Wanzhi Wei

Hunan University, Changsha, Hunan, China

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Publications (130)291.07 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper proposed a direct electrodeposition approach to synthesis of graphene-chitosan (GR-CS) composite onto glassy carbon electrode (GCE) under controlled potential. This direct electrodeposition approach for the construction of GR-based hybrid was environmentally friendly, which would not involve the chemical reduction of graphene oxide (GO) and therefore result in no further contamination. The whole procedure was simply and cost only several minutes. Moreover, Combining the advantages of GR (large surface-to-volume ratio and high conductivity) and CS (good biocompatibility and adsorption), the GR-CS composite could be highly efficient to capture OPs and used as solid phase extraction (SPE). The GR-CS/GCE was used to detect organophosphate pesticides (OPs), using methyl parathion (MP) as a model analyte. The significantly redox response of MP on the GR-CS/GCE was proved. The linear range was wide from 4.0 ng mL(-1) to 400 ng mL(-1), and a low detection limit of 0.8 ng mL(-1) for MP was achieved. Moreover, the proposed sensor exhibited high reproducibility, long-time storage stability and satisfactory anti-interference ability. The proposed GR-CS/GCE opens new opportunity for green, fast, simple, and sensitive analysis of OP compounds.
    Colloids and surfaces B: Biointerfaces 03/2012; 96:75-9. · 4.28 Impact Factor
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    ABSTRACT: The binding of dopamine (DA) with bovine serum albumin (BSA) was investigated for the first time by fluorescence and Fourier transform–infrared spectroscopy. The association constants, thermodynamic parameters, quenching rate constants at three different temperatures and the number of binding sites were also determined. The fluorescence results revealed that the fluorescence of BSA was quenched by DA through a static quenching procedure and a DA–BSA complex was formed. Synchronous fluorescence spectroscopy illustrated that DA interacted with both tyrosine residues and tryptophan residues of BSA. IR spectra revealed the structure changes of the BSA functional groups with the addition of DA. The thermodynamic study and IR spectra confirmed that hydrophobic and hydrogen bonds interactions were both the predominant intermolecular forces to stabilise the complex.
    Physics and Chemistry of Liquids - PHYS CHEM LIQ. 01/2012; 50(4):453-464.
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    ABSTRACT: A simple, sensitive, and reliable method based on a multi-walled carbon nanotubes (MWNTs) modified carbon ionic liquid electrode (CILE) has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The acid-treated MWNTs with carboxylic acid functional groups could promote the electron-transfer reaction of DA and inhibit the voltammetric response of AA. Due to the good performance of the ionic liquid, the electrochemical response of DA on the MWNTs/CILE was better than that of other MWNTs modified electrodes. Under the optimum conditions a linear calibration plot was obtained in the range 5.0×10(-8) to 2.0×10(-4) mol L(-1) and the detection limit was 1.0×10(-8) mol L(-1).
    Colloids and surfaces B: Biointerfaces 07/2011; 88(1):402-6. · 4.28 Impact Factor
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    ABSTRACT: Deoxyribonucleic acid (DNA) was electrochemically deposited on a carbon ionic liquid electrode to give a biosensor with excellent redox activity towards paraquat as shown by cyclic voltammetry and differential pulse voltammetry. Experimental conditions were optimized with respect to sensing paraquat by varying the electrochemical parameters, solution pH, and accumulation time of DNA. Under the optimized conditions, a linear relation exists between the reduction peak current and the concentration of paraquat in the range from 5 × 10−8 mol L−1 to 7 × 10−5 mol L−1, with a detection limit of 3.6 × 10−9 mol L−1. The utility of the method is illustrated by successful analysis of paraquat in spiked real water samples. FigureThe DNA was electrodeposited onto the CILE under +1.5V for 1200s. The electrochemical behaviors of paraquat on the modified electrode had been studied by cyclic voltammetry and differential pulse voltammetry. Five ml phosphate buffer (pH 7.0) solution was added into an electrochemical cell (10ml) and then paraquat was successfully added into the cell. The differential pulse voltammograms were recorded when swept from −0.8V to −0.3V. The peak currents at about −0.63V for paraquat were measured. KeywordsCarbon ionic liquid electrode–DNA–Differential pulse voltammetry–Electrochemistry deposition–Paraquat
    Microchimica Acta 07/2011; 174(1):89-95. · 3.43 Impact Factor
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    ABSTRACT: In this paper, we described a novel sensor based on tiron-doped polypyrrole and carbon nanotubes (CNTs) fabricated on low resistance monolayer-modified glassy carbon electrode. First, the dodecylamine monolayer was chemically modified. Second, CNTs were controllably adsorbed onto dodecylamine. Then, tiron doped polypyrrole was electro-deposited on the CNTs film. The layer-by-layer modified electrode was sensitive to dopamine, while it made no response to even high concentration of ascorbic acid. Parameters influencing the dopamine response were optimized. High performance of the sensor was obtained, such as wide concentration range, low detection limit (3 nM), low background current, high stability, and reproducibility.
