Electropolymerization Of Pyrrole Research Articles

Template and catalytic effects of DNA in the construction of polypyrrole/DNA composite macro and microelectrodes

Electrochemical DNA hybridization-based sensors show great promise as portable and automated analytical devices for routine screening of pathogenic or foreign nucleic acid sequences in biological samples. However, current sensor technologies still exhibit some unresolved issues which hampers their direct application into everyday life. Conducting polymers, such as polypyrrole (PPy), are increasingly being adopted as suitable platforms for DNA probe immobilization and signal transduction. Immobilization of DNA probes during pyrrole electropolymerization is a simple and efficient strategy to build composite electrodes suitable for DNA sensing. However, the effects of the probe state and sequence on PPy growth kinetics have not been studied yet. Here, we show that growth of PPy is drastically affected by the presence of guanine in the DNA probes and whether DNA is present in its single-stranded or double-stranded form. We show that some immobilization protocols may provoke irreversible oxidation of guanine moieties in the probe and that this issue deserves careful investigation as it may interfere with hybridization processes. We have also explored new procedures to build microelectrode arrays bearing immobilized DNA molecules, which are known to show beneficial properties in stirred samples. Overall, we present new techniques and concerns regarding the development of DNA-containing PPy-based composite electrodes, which may be taken into consideration for increasing genosensor reproducibility, response and performance.

Nanostructured conducting molecularly imprinted polymer for selective uptake/release of naproxen by the electrochemically controlled sorbent

A conducting molecularly imprinted polymer (CMIP) film, based on polypyrrole, was electrosynthesized for selective uptake/release and determination of naproxen. The film was prepared by incorporation of a template anion (naproxen) during the electropolymerization of pyrrole into a platinum electrode using the cyclic voltammetry method. Overoxidized polypyrrole films with cavities complementary to the template were used as a potential-induced selective recognition element in the solid-phase sorbent. Various important fabricating factors, which control the performance of the CMIP film, were investigated using fluorescence spectroscopy. The measured fluorescence intensities of released solutions were related to the concentrations of naproxen taken up into the films. Several key parameters such as applied potential and time for uptake and release were varied to achieve the optimal sorption procedure. The film template with naproxen exhibited excellent selectivity over some interference. The calibration graphs were linear in the ranges of 5×10−8 to 3×10−7molml−1 and 7×10−6 to 8×10−4molml−1, and the limit of detection was 1×10−8molml−1. The CMIP films, as the electrochemically controlled solid-phase sorbent, were applied for the selective cleanup and quantification of trace amounts of naproxen from physiological samples. Scanning electron microscopy confirmed the nanostructure morphology of the films.

Determination of benzimidazole in biological model samples using electropolymerized-molecularly imprinted polypyrrole modified pencil graphite sensor

Abstract Molecularly imprinted polymer (MIP) of benzimidazole was prepared through electropolymerization and electrodeposition of pyrrole on a pencil graphite electrode in the presence of benzimidazole as template molecule. The ability of the fabricated MIP to act as a sensor of determining benzimidazole was investigated. Preparing of MIP and quantitative measurements were performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), respectively. Several important parameters which controlling the performance of the polypyrrole and the method efficiency were investigated and optimized. The molecularly imprinted layer exhibited selectivity and sensitivity toward benzimidazole. The calibration curve demonstrated linearity over a concentration range of 3 × 10 −6 M to 5 × 10 −3 M with a correlation coefficient ( r 2 ) of 0.9920. The detection limit (based on S/N = 3) of benzimidazole was obtained 7.0 × 10 −7 M. The minimum and maximum recovery (%) through the spiking 2 mM benzimidazole to analyte free real biological matrices were obtained 85.1% (turkey) and 99.6% (chicken), respectively. A computational study based on density functional theory was performed to evaluate the template-monomer geometry and interaction energy in the prepolymerization mixture.

Study of the electrosynthesis of hollow rectangular microtubes of polypyrrole

Hollow rectangular-sectioned microtubes of polypyrrole were deposited on stainless steel by potentiostatic electropolymerization of pyrrole in the presence of an aqueous solution of salicylate. The formed films were characterized using AFM, SEM, EDS, UV and IR spectroscopies, XRD and XPS analysis methods. The initial crystallization of salicylic acid is considered to be responsible for the formation of these special morphological structures. The experimental results indicate a high content of salicylic acid and salicylate in the electrosynthesized film. The microtubes of the polymer doped with salicylate anions coexist with the acid. PPy microtubes remain on the electrode surface after extraction of the acid from the film with ethanol.

