Development and characterisation of a novel composite electrode material consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles

Composite material consisting of poly(3,4-ethylenedioxythiophene) (PEDOT), including Au nanoparticles encapsulated by N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulphonate (SB12) is synthesised by constant-current method on ITO glass, in aqueous medium, leading to an electrode coating. The synthesis process is followed by UV-vis spectroelectrochemistry, both in normal-beam and in parallel-beam configurations. Under the same experimental conditions PEDOT is also synthesised by electropolymerisation only in the presence of LiClO₄ supporting electrolyte, as well in solutions also containing SB12. The data relative to the electrosynthesis of the three materials are compared. The composite material based on the conductive polymer matrix including Au nanoparticles has been characterised by SEM, TEM, ICP, Raman and UV-vis spectroscopies. The behaviour of the three different electrode coatings with respect to p-doping process has been studied by conventional electrochemical techniques and by potentiostatic and potentiodynamic UV-vis spectroelectrochemical methods. Conclusions are drawn out about the effect of the presence of the surfactant and of Au nanoparticles on the electrochemical properties of the electrode system.     

Electrocatalytic oxidation of NADH on a glassy carbon electrode modified with MWCNT-Pd nanoparticles and poly 3,4-ethylenedioxypyrrole

An NADH biosensor based on MWCNTs-Pd nanoparticles and polymerized 3,4-ethylenedioxypyrrole (PEDOP) was developed and characterized. PEDOP/MWCNTs-Pd/GCE was prepared quickly and simply and showed improved sensitivity to NADH. Comparable results were obtained by cyclic voltammetric (CV) and amperometric methods for NADH determination. The amperometric method gave short response times, and linear regression was observed at concentrations below 1.0 mM. The proposed NADH biosensor exhibited a wide linear response range of 1 μM–13 mM during amperometric testing using an applied potential of 0.42 V, with a low detection limit of 0.18 μM (S/N = 3). The sensor demonstrated fast responses and good stability.     

Electrochemical characterization of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with sulfonated thiophenes

Sulfonated thiophenes, sodium 2-(3-thienyloxy)ethanesulfonate (C₆H₇S₂O₄Na) and sodium 6-(3-thienyloxy)hexanesulfonate (C₁₀H₁₅S₂O₄Na), were synthesized and used in the fabrication of ion-selective electrodes (ISEs) sensitive and selective to Ag⁺. The Ag⁺-ISEs were prepared by galvanostatic electropolymerization of 3,4-ethylenedioxythiophene (EDOT) on glassy carbon (GC) electrodes, with either C₆H₇S₂O₄⁻ or C₁₀H₁₅S₂O₄⁻ as the charge compensator (doping ion) for p-doped poly(3,4-ethylenedioxythiophene) (PEDOT). Potentiometric measurements were carried out with these sensors, GC/PEDOT(C₆H₇S₂O₄⁻) and GC/PEDOT(C₁₀H₁₅S₂O₄⁻), to study and compare their sensitivity and selectivity to silver ions. PEDOT(C₆H₇S₂O₄⁻) and PEDOT(C₁₀H₁₅S₂O₄⁻) films were also studied by using other techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), electrochemical quartz crystal microbalance (EQCM) and Fourier transform infrared spectroscopy (FTIR).Results from the potentiometric measurements showed that the difference in length of the alkyl chain of the doping ions C₆H₇S₂O₄⁻ and C₁₀H₁₅S₂O₄⁻ has no significant effect on the sensitivity or selectivity of GC/PEDOT(C₆H₇S₂O₄⁻) and GC/PEDOT(C₁₀H₁₅S₂O₄⁻) sensors to Ag⁺. More differences can be seen in the cyclic voltammograms and EIS spectra of the sensors. FTIR spectra confirmed that both C₆H₇S₂O₄⁻ and C₁₀H₁₅S₂O₄⁻ act as doping ions in the electrosynthesis of PEDOT-based films and they are not irreversibly immobilized in the polymer backbone.     

