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ABSTRACT: New graphene-silk peptide (Gr-SP) nanosheets were prepared and successfully fabricated with tyrosinase (Tyr) as a novel biosensor for the determination of phenolic compounds. The Gr-SP nanosheets were fully characterized with transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, UV/Vis and FTIR spectra. The developed biosensors were also characterized with scanning electronic microscopy and electrochemical impedance spectroscopy. Using bisphenol A (BPA) as a model substrate in the sensing system, a number of key factors including the volume of Gr-SP-Tyr solution, the applied potential, pH values, temperature, and the Tyr/Gr-SP ratio that influence the analytical performance of the biosensor were investigated. The biosensor gave a linear response on the concentration ranges of 0.001-16.91μM for catechol with the sensitivity of 7634mAM(-1)cm(-2), 0.0015-21.12μM for phenol with the sensitivity of 4082mAM(-1)cm(-2), and 0.002-5.48μM for BPA with the sensitivity of 2511mAM(-1)cm(-2). The low detection limits were estimated to be 0.23, 0.35 and 0.72nM (S/N=3) for catechol, phenol and BPA, respectively. The biosensors also exhibit good repeatability and long-term stability. The practical application of the biosensor was also demonstrated by the determination of BPA leaching from commercial plastic drinking bottles.
Biosensors & bioelectronics 01/2013; 44C:85-88. · 5.43 Impact Factor
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ABSTRACT: A novel nanocrystalline TiO2 (nano-TiO2) and Nafion composite film modified glassy carbon electrode has been developed for the determination of nitric oxide (NO)
radical in an aqueous solution. This modified electrode can be employed as a NO sensor with a low detection limit, fast response,
high sensitivity and selectivity. Two apparent anodic peaks were observed at 0.67 and 0.95V at the nano-TiO2 modified glassy carbon electrode by differential pulse voltammetry (DPV). After further modification with a thin film of
Nafion, which was capable of preventing some anionic interference such as nitrite and ascorbic acid, only one peak appeared
and the peak current enhanced greatly. The chronocoulometric experimental results showed NO was oxidized by one-electron transfer
reaction at the composite film modified electrode. The amperometric responses increased linearly with the concentrations of
NO ranging from 3.6×10−7mol/L to 5.4×10−5mol/L. The detection limit was estimated to be 5.4×10−8mol/L. In this sensor system, the modification film provides complete selectivity for NO over nitrite anions (NO2−).
Journal of Solid State Electrochemistry 04/2012; 10(6):383-388. · 2.13 Impact Factor
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ABSTRACT: A new electrode was developed by one-step potentiostatic electrodeposition (at −2.0 V for 20 s) of Au/SiO2 nanoparticles on a glassy carbon electrode. The resulting electrode (nano-Au/SiO2/GCE) was characterized by scanning electronic microscopy, X-ray photoelectron spectroscopy and electrochemical techniques. The electrochemical behavior of dihydronicotinamide adenine
dinucleotide (NADH) at the nano-Au/SiO2/GCE were thoroughly investigated. Compared to the unmodified electrode, the overpotential decreased by about 300mV, and
the current response significantly increased. These changes indicated that the modified electrode showed excellent catalytic
activity in the oxidation of NADH. A linear relationship was obtained in the NADH concentration range from 1.0 × 10−6 to 1.0 × 10−4mol L−1. In addition, amperometric sensing of ethanol at the nano-Au/SiO2/GCE in combination with alcohol dehydrogenase and nicotinamide adenine dinucleotide was successfully demonstrated. A wide
linear response was also found for ethanol in the range from 5.0 × 10−5 to 1.0 × 10−3mol L−1 and 1.0 × 10−3 to 1.0 × 10−2mol L−1, respectively. The method was successfully applied to determine ethanol in beer and biological samples.
KeywordsGold-Silicon dioxide-Nanoparticle-Electrodeposition-NADH-Ethanol
Microchimica Acta 04/2012; 171(3):399-405. · 3.03 Impact Factor
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ABSTRACT: Highly-ordered zirconium dioxide (ZrO(2)) nanotubes were prepared with porous anodic alumina as the template by the liquid phase deposition technique. The obtained ZrO(2) nanotubes were characterized by transmission electron micrograph (TEM) and X-ray diffraction (XRD). A new biocompatible nano-platform for the immobilization of hemoglobin (Hb) was developed by coating a chitosan (CHI) solution, in which the ZrO(2) nanotubes, 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid ([BMIM]BF(4)) and Hb were dispersed, onto a glassy carbon electrode surface. Direct electrochemistry of the immobilized Hb on the electrode surface was then investigated. The results indicated that remarkable improvements on the direct electrochemistry of Hb were achieved. In addition, the potential application of the Hb immobilized electrode (Hb/ZrO(2)/[BMIM]BF(4)/CHI/GCE) in biosensing was demonstrated by the catalytic electrochemical reduction of nitrite ion (NO(2)(-)) in an aqueous solution.