    Analytical Letters 05/2011; 44(7):1226-1240. · 0.97 Impact Factor
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    ABSTRACT: A simple, sensitive, and reliable method based on a molecular sieve/ionic liquids composite electrode has been successfully developed for selective determination of dopamine (DA). The electrochemical behavior of dopamine (DA) at the modified electrode was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). The influence of experimental parameters including pH of solution, amount of modifier, accumulation potential and time on the response of DA was investigated. At the optimum conditions, the peak current of DA was linear with the concentration of DA in the wide range of 5.0 × 10−8 mol L−1 to 8 × 10−4 mol L−1, with the correlation coefficient of 0.9982. The detection limit was 1.0 × 10−8 mol L−1 (S/N = 3) in the presence of 0.2 mM ascorbic acid (AA). The interference studies showed that the modified electrode had excellent selectivity. What's more, the modified electrode also exhibited good reproducibility and stability for determination of DA, and could be applied to determine human serum samples.
    Electrochimica Acta. 01/2011; 56(6):2730-2734.
  • Yonghong Li, Xinsheng Liu, Wanzhi Wei
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    ABSTRACT: The electrochemical polymerization of glycine on carbon ionic liquid electrode (CILE) was described. The presence of ionic liquid on the surface of CILE facilitated the electropolymerization of glycine. The polyglycine modified CILE provided a valid and simple approach to selectively detect dopamine in the presence of AA in physiological environment. The proposed sensor not only decreased the voltammetric responses of AA but also dramatically enhanced the oxidation peak current of DA compared to bare CILE. Using square wave voltammetry, the modified CILE showed good electrochemical behavior to DA, a linear range of 1.0×10−7–3.0×10−4 M in the presence of 1 mM ascorbic acid (AA) and a detection limit of 5.0×10−9 M was estimated (S/N=3).
    Electroanalysis 01/2011; 23(12). · 2.82 Impact Factor
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    ABSTRACT: A new composite film comprising cationic gemini surfactant butane-α,ω-bis(dimethyl dodeculammonium bromide) (BDDA, C12-C4-C12) and poly (allylamine) hydrochloride(PAH) have been prepared. The composite film showed good biocompatibility and could promote the direct electron transfer between hemoglobin (Hb) and glassy carbon (GC) electrode. The immobilized Hb exhibited a pair of well-defined, quasi-reversible, and stable redox peaks with a formal potential of −0.158 V (vs. SCE) in 0.10 M pH 7 phosphate buffer solutions, and showed high affinity to hydrogen peroxide. The cathodic peak current of the electrode was linear with increasing concentration of H2O2 in the range of 5.14 to 200 μM.
    Analytical Letters 01/2011; 44(4). · 0.97 Impact Factor
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    ABSTRACT: An electrode was developed for the determination of hydrogen peroxide (H2O2). It contains a chitosan–copper complex onto which multi-wall carbon nanotubes in an ionic liquid were deposited. The modified electrode exhibited excellent electrocatalytic activity that was applied to the detection of H2O2. The pH value and the effect of electrical potential on the current response were optimized. The electrode displays good stability, an expanded linear response range, improved electrocatalytic activity towards H2O2, and enables detection of H2O2 with a linear response from 0.02 to 13 mM of H2O2, with a correlation coefficient of 0.997 and a response time of <6 s. The detection limit is 1.0 μM (at S/N = 3).
    Journal of Electroanalytical Chemistry. 01/2011; 655(1):92-95.