Electrochemical characterization of poly(eriochrome black T) modified glassy carbon electrode and its application to simultaneous determination of dopamine, ascorbic acid and uric acid

A polymerized film of eriochrome black T (EBT) was prepared on the surface of a glassy carbon (GC) electrode in alkaline solution by cyclic voltammetry (CV). The redox response of the poly(EBT) film at the GC electrode appeared in a couple of redox peak in 0.1 M hydrochloride and the pH dependent peak potential was −55.1 mV/pH which was close to the Nernst behavior. The poly(EBT) film-coated GC electrode exhibited excellent electrocatalytic activity towards the oxidations of dopamine (DA), ascorbic acid (AA) and uric acid (UA) in 0.05 mM phosphate buffer solution (pH 4.0) and lowered the overpotential for oxidation of DA. The polymer film modified GC electrode conspicuously enhanced the redox currents of DA, AA and UA, and could sensitively and separately determine DA at its low concentration (0.1 μM) in the presence of 4000 and 700 times higher concentrations of AA and UA, respectively. The separations of anodic peak potentials of DA-AA and UA-DA reached 210 mV and 170 mV, respectively, by cyclic voltammetry. Using differential pulse voltammetry, the calibration curves for DA, AA and UA were obtained over the range of 0.1-200 μM, 0.15-1 mM and 10-130 μM, respectively. With good selectivity and sensitivity, the present method provides a simple method for selective detection of DA, AA and UA in biological samples.     

Cathodically pretreated poly(1-aminoanthraquinone)-modified electrode for determination of ascorbic acid, dopamine, and uric acid

This paper describes a rapid and reliable method for dopamine (DA), ascorbic acid (AA), and uric acid (UA) determination in human urine using a cathodically pretreated poly(1-aminoanthraquinone) (PAAQ)-modified electrode. By applying a simple cathodic pretreatment to the PAAQ electrode well-defined voltammetric peaks for AA, DA, and UA were obtained. The pretreated PAAQ showed good selectivity, sensitivity, and repeatability for measuring AA, DA, and UA with detection limits of 2.50 × 10^?5, 3.05 × 10^?6, and 1.15 × 10^?5 M, respectively. The practical applicability of the modified electrode is illustrated by selective measurements of AA and UA in human urine without any preliminary treatment. Recovery values between 94.8 and 102 % for AA and between 77.8 and 100 % for UA were obtained with a relative standard deviation of 2.74 and 2.98 %, respectively.     

Electrochemical synthesis and characterization of novel electrochromic poly (3,4-ethylenedioxythiophene-co-Diclofenac) with surfactants

Copolymers prepared from 3,4-ethylenedioxythiophene (EDOT) and Diclofenac (DCF) through cyclic voltammetric method exhibited electroactive and electrochromic behaviours. Addition of DCF produced bathochromic shift of the EDOT main absorption band from 253.4 to 269.7 nm in the UV-vis spectra. The cyclic voltammetric studies were carried out with different feed concentration of DCF and in the presence of two different surfactants, SDS and CTAB on glassy carbon electrode surface. Effect of scan rate on the three types of electroactive copolymer films was studied. The three different copolymers showed good adherence on the glassy carbon electrode surface in aqueous 0.1 M KCl medium. Spectroelectrochemical analysis of copolymer film was carried out on Indium-Tin-Oxide (ITO) plate and it showed multicolor electrochromic behaviour when the applied potential was changed. The color of the copolymer was changed from neutral yellow to brown and to violet in 0.1 M KCl medium. Among the three different copolymers, the copolymer prepared in presence of CTAB resulted in high contrast colors. The electrochromic parameters such as coloration efficiency, optical contrast, response time and stability were also evaluated. The surface morphology of the copolymer films was characterized by SEM analysis.     

Determination of uric acid in the presence of ascorbic acid with hexacyanoferrate lanthanum film modified electrode

A glassy carbon electrode modified with LaHCF was constructed and was characterized by cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The resulting LaHCF modified glassy carbon electrode had a good catalytic character on uric acid (UA) and was used to detect uric acid and ascorbic acid (AA) simultaneously. This modified electrode exhibits potent and persistent electron-mediating behavior followed by well-separated oxidation peaks towards UA and AA with activation overpotential. For UA and AA in mixture, one can well separate from the other with a potential large enough to allow the determination of one in presence of the other. The DPV peak currents obtained increased linearly on the UA in the range of 2.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol/L with the detection limit (signal-to-noise ratio was 3) for UA 1.0 × 10⁻⁷ mol/L. The proposed method showed excellent selectivity and stability, and the determination of UA and AA simultaneously in urine was satisfactory.     

