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1.
A novel molecularly imprinted electrochemical sensor was developed for the sensitive and selective determination of ampicillin (AMP). The sensor was prepared on a platinum electrode modified with multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs), and a thin film of molecularly imprinted polymers (MIPs). MWCNTs and AuNPs were introduced to enhance the sensor's electronic transmission and sensitivity. The molecularly imprinted polymer (MIP) was synthesized using AMP as the template molecule, methacrylic acid as functional monomer, and ethylene glycol maleic rosinate acrylate (EGMRA) as cross‐linker. The performance of the proposed imprinted sensor was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The results showed that the imprinted film displayed a fast and sensitive response to AMP. Under optimal conditions, response peak current had a linear relationship with the concentration of AMP in the range of 1.0 × 10?8 mol/L to 5.0 × 10?6 mol/L and a detection limit of 1.0 × 10?9 mol/L (S/N = 3). This imprinted sensor was used to detect AMP in food samples with recoveries of 91.4–105%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40613.  相似文献   

2.
The polypyrrole and polyaniline copolymer coating (PPy‐PAni) and PPy‐PAni doped with sodium molybdate copolymer coating ( ) were synthesized on stainless steel by cyclic voltammetry. The effect of molybdate on the passivation of stainless steel was investigated by linear sweep voltammetry in 0.2 mol L?1 of oxalic acid. The corrosion prevention performances of these copolymer coatings for stainless steel were investigated by linear sweep voltammetry, electrochemical impedance spectroscopy in 1 mol L?1 of sulfuric acid, and potentiodynamic polarization in 0.1 mol L?1 of hydrochloric acid. Copolymer coating doped with molybdate could accelerate the formation of the passive oxide film and have better corrosion prevention efficiencies than PPy‐PAni coating on stainless steel. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40602.  相似文献   

3.
In this study, a new probe based on immobilization of amino linked oligonucleotide (NH2‐linked DNA) on poly(glycidyl methacrylate‐co‐vinylferrocene)‐coated Pt electrode was fabricated for the electrochemical detection of PTEN gene from human prostate tissues. The experimental parameters such as DNA immobilization time, DNA concentration, and target concentration were optimized. The selectivity of the NH2‐linked DNA probe was assessed with mismatch (MM) and noncomplementary (NC) sequences. The applicability of the NH2‐linked DNA probe to the PCR amplified samples correspond to PTEN gene from prostate tissues was evaluated. The immobilization of DNA on the copolymer was confirmed by FTIR, AFM, CV and DPV analysis. The PCR products were also identified by using agarose gel electrophoresis. The prepared probe indicated a linear range (10–100 μg mL?1) with a detection limit (4.7 μg mL?1) and a good selectivity of the NH2‐linked DNA probe toward target DNA sequence. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40638.  相似文献   

4.
A one‐step electrode surface modification is proposed in which a disposable, screen‐printed carbon electrode is functionalized with carbonized, electrospun polyacrylonitrile (PAN)‐loaded graphene (G) nanoparticles to form a composite, CPAN5G‐4x. The electrochemical behavior of the CPAN5G‐4x electrode was examined by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy and X‐ray diffraction were used to characterize the surface morphology and physical properties of the carbonized composite nanofibers before and after modification. The modified electrode was found to be effective for the detection of dopamine (DA) using square‐wave voltammetry (SWV) in the presence of interfering substances such as ascorbic acid and uric acid. With the addition of sodium dodecyl sulfate (SDS) to an optimized solution of phosphate‐buffered saline (PBS) at a pH of 2, the fabricated electrode exhibited enhanced electrocatalytic activity toward the oxidation of DA relative to PBS without SDS at a pH of 7.4. The SWV current displayed a linear response to DA concentrations ranging from 0.5 to 100 μM, with a limit of detection of 70 nM (S/N = 3) and a sensitivity of 1.4258 μA μM?1 cm?2. Finally, the CPAN5G‐4x electrode was used to determine DA levels in human serum. The modified electrode can potentially be harnessed for further electrochemical biosensor applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40858.  相似文献   

