A simple, sensitive, and reliable method for the voltammetric determination of bisphenol A （BPA） by using carboxylic group functionalized single-walled carbon nanotubes （f-SWCNT）/carboxylic-functionalized poly（3,...A simple, sensitive, and reliable method for the voltammetric determination of bisphenol A （BPA） by using carboxylic group functionalized single-walled carbon nanotubes （f-SWCNT）/carboxylic-functionalized poly（3,4-ethylenedioxythiophene） （PC4） complex modified glassy carbon electrode （GCE） has been successfully developed. The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques. The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS （0.1 mol/L, pH 7.0）. The surface morphology of the 3D network of composite film is beneficial for the adsorption ofanalytes. Under the optimized conditions, the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L （R2 = 0.9989）, with a limit of detection of 0.032 μmol/L （SIN = 3）. The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property off-SWCNT and the extraordinary conductivity of PC4. Furthermore, the proposed modified electrode displays high stability and good reproducibility. The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.展开更多
A simple and highly sensitive analysis by electrochemical voltammetry has been developed for diagnosis of the most destructive crop disease in Thailand known as sugarcane white leaf (SCWL). Determination of the corres...A simple and highly sensitive analysis by electrochemical voltammetry has been developed for diagnosis of the most destructive crop disease in Thailand known as sugarcane white leaf (SCWL). Determination of the corresponding DNA interaction has been obtained from the voltammetric signals of electroactive redox methylene blue (MB) by means of cyclic and differential pulse voltammetry. In this study, a chitosan-modified glassy carbon electrode (GCE) was created by self-assembly to produce electrostatic platform for effective immobilization of the DNA. Fabrication of SCWL-DNA hybridization detection system was performed by immobilizing the ssDNA probe as a specific sensor onto chitosan-modified GCE. Hybridization of complementary DNA from the real samples could then be detected by its respective MB signal. This fabricated DNA probe sensor was shown to be capable for discriminative identification among the DNAs from SCWL plants, mosaic virus infected sugarcane and healthy sugarcane plants. Relationship between the specific hybridization signal and DNA target concentration was also observed under optimal condition. The detection limit of 4.709 ng/μl with the regression coefficient (R2) of 0.998 and overall RSD of 2.44% were obtained by response curve fit analysis. The actual SCWL-ssDNA immobilization and hybridizing event were subsequently confirmed by an observation under atomic force microscope. Thus these experiments demonstrate the first successful and effective DNA based voltammetric electrochemical determination for a verification of the specific pathogenic infection within plants from the real epidemic field.展开更多
Equations between the differential order and the maximum of the fractional-order differential for the specified peak signals are developed based on the variation of the maximum of the specified peak signals at differe...Equations between the differential order and the maximum of the fractional-order differential for the specified peak signals are developed based on the variation of the maximum of the specified peak signals at different orders. Also, equations between the differential order and the zero-crossing of the fractional-order differential of the specified peak signals are proposed according to the variation of the zero-crossing of the specified peak signals at different orders. Characteristic paramters of the Gaus- sian peak, Lorentzian peak, and Tsallis peak can be estimated using estimator I and estimator II which are obtained by the equations above. As a result, a new method is presented to resolve the overlapped peaks signal. Firstly, a fractional-order differential of the specified peak signals is obtained with the fractional-order differentiation filter. Then, characteristic paramters of the specified peak signals can be extracted using estimator I and estimator II. Finally, the Tsallis peak is used as a model to assign the overlapping peak signals correctly. Experimental results show that the proposed method is efficient and effective for the simulated overlapping peaks and detected overlapping voltammetric peak signals.展开更多