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    ABSTRACT: Heavy metal bioremediation by a multi-metal resistant endophytic bacteria L14 (EB L14) isolated from the cadmium hyperaccumulator Solanum nigrum L. was characterized for its potential application in metal treatment. 16S rDNA analysis revealed that this endophyte belonged to Bacillus sp. The hormesis of EB L14 were observed in presence of divalent heavy metals (Cu (II), Cd (II) and Pb (II)) at a relatively lower concentration (10mg/L). Such hormesis was the side effect of abnormal activities increases of ATPase which was planned to provide energy to help EB L14 reduce the toxicity of heavy metals by exporting the cations. Within 24h incubation, EB L14 could specifically uptake 75.78%, 80.48%, 21.25% of Cd (II), Pb (II) and Cu (II) under the initial concentration of 10mg/L. However, nearly no chromium uptake was observed. The mechanism study indicated that its remediation efficiencies may be greatly promoted through inhibiting the activities of ATPase. The excellent adaptation abilities and promising remediation efficiencies strongly indicated the superiority of this endophyte in heavy metal bioremediation at low concentrations, which could be useful for developing efficient metal removal system.
    Bioresource Technology 11/2010; 101(22):8599-605. · 5.04 Impact Factor
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    ABSTRACT: A colloidal gold-modified carbon ionic liquid electrode was constructed by mixing colloidal gold-modified graphite powder with a solid room temperature ionic liquid n-octyl-pyridinium hexafluorophosphate (OPPF(6)). Glucose oxidase (GOD) was entrapped in this composite matrix and maintained its bioactivity well and displayed excellent stability. The effect conditions of pH, applied potential and GOD loading were examined. Especially, the glucose oxidase entrapped in this carbon ionic liquid electrode fully retained its activity upon stressing in strongly acidic conditions (pH 2.0) for over one hour. The proposed biosensor responds to glucose linearly over concentration range of 5.0x10(-6) to 1.2x10(-3) and 2.6x10(-3) to 1.3x10(-2) M, and the detection limit is 3.5x10(-6) M. The response time of the biosensor is fast (within 10s), and the life time is over two months. The effects of electroactive interferents, such as ascorbic acid, uric acid, can be significantly reduced by a Nafion film casting on the surface of resulting biosensor.
    Biosensors & Bioelectronics 08/2010; 25(12):2675-9. · 6.45 Impact Factor
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    ABSTRACT: The direct electron transfer and electrocatalysis of hemoglobin (Hb) entrapped in the MCM-41 modified carbon ionic liquid electrode (CILE) were investigated by using cyclic voltammetry in 0.10 M pH 7.0 phosphate buffer solution (PBS). Due to its uniform pore structure, high surface areas and good biocompatibility, the mesoporous silica sieve MCM-41 provided a suitable matrix for immobilization of biomolecule. The MCM-41 modified CILE showed significant promotion to the direct electron transfer of Hb, which exhibited a pair of well defined and quasi-reversible peaks for heme Fe(III)/Fe(II) with a formal potential of -0.284 V (vs. Ag/AgCl). Additionally, the Hb immobilized on the MCM-41 modified carbon ionic liquid electrode showed excellent electrocatalytic activity toward H(2)O(2). The electrocatalytic current values were linear with increasing concentration of H(2)O(2) in a wide range of 5-310 microM and the corresponding detection limit was calculated to be 5 x 10(-8)M (S/N=3). The surface coverage of Hb immobilized on the MCM-41 modified carbon ionic liquid electrode was about 2.54 x 10(-9) molcm(-2). The Michaelis-Menten constant K(m)(app) of 214 microM indicated that the Hb immobilized on the modified electrode showed high affinity to H(2)O(2). The proposed electrode had high stability and good reproducibility due to the protection effect of MCM-41 and ionic liquid, and it would have wide potential applications in direct electrochemistry, biosensors and biocatalysis.
    Colloids and surfaces B: Biointerfaces 08/2010; 79(1):241-5. · 4.28 Impact Factor
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    ABSTRACT: An amperometric sensor for determination of nitrite was fabricated by electropolymerizing methylene blue (MB) on carbon nanotubes ionic liquid paste electrode (PMB/MWCNTs-CILE). The presence of MWCNTs in the carbon ionic liquid electrode could enhance the surface coverage amount of PMB and decrease the degradation of PMB, and promote the electron transfer rate. The proposed sensor showed electrocatalytic activity for the oxidation of nitrite in 0.1 M phosphate buffer solution (pH 4.0) and the oxidation peak occurred at low overpotential (0.768 V vs. Ag/AgCl). The effects of pH of the electrolyte, amount of MWCNTs, electropolymerization cycles and applied potential on the sensitivity of the sensor have been systemically investigated. The catalytic peak current was found to be linear with the nitrite concentration in the range of 0.5-67.9 μM, with a correlation coefficient of 0.9997, using amperometric measurements. The detection limit of 0.25 μM was obtained, with a sensitivity of 2.53 μA μM−1 cm−2. The sensor showed a fast response to nitrite (less than 5 s). The relative standard deviation (RSD) of the sensor response to 50 μM NaNO2 was 1.8% for eight replicate measurements and the sensor retained 94% of its initial response after it was kept in air for one month, indicated the sensor had good reproducibility and stability.