5.
A new highly selective electrochemical sensor for the determination of l ‐tryptophan was proposed by modifying the surface of screen‐printed carbon electrodes (SPCEs). The surface of SPCE was firstly modified by electropolymerization of p‐phenylenediamine (PPD). The polymer film was then covalently linked with cysteamine capped cadmium sulfide quantum dots (Cys‐CdS QDs) by using glutaraldehyde (GA) as a cross‐linker resulted in an organic–inorganic hybrid composite film (QDs/GA/PPD/SPCE). The modified electrode was applied as a working electrode for detecting various amino acids. It was found that the modified electrode gave an electrochemical response selectively to l ‐tryptophan over other amino acids. The experimental parameters, including pH of solution, buffer types, electropolymerization cycles, scan rate, and accumulation time, were studied and optimized. The proposed sensor can be used to detect l ‐tryptophan with a low detection limit of 14.74 µmol L?1 with good precision and the relative standard deviation less than 3.7%. The modified electrode was used to detect l ‐tryptophan in beverage samples and gave satisfactory recoveries from 91.9 to 104.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40356.  相似文献   

6.
A facile and green approach is used to synthesize polydopamine (PDA) functionalized reduced graphene oxide (RGO) via the self‐polymerization of dopamine (DA) under alkaline conditions. The obtained reduced RGO/PDA composite facilitate Au precursor adsorption. Then Au nanoparticles are reduced and assemble onto the surface of RGO/PDA composite form reduced RGO/PDA/gold (RGO/PDA/Au) nanocatalysts. After that, a sensitive electrochemical sensor for baicalein is fabricated based on RGO/PDA/Au nanocatalysts. In this method, the hydroxyl units of PDA can form hydrogen bonding with the phenolic hydroxyl groups of baicalein, making baicalein easily adsorb on the modified electrode surface to enhance the electrochemical response. The electrochemical mechanism of baicalein on the RGO/PDA/Au nanocatalysts modified GCE is thoroughly investigated by cyclic voltammetry. The fabricated electrochemical sensor show good electrochemical activity for baicalein. The linear range of baicalein is 1 × 10?8 to 15 × 10?6 mol L?1 with the detection limit of 3.1 × 10?9 mol L?1. Furthermore, the proposed electrochemical sensor can be used to detect real sample. The results reveal that this method provides a new avenue for electrochemical investigation of baicalein in biochemical, pharmaceutical, and clinical research. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 46720.  相似文献   

7.
An electrochemical molecularly imprinted polymer (MIP) sensor for detecting the existence of epigallocatechin‐3‐gallate (EGCG) in tea and its products was successfully developed on the basis of a glassy carbon electrode modified with an electropolymerized nonconducting poly(o‐phenylenediamine) film. The properties of the electrode were characterized by cyclic voltammetry, differential pulse voltammetry, and infrared spectroscopy. The template molecules could be rapidly and thoroughly removed by methanol/acetic acid. The linear response range for EGCG was 5.0 × 10?7–1.0 × 10?4 mol/L, and the limit of detection was as low as 1.6 × 10?7 mol/L. The prepared MIP sensor could discriminate between EGCG and its analogs. In addition, satisfactory results were obtained in the detection of real tea samples. The results of our investigation indicate that the MIP sensor was useful for the determination of EGCG with excellent selectivity, high sensitivity, repeatability, and reproducibility. This MIP sensor provides the potential for monitoring the variation of EGCG content during the industrial processes and for predicting the quality of tea and its products. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

8.
An ionic liquid modified screen-printed graphite electrode (SPE) was used for direct electrochemistry of herring sperm double strand DNA (dsDNA) by voltammetry. Due to the high conductivity of ionic liquid n-octylpyridinum hexafluorophosphate (OPPF), this electrode exhibited excellent electrochemical activity for the oxidation of dsDNA. Two irreversible oxidation peaks were obtained at the developed electrode, which corresponded to the oxidation of guanine and adenine residues present in the dsDNA. The basic electrochemical behavior of dsDNA at the OPPF modified SPE was carefully investigated. Combined with the differential pulse voltammetry, this electrode exhibited a good linear range from 20 μg mL−1 to 120 μg mL−1 with a detection limit of 5 μg mL−1 for the direct determination of dsDNA. Furthermore, the OPPF modified electrode displayed high reproducibility and stability for the dsDNA determination.  相似文献   