Different steps in the electrosynthesis of poly(3,4-ethylenedioxythiophene) on platinum

The initial stages of poly(3,4-ethylenedioxythiophene) (PEDOTh) film growth on platinum electrodes from TBAClO₄/acetonitrile solution are investigated by means of current-time transient measurements and tapping mode atomic force microscopy. It is shown that, for growth potentials in the range 1.17-1.29 V vs. SCE, the deposition process involves the formation of oligomers in the solution, progressive nucleation of centres of the new phase and three-dimensional growth of a first compact layer followed by a non-uniform distribution of granular-like clusters, whose number and size increase with the synthesis potential and charge. The obtained results reveal that PEDOTh films prepared at distinct potentials but with the same growth charge (Q_g) display similar electroactivities. They also depict that the electrochemical behaviour of the films is a function of the charge used for the synthesis, namely the reduction of tick PEDOTh layers (Q_g > 20 mC cm⁻²) includes more that one step, as a consequence of the formation of a two-layered polymer film.     

Synthesis and electrochemical capacitance of core-shell poly (3,4-ethylenedioxythiophene)/poly (sodium 4-styrenesulfonate)-modified multiwalled carbon nanotube nanocomposites

A noncovalent method was used to functionalize multiwalled carbon nanotubes with poly (sodium 4-styrene sulfonate). And then, the core-shell poly (3,4-ethylenedioxythiophene)/functionalized multiwalled carbon nanotubes (PEDOT/PSS-CNTs) nanocomposite was successfully realized via in situ polymerization under the hydrothermal condition. In the process, PSS served for not only solubilizing and dispersing CNTs well into an aqueous solution, but also tethering EDOT monomer onto the surface of CNTs to facilitate the formation of a uniform PEDOT coating. Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) were used to characterize the resultant PEDOT/PSS-CNTs. In addition, the PEDOT/PSS-CNTs nanocomposite (50 wt.% PEDOT) had a specific capacitance (SC) of 198.2 F g⁻¹ at a current density of 0.5 A g⁻¹ and a capacitance degradation of 26.9% after 2000 cycles, much better than those of pristine PEDOT and PEDOT/CNTs (50 wt.% PEDOT). The enhanced electrochemical performance of the PEDOT/PSS-CNTs nanocomposite (50 wt.% PEDOT) should be attributed to the high uniform system of the nanocomposite, resulting in the large surface easily contacted by abundant electrolyte ions through the three-dimensional conducting matrix.     

Development of a biomimetic chitosan film-coated gold electrode for determination of dopamine in the presence of ascorbic acid and uric acid

A gold electrode surface was modified using a dinuclear copper complex [Cu^II₂ (Ldtb)(μ-OCH₃)](BPh₄) and then coated with a chitosan film. This biomimetic polymer film-coated electrode was employed to eliminate the interference from ascorbic acid and uric acid in the sensitive and selective determination of dopamine. The optimized conditions obtained for the biomimetic electrode were 0.1 M phosphate buffer solution (pH 8.0), complex concentration of 2.0 × 10⁻⁴ M, 0.1% of chitosan and 0.25% of glyoxal. Under the optimum conditions, the calibration curve was linear in the concentration range of 4.99 × 10⁻⁷ to 1.92 × 10⁻⁵ M, and detection and quantification limits were 3.57 × 10⁻⁷ M and 1.07 × 10⁻⁶ M, respectively. The recovery study gave values of 95.2-102.6%. The lifetime of this biomimetic sensor showed apparent loss of activity after 70 determinations. The results obtained with the modified electrode for dopamine quantification in the injection solution matrix were in good agreement with those of the pharmacopoeia method.     