Bioelectrochemistry (Amsterdam, Netherlands) 04/2012; 84:6-10. · 2.65 Impact Factor
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ABSTRACT: Parathion imprinted polymer beads were prepared by free radical polymerization using parathion as template, methacrylic acid as functional monomer, divinyl benzene as cross-linking reagent and 2,2'-azobis(isobutyronitrile) as initiator. The obtained molecularly imprinted beads were characterized with transmission electron micrograph. The rebinding properties of these imprinted beads towards parathion were studied by saturation binding experiments using ultraviolet/visible spectroscopy. Effects of the template, functional monomer, cross-linking reagent and initiator on selective adsorption of parathion were investigated. The high selectivity of the imprinted beads was successfully demonstrated by their selective adsorption of free parathion from an ethanol-water (v/v=1:5) solution. In addition, the parathion imprinted beads were dispersed into dihexadecyl hydrogen phosphate solution at the concentration of 1.0 mg mL(-1). By coating this solution onto a glassy carbon electrode surface, a molecularly imprinted electrochemical sensor for parathion was obtained. The electrochemical sensor exhibited good selectivity and fast response to parathion. Under optimized experimental conditions, the peak currents were found linearly proportional to the parathion concentration in the range of 1.0×10(-7) mol L(-1) to 1.0×10(-5) mol L(-1) with a detection limit of 5.4×10(-8) mol L(-1) (S/N=3). The developed sensor was successfully employed for the determination of parathion in pear juice samples.
Colloids and surfaces. B, Biointerfaces 10/2011; 90:152-8. · 2.60 Impact Factor
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ABSTRACT: A gold/sodium dodecylbenzene sulfonate nanoparticles modified glassy carbon electrode (nano-Au/SDBS/GCE) was electrochemically fabricated with a constant potential at -0.4V. The obtained nano-Au/SDBS/GCE was characterized with scanning electronic microscopy, X-ray photoelectron spectroscopy and electrochemical techniques. Electrochemical behaviors of methyl parathion at the nano-Au/SDBS/GCE were thoroughly investigated. Compared to the unmodified electrode, the peak current obviously increased and the oxidation peak potential negatively shifted. These changes indicated that the composite nanoparticles possess good electrocatalytic performance on the electrochemical reaction of methyl parathion. Experimental parameters such as deposition time, pH value and accumulation conditions were optimized. Under optimum conditions, the peak current corresponding to the oxidation of the hydroxylamine group was found in a good linear relationship with the methyl parathion concentration. In addition, a calibration curve with excellent linearity was obtained in the concentration range from 5.0×10(-7)molL(-1) to 1.0×10(-4)molL(-1) with an estimated detection limit of 8.6×10(-8)molL(-1) (S/N=3). The successful determination of methyl parathion in real samples demonstrated the usefulness and potential applications of this method.
Colloids and surfaces. B, Biointerfaces 01/2011; 82(1):40-5. · 2.60 Impact Factor
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ABSTRACT: A methyl parathion-templated molecularly imprinted porous silicate thin film was electrodeposited onto a glassy carbon electrode using tetraethylorthosilicate sol as the silicon precursor and vinyltriethoxysilane as the functional monomer. The surface morphology and crystallinity of the imprinted film were characterized by scanning electron microscope and X-ray diffraction. The binding performance of the film with methyl parathion was examined with voltammetric techniques. The results show that the imprinted sol-gel film gives fast, sensitive and selective response to methyl parathion. The good selectivity of the film allows fine discriminations of methyl parathion from interferants, which including parathion, α-hydroxyl-4-nitrophenyl-dimethyl-phosphonate, p-nitrophenol and nitrobenzene. A linear range for methyl parathion determination was found from 1.0×10(-8) to 1.0×10(-5) mol l(-1) with an estimated detection limit of 8.9×10(-9) mol l(-1) (S/N=3). This imprinted sol-gel film electrode was proved to be a versatile sensing tool for the selective detection of methyl parathion in real samples.