9.
A method for synthesizing Graphene oxide (GO)/nano‐sulfur/polypyrrole (PPy) ternary nanocomposite hydrogel is depicted. The higher surface area of GO, PPy porous structure and their excellent conductivity are utilized, and the GO hydrogel can be made easily. The products are characterized by field‐emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and electrochemical workstation. The results demonstrated that GO/nano‐S/PPy ternary nanocomposite hydrogel is successfully synthesized. The electrochemical properties are investigated by cyclic voltammetry, galvanostatic charge/discharge measurements, and cycling life in a three‐electrode system in 1M Li2SO4 electrolyte solution. The GO/nano‐S/PPy ternary nanocomposite hydrogel exhibit a high specific capacitance of 892.5 F g?1 at scan rates of 5 mV s?1 and the capacitance retain about 81.2% (594.8 F g?1) of initial capacitance (732.5 F g?1) after 500 cycles at a current density of 1 A g?1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40814.  相似文献   

10.
An electrochemical sensor based on Au nanoparticles (AuNPs)–poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (AuNPs–PDDA-G) nanocomposite was fabricated for the sensitive detection of alkannin. The nanocomposite was characterized by X-ray diffraction, ultraviolet/visible spectra, scanning electron microscopy, and transmission electron microscopy. Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behaviors of alkannin on the AuNPs–PDDA-G nanocomposite film-modified glassy carbon electrode. This electrochemical sensor displayed satisfactory analytical performance for alkannin detection over a range from 5.0 nmol L?1 to 3.0 μmol L?1 with a detection limit of 1.4 nmol L?1 (S/N = 3). Moreover, the sensor also exhibited good reproducibility and stability, and could be used for the detection of alkannin in real samples with satisfactory results.  相似文献   

11.
Polyaniline nano‐fibers with thorn surface morphology (T‐PANI) were synthesized by one‐step polymerization with adding additional aniline at later stage of chemical oxidation synthesis. In order to investigate the morphology role in determining electrochemical performance, the nano‐fibers PANI without thorn (PANI) was synthesized by the same polymerization process but at different time to add additional aniline. Material structures were characterized by field emission scanning electron microscope and Brunauer‐Emmett‐Teller method, and electrochemical performance was tested through cyclic voltammograms, galvanostatic charge‐discharge and electrochemical impedance spectroscopy. The data showed that the specific capacitance of T‐PANI was 443 F g?1 at 5 mA cm?2, which was much more than that of PANI (338 F g?1 at 5 mA cm?2). The solution resistance, charge transfer resistance, and diffuse resistance of T‐PANI were also lower than these of PANI. The results indicate that the thorn surface structure plays an important role in determining the electrochemical performance of polyaniline, which attribute to the improvements in pore size, pore distribution, special surface area, and conductivity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42266.  相似文献   

12.
BACKGROUND: A new electrochemical immunosensor for human chorionic gonadotropin (HCG) assay was developed based on Pt hollow nanospheres and silver/titanium dioxide nanocomposites. Silver nanoparticles were initially doped into TiO2 and chitosan (Cs) colloids to form silver/titanium dioxide nanocomposites (Ag? TiO2? Cs), which had good redox electrochemical activity and excellent film‐forming ability. Then, the free amino groups of chitosan were used to attach Pt hollow nanospheres for immobilization of human chorionic gonadotropin antibody (anti‐HCG) to construct an immunosensor. RESULTS: Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) confirmed consecutive growth of the multilayer films, and transmission electron microscopy (TEM) was used to describe the microstructure of nanoparticles. Optimal response of the immunosensor was obtained at pH 6.5 and 25 °C with an incubation time of 40 min. The immunosensor exhibited a linear range from 0.5 to 250 mIU mL?1 HCG with a detection limit of 0.26 mIU mL?1 at three times background noise. The selectivity, stability and repeatability of the immunosensor were satisfactory. CONCLUSION: The strategy showed low‐cost, high sensitivity, broad linear range and fast analytical time. It is expected that the immobilized technique and the detection methodology could be further developed for other proteins. Copyright © 2010 Society of Chemical Industry  相似文献   