A new method called spline convolution (SC) for resolving overlapped peaks was proposed in this paper. The differential pulse voltammetric overlapped peaks of mixtures of Pb(II) and Tl(I) were investigated by this me...A new method called spline convolution (SC) for resolving overlapped peaks was proposed in this paper. The differential pulse voltammetric overlapped peaks of mixtures of Pb(II) and Tl(I) were investigated by this method, and satisfactory results were obtained. The results show excellent correlation between peak areas of the processed signals and the concentrations.展开更多
A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with...A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with multi-walled carbon nanotubes in the presence of sodium lauryl sulfate.The experimental results suggest that the phcniramine in anionic surfactant solution exhibits electrocatalytic effect resulting in a marked enhancement of the peak current response.Peak current response is linearly dependent on the concentration of pheniramine in the range 200-1500 μg/mL with correlation coefficient 0.9987.The limit of detection is 58.31 μg/m L.The modified electrode shows good sensitivity and repeatability.展开更多
A series of new macrocyclic dioxo 13 aneN 4 bearing various functional pendants, 2 methylfuran (LF), 2 methylthiophene (LT), 2 methylpyridine (LP), have been synthesized and characterized, where dioxo 13 aneN ...A series of new macrocyclic dioxo 13 aneN 4 bearing various functional pendants, 2 methylfuran (LF), 2 methylthiophene (LT), 2 methylpyridine (LP), have been synthesized and characterized, where dioxo 13 aneN 4 is 1,4,7,10 tetraazacyclotridecane 11,13 dione. The solution behaviours of the nickel(Ⅱ) complexes have been studied by Uv vis, cyclic voltammetric techniques. The red shifts were observed for the absorption band maxima of the electronic spectra from NiLR 1 to NiLR 2 (R=2 methylfuran, 2 methylthiophene, 2 methylpyridine). The value of E 1/2 of the NiLR 2 is less than NiLR 1 and both of them are lower than that of the nickel(Ⅱ) complex of the unsubstituted ligand, and these reasons are discussed.展开更多
The voltammetric behaviors of methylhesperidine (MH) were studied by means of linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. In the Brit ton-Robinson buffer solutions with pH values from 2....The voltammetric behaviors of methylhesperidine (MH) were studied by means of linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. In the Brit ton-Robinson buffer solutions with pH values from 2.05 to 6.37, MH could yield three reduction waves PC1, PC2 and PC3. PC1 wave is an adsorptive pre-wave. PC2 wave is an irreversible reduc tion of pre-protonated MH involving one electron and one proton. PC3 wave is an irreversible wave of reduction species radical of MH involving one electron.展开更多
Combined with air annealing, rutile-structured IrO 2 nanoparticles with various sizes were prepared using colloidal method. The nanoparticles were used as the electrocatalysts for the oxygen evolution reaction （OER）...Combined with air annealing, rutile-structured IrO 2 nanoparticles with various sizes were prepared using colloidal method. The nanoparticles were used as the electrocatalysts for the oxygen evolution reaction （OER） in acidic media, and their grain size effect was studied. The results show that with the increase in annealing temperature, the grain size of the catalyst increases, and the voltammetric charges （the electroactive areas） and apparent activity for the OER decrease. The relationship between the intrinsic activity and the annealing temperature exhibits a volcano-type curve and the catalyst annealed at 550 ℃ achieved the best result.展开更多
A greater part of water-solnble organic substances, accounting for 6070To of the total, could be adsorbedby soils, which included strongly and weekly reducing substances, positively and negatively charged substancesan...A greater part of water-solnble organic substances, accounting for 6070To of the total, could be adsorbedby soils, which included strongly and weekly reducing substances, positively and negatively charged substancesand substances containing amido. There existed a tendency of decrease in adsorption of the negativelycharged organic substances by the soil from South China to North China, with expression as Coulombianadsorption. A simultaneous reduction of iron and manganese appeared with clear voltammetric behavioursupon oxidation of water-soluble organic substances. Complexation of organic ligands with ferrons iron andmanganous manganese was proved by differential pulse voltammetric method, with disappearance of oxidationpeaks of ferrous iron and manganous manganese at 0.00 V and 0.35 V and occurrence of Fe`+-complex andMn￣2+ -complex at 0.75 V and 1.2 V respectively, whose peak potentials shifted backward.展开更多
