseachers. 5 We have prepared an ECL-optic oxalic acid sensor having a Pt electrode coated with chitosan to which Ru(bpy) 3 2+ complex moieties are covalently bonded. 6 The oxalic acid sensor takes advantage of some characteristic properties of chitosan: the high content of a basic amino group, the high hydrophilicity and the ability to form a transparent thin film. The selectivity toward oxalic acid, however, is not very satisfactory for applications to practical samples. The sol-gel method, on the other hand, gives a simple process which can be used to prepare gel materials that can immobilize different functional reagents in working electrodes. For example, Glezer and Lev 7 have prepared a glucose sensor having a Pt electrode coated with a vanadium pentaoxide matrix entrapping glucose oxidase. Dvorak and Armond 8 have reported a determination of Ru(bpy) 3 2+ by preconcentration into Pt and ITO electrodes coated with silica gel. Dominguez et al. 9 have studied the electrochemical behaviors of graphite electrodes coated with an ionexchange polymers/silica gel. We have recently prepared a Pt electrode coated doubly with Ru(bpy) 3 2+ -modified chitosan and silica-gel layers, which has been successfully applied to an ECL optic sensor with improved selectivity toward oxalic acid. 10 In the present paper we report on the fundamental behaviors, such as the potential dependence and the decay of the responses. Experimental Materials and apparatusRu(bpy) 3 2+ complex-modified chitosan was prepared from chitosan and bis(2,2¢-bipyridine)[4-methyl-4¢-(6-bromohexyl)-2,2¢-(bipyridine)]ruthenium(II) perchlorate.6 Tetramethoxysilane (TMOS) was purchased from Shin-etsu Chem. Co. All other chemicals were of reagent grade or better and used without further purification.Voltammetric experiments were performed using a system constructed by a Hokuto Denko HB 104 function generator, a Hokuto Denko HA 301 potentiostat and a Yokogawa 3086 X-Y recorder. The standard three-electrode arrangement consisted of a coated Pt disk (1.6 mmf), a Pt counter electrode and a Ag/AgCl reference electrode. A solution containing 0.1 M KNO 3 and 0.05 M phosphate buffer of pH 6.8 was used as the supporting electrolyte. Highly pure nitrogen was passed through an electrolytic cell thermostated at 25.0±0.2˚C prior to a measurement. ECL experiments were carried out using the same apparatus as reported previously 6,10 at room temperature; the potential applied to the photomultiplier was 900 V. The thickness of the membranes on the working electrode was determined by a Surfcom 575A surface texture measuring instrument (Tokyo Seimitsu Co., Japan). Preparation of sensor probeTMOS, water and methanol were mixed with a 2% ethanol solut...

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Electrochemiluminescence oxalic acid sensor having a platinum electrode coated with chitosan modified with a ruthenium (II) complex

Cited by 42 publications

References 18 publications

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

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

Determination of EDTA Species inWater by Second-Derivative Square-Wave Voltammetry Usinga Chitosan-Coated Glassy Carbon Electrode

Electrochemiluminescence Sensor Having a Pt Electrode Coated with a Ru(bpy)32+-Modified Chitosan/Silica Gel Membrane

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