13.
A conducting poly(azomethine)ester was prepared by solution phase polycondensation of a preformed Schiff base, 4‐((4‐(4‐(4‐hydroxybenzlideneamino) phenoxy)phenylimino)methyl)phenol and isophthaloyl chloride (I). Different aliphatic/aromatic moieties were incorporated for examining their effect on the electronic properties of material. The resulting polymers (10?4 to 25 S cm?1) were doped with silver (10?6 to 10?2 S cm?1) and blended with polyaniline (10?1 to 13.4 S cm?1) to enhance their electrical conductivity. Polymer/polyaniline blends had superior conductivity even at low polyaniline concentration relative to the silver‐doped chains. The data obtained experimentally were complemented by density function theory at the 6–31G/B3LYP level. The results showed that ΔE along with lowest unoccupied molecular orbital and highest occupied molecular orbital electron density accounts for the electrical properties. Spectroscopic (1HNMR, FTIR) and elemental analysis were used for structural elucidation. Structure–property relation in term of WXRD, SEM‐EDX, atomic force microscope, LLS, and thermal behavior was studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40698.  相似文献   

14.
Polyacrylamide‐b‐poly(methacrylic acid) was prepared on the surface of Au electrode (Au/PAM/PMAA) for Pb2+ ion electrochemical sensing via metal‐free visible‐light‐induced atom transfer radical polymerization, which was very simple, convenient, and environmentally friendly. Au/PAM/PMAA was carefully examined by cyclic voltammetry, electrochemical impedance spectroscopy, and X‐ray photoelectron spectroscopy. Further, Au/PAM/PMAA was successfully used for the determination of Pb2+ ion by differential pulse anodic stripping voltammetry. Under the optimal conditions, a linear response from 1.0 × 10?11 to 1.0 × 10?4 mol/L with detection limit of 2.5 × 10?12 mol/L (S/N = 3) was achieved from the results of experiments. Comparing with similar Pb2+ sensors, the broader linear range and lower detection limit suggested the promising prospect of Au/PAM/PMAA. In a word, the work of this article had an important significance for the polymer‐modified electrodes and the sensitive detection of Pb2+. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45863.  相似文献   

15.
In this work, an electrochemical β-nicotinamide adenine dinucleotide (NADH) sensor based on a carbon paste electrode modified with nickel oxide nanoparticles (NiONPs) was developed. The key highlights of this work are ease of preparation of the NiONPs-modified carbon paste electrode (NiONPs/MCPE), and its high sensitivity to NADH. The electrochemical characterization of NiONPs/MCPEs was performed via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical oxidation response of NADH was investigated by differential pulse voltammetry and chronoamperometry. The results indicated that the electrocatalytic effects of NiONPs on the response current of NADH significantly facilitated the electron transfer and improved the performance of the biosensor. Compared to bare carbon paste electrode (BCPE), the oxidation potential was shifted toward more negative potentials and the oxidation current was increased remarkably. Under optimum conditions, NADH could be detected in the range from 1.0 × 10?4 to 1.0 mmol L?1 with lower detection limit (0.05 μmol L?1). The proposed NADH sensor demonstrated fast and reproducible response. Furthermore, an ethanol biosensor was prepared using NiONPs and NAD+-dependent alcohol dehydrogenase enzyme giving linear responses over the concentration range of 1.6 and 38 mmol L?1 of ethanol.  相似文献   

16.
Thin film of a molecular imprinted polymer based on electropolymerization method with sensitive and selective binding sites for dimethoate was developed. This film was cast on gold electrode by electrochemical polymerization in solution of o-phenylenediamine and template dimethoate via cyclic voltammetry scans and further deposition of Ag nanoparticles. The surface plasmon resonance and cyclic voltammetric signals were also recorded simultaneously during the electropolymerization, controlling the thickness of the polymer film to be 25 nm. The imprinted film showed high selectivity towards to dimethoate. The recognition between the imprinted sensor and target molecule was observed by measuring the variation amperometric response of the oxidation–reduction probe, K3Fe(CN)6, on electrode. Under the optimal experimental conditions, the peak currents were proportional to the concentrations of dimethoate in two ranges, from 1.0 to 1000 ng mL?1 and from 1.0 to 50 μg mL?1, with the detection limit of 0.5 ng mL?1. Due to the high affinity, selectivity and stability the imprinted sensor provides a simple detection platform for organophosphate compounds.  相似文献   

17.