Non-enzymatic electrochemical sensor was developed for estimation of low-level cholesterol.Polyindole/tungsten carbide(PIN/WC)nanocomposite was synthesized and used as an electroactive material to develop low-cost mod...Non-enzymatic electrochemical sensor was developed for estimation of low-level cholesterol.Polyindole/tungsten carbide(PIN/WC)nanocomposite was synthesized and used as an electroactive material to develop low-cost modified stainless steel plate electrode(SSPE).Surface morphology of developed electrode was characterized by scanning electron microscopy.Electrochemical behavior of cholesterol was investigated through electron impedance spectroscopy,potentiodynamic polarization and cyclic voltammetry in 1-M KOH electrolytic solution.The quantification of cholesterol was studied by square wave voltammetry and differential pulse voltammetry.The calibration plots between the cholesterol concentration and peak current were in linear relation with limit of detection of 1.23×10^(−6) mol L^(−1).The overall result reveals that developed PIN/WC/SSPE electrode has excellent performance for trace-level cholesterol estimation and can be further employed for cholesterol monitoring in blood serum samples.展开更多
An electrochemical assay was developed for β-D-galactosidase in coliform bacteria Escherichia coli (E. coli) using p-aminophenyl-β-D-galactopyranoside (PAPG) as substrate. The hydrolysis of PAPG by pure β-D-galact...An electrochemical assay was developed for β-D-galactosidase in coliform bacteria Escherichia coli (E. coli) using p-aminophenyl-β-D-galactopyranoside (PAPG) as substrate. The hydrolysis of PAPG by pure β-D-galactosidase was investigated based on the cyclic voltammetric (CV) behavior of p-aminophenyl (PAP). The results obtained using the pure enzyme showed that the addition of magnesium ion facilitated the enzyme-catalytic reaction. K m at the optimal magnesium ion concentration (5 mmol/L) was 0.90 mmol/L. The substrate was also used for coliformbacteria, where β-D-galactosidase in the bacteria cells was strongly induced by isopropyl-β-D-thiogalactopyranoside (IPTG). When the E. coli cell density exceeded 1.1×10 3 mL -1, the CV response was linearly related to the number of E. coli, the detection time was about one hour. This method can be developed into a portable biosensor for rapid assay of coliform bacteria.展开更多
Voltammetric behavior of sodium 7-methoxyl-4'-hydroxylisoflavone-3'-sulfonate (SMHS) in the aqueous solu-tion from pH 1 to 5 was studied by linear sweep voltammetry, cyclic voltammetry and normal pulse voltamm...Voltammetric behavior of sodium 7-methoxyl-4'-hydroxylisoflavone-3'-sulfonate (SMHS) in the aqueous solu-tion from pH 1 to 5 was studied by linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. Experimental results showed that in 0.2 molL-1 sodium citrate-hydrochloric acid buffer solution (pH=4.65), SMHS caused only one reduction wave at -1.34 V (vs. saturated calomel electrode, SCE), which was an irreversi-ble adsorptive wave of SMHS protonized involving one electron and one proton. The peak current of SMHS on lin-ear sweep voltammogram was proportional to its concentration in the range of 8.0×10-6—8.0×10-5 molL-1 (r=0.995), and the detection limit was 5.0×10-6 mol昄-1. The method was applied to determination of SMHS in syn-thetic samples. In addition, its scavenging effect on superoxide anion radical was studied by the auto-oxidation of pyrogallol in HCl-tris buffer solution (pH=8.2) in order to explain its peculiar biological effects. The experimental results proved that SMHS has antioxidant quality, and it is an efficient free radical scavenger of superoxide anion radical.展开更多
Organic photovoltaic （OPV） cells were fabricated via vacuum vapor deposition with {4-[2-（3-di-cyanomethylidene-5,5-dimethylcyclohexenyl）vinyl]phenyl}di（1-naphthyl）amine （DNP-2CN） as the electron donor, and ful...Organic photovoltaic （OPV） cells were fabricated via vacuum vapor deposition with {4-[2-（3-di-cyanomethylidene-5,5-dimethylcyclohexenyl）vinyl]phenyl}di（1-naphthyl）amine （DNP-2CN） as the electron donor, and fullerene （C60） as the electron acceptor. A thin film （10 nm） of tris（8-quinolinolato）aluminum （Alq3） was adopted as the buffer layer. A device based on this DNP-2CN exhibited an open circuit voltage （Voc） of 370 mV, a short-circuit current density （Jsc） of 0.61 mAocm 2, and a white-light power conversion efficiency （ η） of 0.09% （AM1.5, 75 mW.cm^- 2）.展开更多