Simultaneous detection of dopamine and acetaminophen by modified gold electrode with polypyrrole/aszophloxine film

The differential pulse voltammetric method was developed for simultaneous determination of dopamine (DA) and acetaminophen (AC) using the Ppyox/AZ/Au (poly overoxidized pyrrole–aszophloxine–gold) modified electrode. Polypyrrole film was prepared by incorporation of aszophloxine (AZ) as doping anion, during the electropolymerization of pyrrole onto a gold (Au) electrode in aqueous solution using the cyclic voltammetric (CV) technique. Then the polypyrrole film was overoxidized at constant potential. Well-separated voltammetric peaks were observed for dopamine (DA) and acetaminophen (AC) with peaks separation of about 200mV. The current of the oxidation peaks showed a linear dependent on the concentrations of DA and AC in the range of 0.1–30μM and 0.2–100μM respectively. The detection limit of 0.05 and 0.08μM (S/N=3) were obtained for DA and AC respectively. The modified electrode was used for determination of DA and AC in some real samples such as human serum and tablet samples.

Electrochemical Sensing of Dopamine Using a Dodecylsulfate Doped Polypyrrole Film

A polymer-modified electrode was fabricated by the electropolymerisation of pyrrole from an ethanol solution using sodium dodecylsulfate as a dopant. The modified electrode is a highly sensitive electrochemical sensor for dopamine with a limit of detection measured as 3.8 x 10-8 mol dm-3. The sensor did not sense the common interferant ascorbic acid showing a single redox peak for dopamine in the presence of excess ascorbic acid.

Glucose biosensor based on the immobilization of glucose oxidase on electrochemically synthesized polypyrrole-poly(vinyl sulphonate) composite film by cross-linking with glutaraldehyde

In this study, a novel amperometric glucose biosensor was developed by immobilizing glucose oxidase (GOX) by cross-linking via glutaraldehyde on electrochemically polymerized polypyrrole-poly(vinyl sulphonate) (PPy-PVS) films on the surface of a platinum (Pt) electrode. Electropolymerization of pyrrole and poly(vinyl sulphonate) on the Pt surface was carried out with an electrochemical cell containing pyrrole and poly(vinyl sulphonate) by cyclic voltammetry between -1.0 and + 2.0 V (vs.Ag/AgCl) at a scan rate of 50 mV/s upon the Pt electrode. The amperometric determination was based on the electrochemical detection of H(2)O(2) generated in enzymatic reaction of glucose. Determination of glucose was carried out by the oxidation of enzymatically produced H(2)O(2) at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and optimum parameters were found to be 7.5 and 65°C, respectively. The effect of working potential was investigated and optimum potential was determined to be 0.4 V. The operational stability of the enzyme electrode was also studied. The response of the PPy/PVS-GOX glucose biosensor exhibited good reproducibility with a relative standard deviation (RSD) of 2.48%. The glucose biosensor retained 63% of initial activity after 93 days when stored in 0.1 M phosphate buffer solution of pH 7.5 at 4°C. With the low operating potential, the biosensor demonstrated little interference from the possible interferants.

Gold nanoparticle–polypyrrole composite modified TiO2 nanotube array electrode for the amperometric sensing of ascorbic acid

Titanium dioxide (TiO2) nanotubes were fabricated by anodisation of titanium foil in 0.15 M ammonium fluoride in an aqueous solution of glycerol (90 % v/v). Electropolymerisation of pyrrole and deposition of gold nanoparticles on to the TiO2 nanotube array electrode were carried out by cyclic voltammetry (CV). Electrochemical characterization of the sensor was performed by CV and electrochemical impedance spectroscopy. The morphology of the electrode was studied after every step of modification using field emission scanning electron microscope and atomic force microscope. The sensor was tested for AA and other biomolecules in phosphate buffered saline solution of pH 7 using CV, differential pulse voltammetry and amperometry. The sensor exhibited very high sensitivity of 63.912 μA mM−1 cm−2 and excellent selectivity to ascorbic acid (AA) in the presence of other biomolecules such as uric acid, dopamine, glucose and para-acetaminophen. It also showed very good linearity (R = 0.9995) over a wide range (1 μM–5 mM) of detection. The sensor was tested for AA in lemon and found its concentration to be 339 mg ml−1.