The work demonstrates the development of an electrochemical sensor for quantification of Chloramphenicol (CA) using pencil graphite electrode (PGE) modified with Gadolinium tungstate nano flakes and carbon nano fibers composite (PGE/GWNfs/CNFs). The composite was further characterized and confirmed by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, transmission electron microscopy analysis. The prepared GWNfs/CNFs nano composite was fabricated by drop casting method to get PGE/GWNfs/CNFs working electrode. The modified electrode is then analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) methods for its electrochemical and electrocatalytic property. The electrochemical investigation of developed sensor shows enhanced activity towards electro-oxidation of CA. The DPV studies revealed high efficacy characteristics such as sensitivity in the range 0.03984 µA µM?1 cm?2, selectivity, good linear range (5–50 μM), and low detection limit (0.4 μM). The study benchmarks the use of GWNfs/CNFs as an excellent transducer material in electrochemical sensing of CA in standard samples thus, it finds an efficient potential application in the analysis of CA in environment sample analysis.

  相似文献   

18.
Methylene blue (MB) redox mediator was introduced into polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend host to prepare a gel polymer electrolyte (PVA‐PVP‐H2SO4‐MB) for a quasi‐solid‐state supercapacitor. The electrochemical properties of the supercapacitor with the prepared gel polymer electrolyte were evaluated by cyclic voltammetry, galvanostatic charge–discharge, electrochemical impedance spectroscopy, and self‐discharge measurements. With the addition of MB mediator, the ionic conductivity of gel polymer electrolyte increased by 56% up to 36.3 mS·cm?1, and the series resistance reduced, because of the more efficient ionic conduction and higher charge transfer rate, respectively. The electrode specific capacitance of the supercapacitor with PVA‐PVP‐H2SO4‐MB electrolyte is 328 F·g?1, increasing by 164% compared to that of MB‐undoped system at the same current density of 1 A·g?1. Meanwhile, the energy density of the supercapacitor increases from 3.2 to 10.3 Wh·kg?1. The quasi‐solid‐state supercapacitor showed excellent cyclability over 2000 charge/discharge cycles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39784.  相似文献   

19.
Lithium‐sulfur battery is one of the most promising electrochemical energy storage systems because of its high theoretical specific capacity and energy density. When carbon materials are used for immobilizing sulfur, the technical challenge is designing their framework to relieve the shuttle effect of polysulfides intermediates and the volume change of sulfur, and to improve the conductivity of sulfur. Herein, polyaniline‐based carbon (PANI‐C) coated corn starch‐based activated carbon spheres (ACS@PANI‐C) was prepared and used as hosts of sulfur, which can effectively combine the advantages of physical entrapment and chemical binding interactions of sulfur species. The results of electrochemical performance test indicate that S/ACS@PANI‐C composites exhibit much better electrochemical performance than S/ACS composites. Its reversible capacities at 320, 480, 800 and 1600 mA g?1 are 687, 582, 504 and 393 mAh g?1, respectively. The improved electrochemical performance can be attributed to the PANI‐C which can also act as a flexible cushion to accommodate volume changes of sulfur cathode as well as a barrier to trap soluble polysulfide intermediates during the charge–discharge process. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46544.  相似文献   

20.
We report a new method for the synthesis of polythiophene (PTh)/graphene oxide (GO) nanocomposites by interfacial polymerization. Polymerization occurred at the interface of two immiscible solvents, i.e. n‐hexane containing thiophene and nitromethane containing GO and an initiator. Characterizations were done using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and electrochemical and electrical conductivity measurements. Spectroscopic analyses showed successful incorporation of GO in the PTh matrix. Morphological analysis revealed good dispersion of GO sheets in the polymer matrix. The PTh/GO composites showed marked improvements in thermal stability and electrical conductivity (2.7 × 10?4 S cm?1) compared to pure PTh. The composites exhibited excellent electrochemical reversibility compared to pure PTh at a scan rate of 0.1 V s?1. The composites were stable even up to 100 electrochemical cycles, indicating good cycle performance. The specific capacitance of the composites was calculated using cyclic voltammetry and was found to be 99 F g?1. © 2014 Society of Chemical Industry  相似文献   

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