The voltammetric behaviors of rare earth ions-amino acids were studied.The reduction potential of Eu^(3+) was shifted positively and the peak separation of the cathodic and anodic peaks in cyclic voltammogram de- crea...The voltammetric behaviors of rare earth ions-amino acids were studied.The reduction potential of Eu^(3+) was shifted positively and the peak separation of the cathodic and anodic peaks in cyclic voltammogram de- creased when a certain amino acid was added to Eu^(3+) solution.Experimental results showed that Eu^(3+) was re- duced by way of forming complexes with amino acids which were adsorbed on mercury electrode surface.When histidine and formaldehyde existed simultaneously in the solution containing Eu^(3+),a well-defined reversible catalytic prewave of Eu^(3+) was obtained.Meanwhile,the reduction current of formaldehyde increased greatly with the addition of histidine.The mechanism was studied.Several other rare earth ions and amino acids were also studied preliminarily.展开更多
A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aque...A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aqueous solution. The redox peaks observed in the two-electrode cyclic voltammogram (CV) are assigned to the intrinsic redox transitions among the Everitt's salt, PB, and Prussian yellow for the film itself, the redox process of the Au substrate and the redox process of small-quantity ferri-/ferrocyanide impurities entrapped in the PB film, as also supported by ultraviolet-visible (UV-Vis) spectroelectrochemical data. The profile of the two-electrode solid-state CV for the PB powder sand-wiched between two gold-coated indium-tin oxide (ITO) electrodes is similar to that for two PB-modified Au electrodes in aqueous solution, implying similar origins for the corresponding redox peaks. The two-channel EQCM method is expected to become a highly effective technique for the studies of the two-electrode electrochemical behaviors of many other species/materials.展开更多
A new voltammetric enzyme immunoassay system was investigated based on p-nitrophenyl phosphate (PNPP) as the substrate for alkaline phosphatase (ALP). PNPP is enzymatically hydrolyzed and the product p-nitrophenol (P...A new voltammetric enzyme immunoassay system was investigated based on p-nitrophenyl phosphate (PNPP) as the substrate for alkaline phosphatase (ALP). PNPP is enzymatically hydrolyzed and the product p-nitrophenol (PNP) is detected by differential pulse voltammetry (DPV), which can be oxidized at +1.02 V (vs. Ag/AgCl) on bare glass carbon electrode (GCE). The conditions for enzymatic reaction and electrochemical detection were studied. According to this method, ALP can be detected with a detection limit of 2.8102 mU/L and a linear range of 4.0102 ~ 1.0106 mU/L.展开更多
Electrochemical voltammetric method can;be used to monitor cell health state during its growth. Here we studied the effect of caffeic acid on leukemia cells U937 by the voltammetric behavior of the cells. The result s...Electrochemical voltammetric method can;be used to monitor cell health state during its growth. Here we studied the effect of caffeic acid on leukemia cells U937 by the voltammetric behavior of the cells. The result showed that this drug had a negative influence on cell health. which suggests that caffeic acid may be used in inhibition of tumor cells.展开更多
Electrochemistry of nitrate reductases (NR) incorporated into 2-aminoethanethiol self-assembled on the gold electrode and polyacrylamide cast on the pyrolytic graphite electrode was examined. NR on chemical modified ...Electrochemistry of nitrate reductases (NR) incorporated into 2-aminoethanethiol self-assembled on the gold electrode and polyacrylamide cast on the pyrolytic graphite electrode was examined. NR on chemical modified electrode showed electrochemical cyclic voltammetric responses in phosphate buffers.展开更多
In this paper,the voltammetric behaviours of Ag cylinder electrode in 1 mol/dm(3) KOH solution have been investigated in the presence of ultrasound irradiation. The results based on the CV, EIS and polarization measur...In this paper,the voltammetric behaviours of Ag cylinder electrode in 1 mol/dm(3) KOH solution have been investigated in the presence of ultrasound irradiation. The results based on the CV, EIS and polarization measurements showed that ultrasound could enhance the mass transport, inhibit the oxygen evolution and increase the exchange current.展开更多