    Sensor Letters 07/2010; 8(4):584-590. · 0.52 Impact Factor
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    ABSTRACT: In this paper, DNA functionalized single-wall carbon nanotubes/Cu(2+) (DNA-CNTs/Cu(2+)) complex was one-step electrodeposited onto the glassy carbon electrode (GCE), which fabricated a DNA-CNTs/Cu(2+)/GCE sensor to detect nitrite. Cyclic voltammogram of DNA-CNTs/Cu(2+)/GCE showed a pair of well-defined redox peaks for Cu(2+)/Cu(+). Compared with DNA-CNTs/GCE and DNA-Cu(2+)/GCE, the prepared DNA-CNTs/Cu(2+)/GCE exhibited more excellent electrochemical properties. Thus, the prepared DNA-CNTs/Cu(2+)/GCE was proposed as nitrite sensor. The effects of Cu(2+), CNTs and DNA concentration in the mixture together with electrodeposition time and determination conditions such as applied potential, pH value on the current response of DNA-CNTs/Cu(2+)/GCE toward nitrite were optimized to obtain the maximal sensitivity. In addition, electrochemical experiments revealed that the modified electrode showed high electrocatalytic activity to the reduction of nitrite ion (NO(2)(-)). The linear range for the detection of NO(2)(-) was 3x10(-8) to 2.6x10(-3)M, and the response was very fast (less than 3s). A low detection limit of 3x10(-8)M (S/N=3) for NO(2)(-) was achieved.
    Analytica chimica acta 05/2010; 667(1-2):57-62. · 4.31 Impact Factor
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    ABSTRACT: In this paper, Cu nanoparticles/carbon nanotube/chitosan (Cunano/CNTs/CS) film was one-step electrodeposited onto the glassy carbon electrode (GCE), which fabricated a Cunano/CNTs/CS/GCE sensor to detect nitrite. One-step electrodeposition of CNTs and Cunano with the chitosan (CS) hydrogel was achieved, and the whole procedure takes only several minutes. Scanning electron microscopy (SEM) image demonstrated that the Cu nanoparticles coated on CNTs/CS were uniform, with an average size of 30 nm. The effects of Cu2+, CNTs and CS concentration in the mixture together with electrodeposition time and determination conditions such as applied potential, pH value on the current response of Cunano/CNTs/CS/GCE toward nitrite were optimized to obtain the maximal sensitivity. In addition, electrochemical experiments revealed that the modified electrode showed high electrocatalytic activity to the reduction of nitrite ion (NO2−). The linear range for the detection of NO2− was 1.0 × 10−7 M to 2.5 × 10−3 M with a high sensitivity of −48.92 μA mM−1, and the response was very fast (less than 2 s). A low detection limit of 2.4 × 10−8 M (S/N = 3) for NO2− was achieved.
    Sensors and Actuators B Chemical 03/2010; · 3.84 Impact Factor
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    ABSTRACT: Simultaneous determination of dihydroxybenzene isomers was investigated at a multi-wall carbon nanotubes (MWCNTs)/β-cyclodextrin composite modified carbon ionic liquid electrode in phosphate buffer solution (pH 7.0, 1/15 mol/L) in the presence of cationic surfactant cetylpyridinium bromide (CPB). With the great enhancement of surfactant CPB, the voltammetric responses of dihydroxybenzene isomers were more sensitive and selective. The oxidation peak potential of hydroquinone was about 0.024 V, catechol was about 0.140 V and resorcinol 0.520 V in differential pulse voltammetric (DPV) measurements, which indicated that the dihydroxybenzene isomers could be separated entirely. The electrode showed wide linear behaviors in the range of 1.2×10−7–2.2×10−3, 7.0×10−7–1.0×10−3, 2.6×10−6–9.0×10−4 mol/L for hydroquinone, catechol and resorcinol, respectively. And the detection limits of the three dihydroxybenzene isomers were 4.0×10−8, 8.0×10−8, 9.0×10−7 mol/L, respectively. The proposed method could be applied to the determination of dihydroxybenzene isomers in artificial wastewater, and the recovery was from 97.4% to 104.2%.