聚（3，4-乙撑二氧噻吩）/樟脑磺酸复合材料的合成及其电化学性能

以樟脑磺酸(HCSA)为掺杂剂,FeCl3为氧化剂,通过化学氧化聚合合成了聚(3,4-乙撑二氧噻吩)/樟脑磺酸(PEDOT/HCSA)复合材料;采用FTIR和SEM对其结构和形貌进行了表征;探讨了掺杂剂与单体摩尔比、氧化剂用量和反应时间对产品导电性能的影响;分析了产品的电化学性能。结果表明,当n〔3,4-乙撑二氧噻吩(EDOT)〕:n(樟脑磺酸):n(氯化铁)=2:1:40,反应时间41 h时,复合材料具有良好的导电性能和电化学性能,电导率为10.4 S/cm,经150次充放电老化后比容量可保持在140 F/g左右,是一种潜在的超级电容器电极材料。     

Voltammetric resolution of dopamine in the presence of ascorbic acid and uric acid at poly (calmagite) film coated carbon paste electrode

The poly (calmagite) film was synthesized on the surface of carbon paste electrode by electrochemical method. The synthesized polymer film coated electrode exhibits excellent electrocatalytic activity towards the detection of dopamine at neutral pH. The scan rate effect was found to be adsorption controlled electrode process. The concentration effect of dopamine was studied. The redox peak potentials of dopamine were depend on pH. This polymer film coated electrode was very good at simultaneous study of dopamine in the presence of high concentrated ascorbic acid and uric acid. The incorporation study was done by varying the concentration of one species while other two are kept constant. The proposed method was applied to the detection of dopamine in injection samples.     

导电聚合物PEDOT/PSS-MPEG的制备及性能

引言导电高分子既有导体材料的光电学特性,又有良好的力学性能和可加工性[1],这使得导电高分子材料具有广泛的应用前景。聚噻吩类有机导电材料[2]就是这类材料中的一种。聚噻吩的室温电导率     

Redox behavior and optical response of nanostructured poly(3,4-ethylenedioxythiophene) films grown in a camphorsulfonic acid based micellar solution

Poly(3,4-ethylenedioxythiophene) (PEDOT) films have been electropolymerized from an aqueous micellar solution comprising camphorsulfonic acid (CSA), lithium trifluoromethanesulfonate (LiCF₃SO₃) and EDOT. The inclusion of the dopants CS⁻ and CF₃SO₃⁻ in the polymer structure and an unusually high doping level of 0.54 have been ascertained by the X-ray photoelectron spectroscopy. Transmission electron microscopy and atomic force microscopy studies show that the micellar effect of CSA leads to a morphology wherein polymer particles link together to form elongated shapes and also endows the film with a surface roughness of 25-30 nm. These nanostructures permit a facile intercalation-deintercalation of anions in the film during redox cycling. Electrochemical impedance spectroscopy show that the charge transfer phenomenon at the PEDOT-electrolyte interface is dominant in the high frequency region and diffusion controlled ionic movement prevails in the low frequency regime. The use of these films as potential cathodes in electrochromic windows is rationalized not only on the basis of their high scalability and ease of processing but also due to their large coloration efficiency (123 cm² C⁻¹) and transmission modulation (50%) at a photopic wavelength of 550 nm. But further improvement in color-bleach kinetics and reproducibility of redox behavior is desirable to broaden their spectrum of utility.     

Vesicle-templating poly (3,4-ethylenedioxythiophene) hollow microspheres with enhanced electrocatalytic activity toward ascorbic acid oxidation

Poly(3,4-ethylenedioxythiophene) (PEDOT) hollow microspheres ranging from 50 to 950?nm are synthesized by chemically oxidative polymerization of 3,4-ethylenedioxythiophene using ammonium persulfate in the aqueous solution of cetyltrimethylammonium bromide (CTAB) and sodium dodecylbenzenesulfate (SDBS). Vesicles formed by CTAB and SDBS serve as templates for the formation of PEDOT hollow microspheres. The obtained PEDOT hollow microspheres were characterized by Fourier transform infrared spectroscopy, elemental analysis, X-ray photoelectron spectroscopy, and conductivity measurement. Compared to PEDOT granular particles, PEDOT hollow microspheres showed a more effective electrocatalytic activity in lowering the ascorbic acid oxidation potential.     