基金the financial support ofthis work by the NSFC(Nos.51272096,51263010)Jiangxi Provincial Department of Education(Nos.GJJ10678,GJJ11590)+2 种基金Natural Science Foundation of Jiangxi Province(Nos.2010GZH0041,20114BAB203015)Jiangxi Science&Technology Normal University(No.KY2010ZY13)Jiangxi Provincial Innovation Fund of Postgraduates(No.YC2012-S123)
文摘A simple, sensitive, and reliable method for the voltammetric determination of bisphenol A （BPA） by using carboxylic group functionalized single-walled carbon nanotubes （f-SWCNT）/carboxylic-functionalized poly（3,4-ethylenedioxythiophene） （PC4） complex modified glassy carbon electrode （GCE） has been successfully developed. The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques. The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS （0.1 mol/L, pH 7.0）. The surface morphology of the 3D network of composite film is beneficial for the adsorption ofanalytes. Under the optimized conditions, the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L （R2 = 0.9989）, with a limit of detection of 0.032 μmol/L （SIN = 3）. The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property off-SWCNT and the extraordinary conductivity of PC4. Furthermore, the proposed modified electrode displays high stability and good reproducibility. The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.
文摘A simple and highly sensitive analysis by electrochemical voltammetry has been developed for diagnosis of the most destructive crop disease in Thailand known as sugarcane white leaf (SCWL). Determination of the corresponding DNA interaction has been obtained from the voltammetric signals of electroactive redox methylene blue (MB) by means of cyclic and differential pulse voltammetry. In this study, a chitosan-modified glassy carbon electrode (GCE) was created by self-assembly to produce electrostatic platform for effective immobilization of the DNA. Fabrication of SCWL-DNA hybridization detection system was performed by immobilizing the ssDNA probe as a specific sensor onto chitosan-modified GCE. Hybridization of complementary DNA from the real samples could then be detected by its respective MB signal. This fabricated DNA probe sensor was shown to be capable for discriminative identification among the DNAs from SCWL plants, mosaic virus infected sugarcane and healthy sugarcane plants. Relationship between the specific hybridization signal and DNA target concentration was also observed under optimal condition. The detection limit of 4.709 ng/μl with the regression coefficient (R2) of 0.998 and overall RSD of 2.44% were obtained by response curve fit analysis. The actual SCWL-ssDNA immobilization and hybridizing event were subsequently confirmed by an observation under atomic force microscope. Thus these experiments demonstrate the first successful and effective DNA based voltammetric electrochemical determination for a verification of the specific pathogenic infection within plants from the real epidemic field.
基金Supported by the Air Science Foundation of China (Grant No. 04D52032)
文摘Equations between the differential order and the maximum of the fractional-order differential for the specified peak signals are developed based on the variation of the maximum of the specified peak signals at different orders. Also, equations between the differential order and the zero-crossing of the fractional-order differential of the specified peak signals are proposed according to the variation of the zero-crossing of the specified peak signals at different orders. Characteristic paramters of the Gaus- sian peak, Lorentzian peak, and Tsallis peak can be estimated using estimator I and estimator II which are obtained by the equations above. As a result, a new method is presented to resolve the overlapped peaks signal. Firstly, a fractional-order differential of the specified peak signals is obtained with the fractional-order differentiation filter. Then, characteristic paramters of the specified peak signals can be extracted using estimator I and estimator II. Finally, the Tsallis peak is used as a model to assign the overlapping peak signals correctly. Experimental results show that the proposed method is efficient and effective for the simulated overlapping peaks and detected overlapping voltammetric peak signals.