Biosensors & bioelectronics 10/2010; 26(2):868-71. · 5.43 Impact Factor
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ABSTRACT: In this paper, a new electrochemical sensor, based on modified silver nanoparticles, was fabricated using one-step electrodeposition approach. The para-sulfonatocalix[6]arene-modified silver nanoparticles coated on glassy carbon electrode (pSC(6)-Ag NPs/GCE) was characterized by attenuated total reflection IR spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), etc. The pSC(6) as the host are highly efficient to capture organophosphates (OPs), which dramatically facilitates the enrichment of nitroaromatic OPs onto the electrochemical sensor surface. The combination of the host-guest supramolecular structure and the excellent electrochemical catalytic activities of the pSC(6)-Ag NPs/GCE provides a fast, simple, and sensitive electrochemical method for detecting nitroaromatic OPs. In this work, methyl parathion (MP) was used as a nitroaromatic OP model for testing the proposed sensor. In comparison with Ag NPs-modified electrode, the cathodic peak current of MP was amplified significantly. Differential pulse voltammetry was used for the simultaneous determination of MP. Under optimum conditions, the current increased linearly with the increasing concentration of MP in the range of 0.01-80microM, with a detection limit of 4.0nM (S/N=3). The fabrication reproducibility and stability of the sensor is better than that of enzyme-based electrodes. The possible underlying mechanism is discussed.
Talanta 05/2010; 81(3):1028-33. · 3.79 Impact Factor
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ABSTRACT: ZnS-polyacrylic acid (ZnS-PAA) was prepared by an in situ polymerization method using nano-ZnS as core in the presence of acrylic acid (AA), and ZnS-PAA nanoparticles was characterized by ultraviolet spectrometry (UV) and transmission electron microscopy (TEM). Based on the significant increase of the resonance light scattering (RLS) intensity with the interaction between nanoparticles and serum albumin, RLS method was developed for the sensitive determination of serum albumin (BSA and HSA). Under optimum conditions, the change of the intensity (DeltaI) of the RLS spectra at lambda=392nm was linearly proportional to the concentration of BSA and HSA. The linear range was 1-100ngmL(-1) for HSA and 1-120ngmL(-1) for BSA, and the limit of detection (LOD) was 0.4ngmL(-1) for HSA and 0.5ngmL(-1) for BSA. This method proved to be very sensitive, rapid, simple and tolerant of most interfering substances.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2010; 75(5):1497-500. · 2.10 Impact Factor
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ABSTRACT: A mesoporous zirconia modified carbon paste electrode was developed for electrochemical investigations of methyl parathion (MP, Phen-NO2). The significant increase of the peak currents and the improvement of the redox peak potential indicate that mesoporous zirconia facilitates the electronic transfer of MP. The oxidation peak current was proportional to the MP concentration in the range from 1.0×10−8 to 1.0×10−5 mol L−1 with a detection limit of 4.6×10−9 mol L−1 (S/N=3) after accumulation under open-circuit for 210 s. The proposed method was successfully applied to the determination of MP in apple samples.
Electroanalysis 12/2009; 22(2):151 - 154. · 2.87 Impact Factor
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ABSTRACT: Glassy carbon electrode modified with gold nanoparticles was prepared using electrodeposition at constant potential of -0.20V, and characterized with scanning electron microscopy and electrochemical techniques. Voltammetry was employed to study the electrochemical behaviors of tryptophan at the Au nanoparticles modified electrode in the presence of sodium dodecylbenzene sulfonate. The results showed that the Au nanoparticles modified electrode had good performance for the electrochemical oxidation of tryptophan. Compared with the unmodified electrode, the Au nanoparticles modified electrode improved the adsorption of tryptophan on the nanointerface and amplified its current response. The oxidation peak potential showed a negative shift of 50mV in the presence of sodium dodecylbenzene sulfonate indicating that the electron transfer between the electrode and bulk solution of tryptophan was facilitated. Experimental parameters for tryptophan determination, such as deposition time, pH value, and accumulation conditions have been optimized. The oxidation peak current was linearly dependent on the tryptophan concentration and a calibration curve was obtained in the concentration range of 9.0x10(-8)molL(-1) to 5.0x10(-5)molL(-1) with detection limit of 8.0x10(-8)molL(-1) (S/N=3).