Selective determination of L-dopa in the presence of uric acid and ascorbic acid at a gold nanoparticle self-assembled carbon nanotube-modified pyrolytic graphite electrode

Gold nanoparticle-functionalized carbon nanotubes (AuNP-CNT) have been prepared by a novel self-assembly method. The new material has been characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) and utilized for constructing AuNP-CNT-modified pyrolytic graphite electrode (AuNP-CNT/PGE) to investigate the electrochemical behavior of L-dopa in neutral phosphate buffer solution. Compared to bare PG electrode, AuNP-CNT/PGE shows novel properties towards the electrochemical redox of L-dopa in phosphate buffer solution at pH 7.0. The oxidation potential of L-dopa shows a significant decrease at the AuNP-CNT/PGE. The oxidation current of L-dopa is about 5-fold higher than that of the unmodified PGE. Using differential pulse voltammetry (DPV) method, the oxidation current is well linear with L-dopa concentration in the range of 0.1-150 μM, with a detection limit of about 50 nM (S/N = 3). The proposed electrode can also effectively avoid the interference of ascorbic acid and uric acid, making the proposed sensor suitable for the accurate determination of L-dopa in both pharmaceutical preparations and human body fluids.     

Electrochemical Synthesis of Poly(3,4-ethylenedioxythiophene) on Steel Electrodes: Properties and Characterization

Electrodeposition of poly(3,4-ethylenedioxythiophene) by electrochemical polymerization of 3,4-ethylenedioxythiophene has been performed on steel electrodes rather than on the typically used inert electrodes (Pt, Au, graphite carbon). The polymer was generated by cyclic voltammetry, chronopotentiometry and chronoamperometry from a 10 mM monomer solution in acetonitrile with 0.1 M LiClO₄. Elemental analysis of the generated polymer indicated that the monomeric units support 0.54 positive charges balanced with CIO₄ ¹⁴⁻ counterions. Electrochemical, electrical and structural properties of the prepared material have been characterized. The good adherence of films combined with its excellent properties indicate that poly(3,4-ethylenedioxythiophene) can be a suitable material for anticorrosion applications.     

Adenosine 5′-triphosphate incorporated poly(3,4-ethylenedioxythiophene) modified electrode: a bioactive platform with electroactivity,stability and biocompatibility

Poly(3,4-ethylenedioxythiophene) (PEDOT) was potentiostatically polymerized onto gold electrode with adenosine 5′-triphosphate (ATP), an important biomolecule, as the counterion. Essential parameters to affect the impedance of the resultant polymer were studied in detail. Results show that 1.0 V, 0.1 M and 2.2 mC is the optimal deposition potential, dopant concentration and quantity of the passing charges, respectively. Surface topography was studied by AFM and the relationship between impedance and topography was discussed. Spontaneous release of ATP from PEDOT matrix was examined using UV-visible spectroscopy and impedance variation of the polymer modified electrode was monitored with electrochemical impedance spectroscopy. The results indicate that ATP could be strongly bound with the polymer in the incubation medium and thus could realize its role as a cell binder in its implantable application. In vitro test further demonstrates that PC12 cell could adhere to and grow on the PEDOT/ATP modified electrode and cell attachment percentage was much higher than that of non-biomolecule doped PEDOT modified electrode. Moreover, stability of PEDOT/ATP in the biological reducing agent of glutathione (GSH) was much better than that of polypyrrole/ATP. Our work demonstrates that PEDOT/ATP modified electrode can be of a promising bioactive platform to be used for implantable neural recording devices due to its great stability and biocompatibility.     

Preparation and characterisation of poly(3,4-ethylenedioxythiophene) and poly(3,4-ethylenedioxythiophene)/poly(neutral red) modified carbon film electrodes, and application as sensors for hydrogen peroxide

Poly(3,4-ethylenedioxythiophene) (PEDOT) films have been prepared for the first time on carbon-film electrodes (CFE) in aqueous solution using electropolymerisation by potential cycling, potentiostatically and galavanostatically. Characterisation of the modified electrodes was done by cyclic voltammetry and electrochemical impedance spectroscopy and the stability of the polymer films was probed. The coated electrodes were tested for application as hydrogen peroxide sensors, by oxidation and reduction. A novel polymer film was also formed by modification of CFE by co-electropolymerisation of EDOT and the phenazine dye neutral red (NR) – (PEDOT/PNR) with a view to enhancing the properties for sensor applications. It was found that hydrogen peroxide reduction at the PEDOT/PNR coated electrodes could be carried out at a less negative potential, the sensor performance comparing very favourably with that of other polymer-modified electrodes reported in the literature.