基金We thank the National Natural Science Foundation of China(Project No.29975033)the NSF of Guangdong Province(Project No.980340)for financial support.
文摘A new method called spline convolution (SC) for resolving overlapped peaks was proposed in this paper. The differential pulse voltammetric overlapped peaks of mixtures of Pb(II) and Tl(I) were investigated by this method, and satisfactory results were obtained. The results show excellent correlation between peak areas of the processed signals and the concentrations.
文摘A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with multi-walled carbon nanotubes in the presence of sodium lauryl sulfate.The experimental results suggest that the phcniramine in anionic surfactant solution exhibits electrocatalytic effect resulting in a marked enhancement of the peak current response.Peak current response is linearly dependent on the concentration of pheniramine in the range 200-1500 μg/mL with correlation coefficient 0.9987.The limit of detection is 58.31 μg/m L.The modified electrode shows good sensitivity and repeatability.
文摘A series of new macrocyclic dioxo 13 aneN 4 bearing various functional pendants, 2 methylfuran (LF), 2 methylthiophene (LT), 2 methylpyridine (LP), have been synthesized and characterized, where dioxo 13 aneN 4 is 1,4,7,10 tetraazacyclotridecane 11,13 dione. The solution behaviours of the nickel(Ⅱ) complexes have been studied by Uv vis, cyclic voltammetric techniques. The red shifts were observed for the absorption band maxima of the electronic spectra from NiLR 1 to NiLR 2 (R=2 methylfuran, 2 methylthiophene, 2 methylpyridine). The value of E 1/2 of the NiLR 2 is less than NiLR 1 and both of them are lower than that of the nickel(Ⅱ) complex of the unsubstituted ligand, and these reasons are discussed.
基金supported by the National Natural Science Foundation of China(Grant No.20275030)Key Item of Science and Technology by the Ministry of Education(Grant No.02187)the Special Foundation of the Educational Committee of Shaanxi Province(Grant No.01JK076).
文摘The voltammetric behaviors of methylhesperidine (MH) were studied by means of linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. In the Brit ton-Robinson buffer solutions with pH values from 2.05 to 6.37, MH could yield three reduction waves PC1, PC2 and PC3. PC1 wave is an adsorptive pre-wave. PC2 wave is an irreversible reduc tion of pre-protonated MH involving one electron and one proton. PC3 wave is an irreversible wave of reduction species radical of MH involving one electron.
基金Supported by the National Natural Science Foundation of China(21073137)National Basic Research Program of China(2012CB932800)
文摘Combined with air annealing, rutile-structured IrO 2 nanoparticles with various sizes were prepared using colloidal method. The nanoparticles were used as the electrocatalysts for the oxygen evolution reaction （OER） in acidic media, and their grain size effect was studied. The results show that with the increase in annealing temperature, the grain size of the catalyst increases, and the voltammetric charges （the electroactive areas） and apparent activity for the OER decrease. The relationship between the intrinsic activity and the annealing temperature exhibits a volcano-type curve and the catalyst annealed at 550 ℃ achieved the best result.
文摘A greater part of water-solnble organic substances, accounting for 6070To of the total, could be adsorbedby soils, which included strongly and weekly reducing substances, positively and negatively charged substancesand substances containing amido. There existed a tendency of decrease in adsorption of the negativelycharged organic substances by the soil from South China to North China, with expression as Coulombianadsorption. A simultaneous reduction of iron and manganese appeared with clear voltammetric behavioursupon oxidation of water-soluble organic substances. Complexation of organic ligands with ferrons iron andmanganous manganese was proved by differential pulse voltammetric method, with disappearance of oxidationpeaks of ferrous iron and manganous manganese at 0.00 V and 0.35 V and occurrence of Fe`+-complex andMn￣2+ -complex at 0.75 V and 1.2 V respectively, whose peak potentials shifted backward.