Colloids and surfaces. B, Biointerfaces 11/2009; 76(1):340-5. · 2.60 Impact Factor
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ABSTRACT: A novel electrochemical sensor for methyl parathion based on silicate- cetyltrimethylammonium bromide nanocomposite film has been fabricated by electro-assisted deposition onto glassy carbon electrode in one-step via an electrochemical modulation of pH at the electrode/solution interface to promote controlled gelification of tetraethylorthosilicate sol, and was characterized with scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The electrochemical sensing of methyl parathion on the film-modified electrode was investigated applying cyclic voltammetry and square wave voltammetry. Compared to the unmodified electrode, the shapes of the redox peaks were improved and the peak currents significantly increased. Experimental parameters such as deposition time, pH value, and accumulation conditions have been optimized. A linear relationship between the peak current and methyl parathion concentration was obtained in the range from 1.0 x 10(-7) to 1.0 x 10(-4) mol L(-1) with a detection limit of 1.04 x 10 (-8) mol L(-1) (S/N = 3) after accumulation at 0 V for 120 s. The film electrode shows great promise for determination of methyl parathion in real samples.
Analytical and Bioanalytical Chemistry 10/2009; 396(2):697-705. · 3.78 Impact Factor
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ABSTRACT: Based on the enhancement of resonance light scattering (RLS) of serum albumin interaction with neutral red (NR) and sodium dodecyl sulfonate (SDS), a novel sensitive assay of serum albumins has been developed. Experimental conditions such as mixing sequence of reagents, pH, NR and SDS concentrations have been optimized. Linear relationships between the enhanced RLS intensity and the protein concentration were observed for bovine serum albumin (BSA) within the range of 0.01-5.0 microg mL(-1) and human serum albumin (HAS) of 0.01-7.0 microg mL(-1). The detection limits (S/N=3) are 6.0 ng mL(-1) for BSA and 5.0 ng mL(-1) for HAS, respectively. The method was successfully applied to the determination of HSA in human blood plasma samples with recovery from 97.3 to 104.3%.
Colloids and surfaces. B, Biointerfaces 02/2009; 71(1):84-7. · 2.60 Impact Factor
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Chunya Li
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ABSTRACT: Electrochemical behaviors of ethinylestradiol at a carbon paste electrode (CPE) in the presence of cetyl pyridine bromide (CPB) are investigated by electrochemical techniques. Compared with that at a CPE without CPB, the oxidation peak potential of ethinylestradiol shifts negatively and the peak current is increased significantly, due to the enhanced accumulation of ethinylestradiol via electrostatic interaction with CPB at the hydrophobic electrode surface. It is verified by the influences of different kinds of surfactants on the electrochemical signals of ethinylestradiol. Some parameters such as pH, scan rate, accumulation potential and accumulation time on the oxidation of ethinylestradiol are optimized. Under optimal conditions, the oxidation peak current is proportional to ethinylestradiol concentration in the range of 5.0 x 10(-8) to 2.0 x 10(-5) mol L(-1) with a detection limit of 3.0 x 10(-8) mol L(-1) for 150 s accumulation by linear sweep voltammetry (LSV). The proposed procedure is successfully applied to determine ethinylestradiol in pharmaceutical formulation (Levonorgestrel and Etinylestradiol tablets) and the results are satisfying compared with that of high-performance liquid chromatography (HPLC).
Bioelectrochemistry 06/2007; 70(2):263-8. · 3.76 Impact Factor
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ABSTRACT: An electrochemical sensor based on a molecularly imprinted TiO2 thin film is proposed for the determination of acetaminophen. The imprinted TiO2 films were obtained by liquid phase deposition (LPD) in the presence of acetaminophen, the functional monomer and the aqueous
solution of (NH4)2TiF6 and H3BO3. The results show that acetaminophen is embedded into the imprinted film in the presence of p-tert-butylcalix[6]arene as a functional monomer, and can be removed completely by washing with ethanol. The surface morphology,
spectral properties and electrochemical characterizations of the imprinted sensor were investigated in detail. The combination
of molecularly imprinted and LPD technique was shown to be a general strategy for constructing a molecular recognition system.
Microchimica Acta 04/2007; 158(3):307-313. · 3.03 Impact Factor
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Chunya Li
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ABSTRACT: Electrochemical behaviors of dipyridamole (DIP) at a carbon paste electrode in the presence of cetyltrimethyl ammonium bromide (CTAB) were investigated by voltammetry, chronocoulometry and electrochemical impedance spectroscopy (EIS). The results indicated that the electrochemical responses of DIP are apparently improved by CTAB, due to the enhanced accumulation of dipyridamole at the carbon paste electrode surface. Electrochemical parameters for the oxidation of DIP were explored by chronocoulometry. Under optimal conditions, the oxidation peak current at 0.53 V was proportional to DIP concentration in the range of 0.03-12 microg mL-1, with a detection limit of 0.01 microg mL-1 for 120 s accumulation by different pulse voltammetry (DPV). This method was applied to the determination of DIP in the tablet samples. The results were satisfying compared with that obtained by standardized method of high performance liquid chromatography (HPLC).