    Electroanalysis 03/2010; 22(9):1012 - 1018. · 2.82 Impact Factor
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    ABSTRACT: In this paper, Cu nanoparticles were electrodeposited onto the film of Nafion (Nf)-solubilized multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE), which fabricated a sensitive nano-copper coated multi-walled carbon nanotubes modified glassy carbon electrode (Cunano/CNTs–Nf/GCE) to detect nitrite. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) demonstrated that the Cu nanoparticles coated on MWCNTs were uniform, with an average size of 30nm. The effects of electrodeposition circles, CNTs–Nf solution concentration and determination conditions such as pH value and applied potential on the current response of Cunano/CNTs–Nf/GCE toward nitrite were optimized to obtain the maximal sensitivity. Moreover, electrochemical experiments revealed that the modified electrode sensor showed high electrocatalytic activity for the reduction of nitrite ion (NO2-). The linear range of the determination of NO2- was from 1.0×10−6M to 6.0×10−4M and the response was fast (less than 5s). A low detection limit of 8.0×10−8M (S/N=3) for NO2- was achieved.
    Journal of Electroanalytical Chemistry - J ELECTROANAL CHEM. 01/2010; 639(1):181-186.
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    ABSTRACT: A DNA-Ni2+ complex film was prepared by using direct electrodeposited method. The nickel ions immobilized in the DNA membrane exhibited an excellent and stable catalytic activity to the electro-oxidation of methanol. It was indicated that the DNA membrane would not block the methanol molecules diffuse into the catalytic active site in the membrane. Furthermore, it could make oxidation intermediate products which may poison the active site react sufficiently. As a result, the DNA membrane was an ideal carrier for the Ni ion immobilizing, and the utilization efficiency of catalysts Ni2+ could get higher.
    Catalysis Communications - CATAL COMMUN. 01/2010; 11(10):884-886.
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    ABSTRACT: The interaction between urea and guanidinium chloride (GuHCl) on lysozyme refolding was investigated in this work. Live micrococcus lysodeikticus was successfully introduced into a refolding system. Lysozyme can be refolded from the GuHCl-denatured, DTT-reduced state in a good yield of 96.54% at final protein concentration as high as 0.2 mg·mL-1. A model could be employed to elucidate refolding kinetics behavior and the kinetics constants were studied. In the coexistence of GuHCl and urea, the aggregation rate decreased by increasing urea concentration to a proper value. The cooperation of GuHCl and urea not only suppressed the competition of the aggregation reaction but also increased the yield of refolding efficiently.
    Analytical Letters 10/2009; 42(16):2625-2636. · 0.97 Impact Factor
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    ABSTRACT: A novel technology to obtain highly efficient biosorbent from the endophytes of a hyperaccumulator is reported. This technology is more convenient than the traditional method of obtaining biosorbents by experimentally screening many types of biomass by trial and error. Using this technology, endophytic fungus (EF) LSE10 was isolated from the cadmium hyperaccumulator Solanum nigrum L. It was identified as Microsphaeropsis sp. When cultured in vitro, the biomass yield of this EF was more than twice that of none-endophytic fungus (NEF) Rhizopus cohnii. Subsequently, it was used as a biosorbent for biosorption of cadmium from the aqueous solution. The results showed that the maximum biosorption capacity was 247.5mg/g (2.2 mmol/g) which was much higher than those of other adsorbents, including biosorbents and activated carbon. Carboxyl, amino, sulphonate and hydroxyl groups on EF LSE10 surface were responsible for the biosorption of cadmium.
    Bioresource Technology 10/2009; 101(6):1668-74. · 5.04 Impact Factor

Publication Stats

717 Citations
291.07 Total Impact Points

Institutions

  • 1991–2012
    • Hunan University
      • • College of Chemistry and Chemical Engineering
      • • Department of Chemical Engineering
      Changsha, Hunan, China
  • 2006
    • Jiujiang University
      Qianjin, Zhejiang Sheng, China
  • 1999
    • Changsha Railway University
      Ch’ang-sha-shih, Hunan, China