文摘Non-enzymatic electrochemical sensor was developed for estimation of low-level cholesterol.Polyindole/tungsten carbide(PIN/WC)nanocomposite was synthesized and used as an electroactive material to develop low-cost modified stainless steel plate electrode(SSPE).Surface morphology of developed electrode was characterized by scanning electron microscopy.Electrochemical behavior of cholesterol was investigated through electron impedance spectroscopy,potentiodynamic polarization and cyclic voltammetry in 1-M KOH electrolytic solution.The quantification of cholesterol was studied by square wave voltammetry and differential pulse voltammetry.The calibration plots between the cholesterol concentration and peak current were in linear relation with limit of detection of 1.23×10^(−6) mol L^(−1).The overall result reveals that developed PIN/WC/SSPE electrode has excellent performance for trace-level cholesterol estimation and can be further employed for cholesterol monitoring in blood serum samples.
文摘An electrochemical assay was developed for β-D-galactosidase in coliform bacteria Escherichia coli (E. coli) using p-aminophenyl-β-D-galactopyranoside (PAPG) as substrate. The hydrolysis of PAPG by pure β-D-galactosidase was investigated based on the cyclic voltammetric (CV) behavior of p-aminophenyl (PAP). The results obtained using the pure enzyme showed that the addition of magnesium ion facilitated the enzyme-catalytic reaction. K m at the optimal magnesium ion concentration (5 mmol/L) was 0.90 mmol/L. The substrate was also used for coliformbacteria, where β-D-galactosidase in the bacteria cells was strongly induced by isopropyl-β-D-thiogalactopyranoside (IPTG). When the E. coli cell density exceeded 1.1×10 3 mL -1, the CV response was linearly related to the number of E. coli, the detection time was about one hour. This method can be developed into a portable biosensor for rapid assay of coliform bacteria.
基金the National Natural Science Foundation of China (No. 20275030) the Key Item of Science and Technique by the Ministry of Education (No. 02187) the Foundation for University Key Teacher by the Ministry of Education (No. GG-150-71006-2
文摘Voltammetric behavior of sodium 7-methoxyl-4'-hydroxylisoflavone-3'-sulfonate (SMHS) in the aqueous solu-tion from pH 1 to 5 was studied by linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. Experimental results showed that in 0.2 molL-1 sodium citrate-hydrochloric acid buffer solution (pH=4.65), SMHS caused only one reduction wave at -1.34 V (vs. saturated calomel electrode, SCE), which was an irreversi-ble adsorptive wave of SMHS protonized involving one electron and one proton. The peak current of SMHS on lin-ear sweep voltammogram was proportional to its concentration in the range of 8.0×10-6—8.0×10-5 molL-1 (r=0.995), and the detection limit was 5.0×10-6 mol昄-1. The method was applied to determination of SMHS in syn-thetic samples. In addition, its scavenging effect on superoxide anion radical was studied by the auto-oxidation of pyrogallol in HCl-tris buffer solution (pH=8.2) in order to explain its peculiar biological effects. The experimental results proved that SMHS has antioxidant quality, and it is an efficient free radical scavenger of superoxide anion radical.
文摘Organic photovoltaic （OPV） cells were fabricated via vacuum vapor deposition with {4-[2-（3-di-cyanomethylidene-5,5-dimethylcyclohexenyl）vinyl]phenyl}di（1-naphthyl）amine （DNP-2CN） as the electron donor, and fullerene （C60） as the electron acceptor. A thin film （10 nm） of tris（8-quinolinolato）aluminum （Alq3） was adopted as the buffer layer. A device based on this DNP-2CN exhibited an open circuit voltage （Voc） of 370 mV, a short-circuit current density （Jsc） of 0.61 mAocm 2, and a white-light power conversion efficiency （ η） of 0.09% （AM1.5, 75 mW.cm^- 2）.