Colloids and Surfaces B Biointerfaces 04/2007; 55(1):77-83. · 3.46 Impact Factor
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Chunya Li
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ABSTRACT: 4-Nitrophenol (4-NP) has been determined with voltammetric technique based on a novel sensor fabricated by electropolymerization of carmine on a glassy carbon electrode (GCE). An obvious reduction peak located at about −0.700 V and a couple of redox peaks that were not well-defined were observed in the potential range of −1.00 to 0.600 V. Compared with its voltammetric behavior on a bare GCE, the reduction peak potential shifted positively and the peak current increased significantly. All experimental parameters were optimized and linear sweep voltammetry was proposed for its determination. In the optimal conditions, the reduction peak current was proportional to the 4-NP concentration over the concentration range from 5.00 × 10−8 to 1.00 × 10−5 mol L−1, and the detection limit was 1.00 × 10−8 mol L−1 after 200 s of accumulation. The high sensitivity and selectivity of the sensor was demonstrated by its practical application for the determination of trace amounts of 4-NP in lake water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3271–3277, 2007
Journal of Applied Polymer Science 03/2007; 103(5):3271 - 3277. · 1.29 Impact Factor
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ABSTRACT: A multi-wall carbon nanotube (MWNT)/cetyl pyridine bromine (CPB) composite film modified glassy carbon electrode (GCE) was
developed for the electrochemical determination of hymecromone in phosphonate buffer. Electrochemical behaviour of hymecromone
at the composite film electrode was investigated with voltammetry. Compared with an irreversible oxidation of hymecromone
at the bare GCE, the oxidation peak current was enhanced greatly at the film electrode. Some parameters such as pH, scan rate,
accumulation potential and accumulation time were optimized. Under optimal conditions, an oxidation peak at 0.82 V was employed
to determine hymecromone electrochemically. A linearity between the oxidation peak current and the hymecromone concentration
was obtained in the range of 3.0 × 10−7 − 2.0 × 10−5 mol 1−1 with a detection limit of 8.0 × 10−8 mol 1−1. The proposed procedure was successfully applied to assay hymecromone in pharmaceutical formulation with satisfactory results.
Russian Journal of Electrochemistry 01/2007; 43(12):1364-1368. · 0.53 Impact Factor
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ABSTRACT: A novel L-cysteine film modified electrode has been fabricated by means of an electrochemical oxidation procedure, and it
was successfully applied to the electrochemical determination of acetaminophen. This method utilizes the electrooxidation
of amines to their analogous cation radicals to form a chemically stable covalent linkage between the nitrogen atom of the
amine and edge plane sites at the glassy carbon electrode surface. The electrochemical behaviour of acetaminophen at the film
electrode was investigated in 0.1 mol L−1 phosphate buffer (pH 6.20). It was found that the redox peak current of acetaminophen was enhanced greatly on the film electrode.
Linearity between the oxidation peak current and the acetaminophen concentration was obtained in the range of 1.0 × 10−4–2.0 × 10−7 mol L−1 with a detection limit of 5.0 × 10−8 mol L−1. For seven parallel detections of 1.0 × 10−5 mol L−1 acetaminophen, the relative standard deviation (RSD) was 1.46%, suggesting that the film electrode has excellent reproducibility.
Application to the determination of acetaminophen in drug tablets and human urine demonstrated that the film electrode has
good stability and high sensitivity.
Microchimica Acta 09/2006; 155(3):365-371. · 3.03 Impact Factor
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Chunya Li
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ABSTRACT: A novel film electrode for the voltammetric determination of tyrosine has been constructed based on electropolymerization of L-serine on a glassy carbon electrode. Voltammetric behaviour of tyrosine on the poly-L-serine film electrode was investigated with cyclic voltammetry and linear sweep voltammetry, and electrochemical parameters were calculated from chronocoulometry. In optimal conditions, the oxidation peak current of tyrosine on the poly-L-serine film electrode was enhanced greatly. A sensitive oxidation peak at 0.90 V was employed to determine tyrosine. A linearity between the oxidation peak current and the tyrosine concentration was obtained in the range of 3.0 x 10(-7) to 1.0 x 10(-4) mol L(-1) with a detection limit of 1.0 x 10(-7)mol L(-1). The practical application of the film electrode in the determination of tyrosine in a commercial amino acid oral solution demonstrated that it has good selectivity and high sensitivity.
Colloids and Surfaces B Biointerfaces 08/2006; 50(2):147-51. · 3.46 Impact Factor