基金The project supported by the National Natural Science Foundation of China
文摘The voltammetric behaviors of rare earth ions-amino acids were studied.The reduction potential of Eu^(3+) was shifted positively and the peak separation of the cathodic and anodic peaks in cyclic voltammogram de- creased when a certain amino acid was added to Eu^(3+) solution.Experimental results showed that Eu^(3+) was re- duced by way of forming complexes with amino acids which were adsorbed on mercury electrode surface.When histidine and formaldehyde existed simultaneously in the solution containing Eu^(3+),a well-defined reversible catalytic prewave of Eu^(3+) was obtained.Meanwhile,the reduction current of formaldehyde increased greatly with the addition of histidine.The mechanism was studied.Several other rare earth ions and amino acids were also studied preliminarily.
基金the National Natural Science Foundation of China (Grant Nos. 20675029, 90713018 & 20335020)the Foundation of the Ministry of Education of China (jiaorensi[2000]26, jiaojisi[2000]65)+1 种基金Hunan Provincial Educational Department (05K009, 05A036)State Key Laboratory of Electroanalytical Chemistry
文摘A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aqueous solution. The redox peaks observed in the two-electrode cyclic voltammogram (CV) are assigned to the intrinsic redox transitions among the Everitt's salt, PB, and Prussian yellow for the film itself, the redox process of the Au substrate and the redox process of small-quantity ferri-/ferrocyanide impurities entrapped in the PB film, as also supported by ultraviolet-visible (UV-Vis) spectroelectrochemical data. The profile of the two-electrode solid-state CV for the PB powder sand-wiched between two gold-coated indium-tin oxide (ITO) electrodes is similar to that for two PB-modified Au electrodes in aqueous solution, implying similar origins for the corresponding redox peaks. The two-channel EQCM method is expected to become a highly effective technique for the studies of the two-electrode electrochemical behaviors of many other species/materials.
基金The work was supported by the National Natural Science Foundation of China(Grant No.20075013)the Natural Science Foundation of Shandong Province(Grant No.Y98B06025).
文摘A new voltammetric enzyme immunoassay system was investigated based on p-nitrophenyl phosphate (PNPP) as the substrate for alkaline phosphatase (ALP). PNPP is enzymatically hydrolyzed and the product p-nitrophenol (PNP) is detected by differential pulse voltammetry (DPV), which can be oxidized at +1.02 V (vs. Ag/AgCl) on bare glass carbon electrode (GCE). The conditions for enzymatic reaction and electrochemical detection were studied. According to this method, ALP can be detected with a detection limit of 2.8102 mU/L and a linear range of 4.0102 ~ 1.0106 mU/L.
文摘Electrochemical voltammetric method can;be used to monitor cell health state during its growth. Here we studied the effect of caffeic acid on leukemia cells U937 by the voltammetric behavior of the cells. The result showed that this drug had a negative influence on cell health. which suggests that caffeic acid may be used in inhibition of tumor cells.
基金We are grateful to the NNSFC (29973026), BNSF (2992007) Foundation for University Key Teacher by the Ministry of Education for the provision of financial support.
文摘Electrochemistry of nitrate reductases (NR) incorporated into 2-aminoethanethiol self-assembled on the gold electrode and polyacrylamide cast on the pyrolytic graphite electrode was examined. NR on chemical modified electrode showed electrochemical cyclic voltammetric responses in phosphate buffers.
文摘In this paper,the voltammetric behaviours of Ag cylinder electrode in 1 mol/dm(3) KOH solution have been investigated in the presence of ultrasound irradiation. The results based on the CV, EIS and polarization measurements showed that ultrasound could enhance the mass transport, inhibit the oxygen evolution and increase the exchange current.