Molecularly imprinted polymers based electrochemical sensor for bovine hemoglobin recognition

A simple and efficient molecularly imprinted polymers (MIPs) based electrochemical sensor were proposed and prepared by electropolymerization of pyrrole in the presence of bovine hemoglobin (BHb) in an aqueous solution. The fabrication process of the sensor was characterized by differential pulse voltammetry and electrochemical impedance spectroscopy, in which [Fe(CN)6]3−/[Fe(CN)6]4− was used as an electrochemical active probe. The influence factors including electropolymerization cycles, scan rate, the concentration of pyrrole, and the extraction conditions were investigated in detailed. Under the optimized conditions, the experimental results showed that the MIPs based sensor possessed a fast rebinding dynamics and an excellent recognition capacity to BHb, compared to the other non-template proteins. Moreover, the prepared sensor also exhibited a dependent relationship between the concentration of template protein and peak current of [Fe(CN)6]3−/[Fe(CN)6]4−.

A solid state Cr(VI) ion-selective electrode based on polypyrrole

We report on a graphite electrode onto which polypyrrole was electrodeposited and then doped with chromate ion. This electrode can serve as a Cr(VI)-selective solid-state electrode. Electropolymerization of pyrrole was performed potentiostatically at 0.80 V (vs. SCE) using battery graphite as the working electrode in a solution containing 0.10 M of pyrrole and 20 mM of chromate. A platinum wire was used as an auxiliary electrode. The new electrode displays high selectivity, a very wide dynamic range, a sufficiently fast response time and a good shelf lifetime. It shows a linear Nernstian response over 1.0 × 10−6 to 1.0 × 10−1 M concentration range (with a slope of 26.55 ± 0.20 mV per log of concentration). The detection limit is 0.5 μM, and the pH optimum is 7.0.

Effects of solvent composition on the preparation and electroanalytical behaviors of polypyrrole modified electrodes

Conducting polypyrrole modified electrodes incorporated with alizarin red S ligands were prepared by electropolymerization of pyrrole in mixtures of water and acetonitrile. Electroanalysis of copper(II) species was performed voltammetrically. The effects of solvent systems employed for pyrrole electrodeposition on the electroanalytical behaviors of the modified electrodes were evaluated in terms of the pyrrole polymerization charge, alizarin red S coverage, copper response, and the ligand-to-metal ratio for copper analysis. Experimental results showed that the water content in the solvent mixture had strong influence on the electroanalytical performance of the polypyrrole modified electrodes. The morphology of the polypyrrole films prepared in different acetonitrile–water mixtures was examined and it indicated that there was close correlation between the film morphology and the electroanalytical behavior for copper(II) determination.

Electropolymerization of pyrrole: Dendrimers, nano-sized patterns and oscillations in potential in presence of aromatic and aliphatic surfactants

Compact, dendritic and featherlike growth morphologies, growth kinetics and electrical conductivity of aggregates obtained during electropolymerization in surfactant added systems (A) pyrrole–dodecyl benzene sulfonic acid (DBSA)–H2O (B) pyrrole–DBSA–sodium dodecyl sulfate (NaDS)–H2O and (C) pyrrole–DBSA–cetyl trimethyl ammonium bromide (CTAB)–H2O were investigated using vertical anode and circular cathode. Effect of time, field intensity, [DBSA], [NaDS] and [pyrrole] were studied for systems A, B, and C. Different transitions are seen in all the systems at different conditions. It is observed that growth is highest in system B. Growth rate follows the sequence B>A>C. Growth kinetics was studied and electric potential oscillations were monitored as a function of time during electropolymerization in systems A–C at different experimental conditions. On addition of NaDS and CTAB, particle size was increased and decreased respectively. Growth rate was found to be increased in system B due to the increase in the anodic charge of the film, leading to the better protonation of polypyrrole and decreased in system C due to coordination of CTAB with the growing polypyrrole chain. The formation of polypyrrole aggregates has been explained on the basis of diffusion limited aggregation (DLA) model. Fractal dimension of a pattern was found to be 1.69, in agreement with DLA model. Electropolymerized aggregates were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric studies (TGs), powder X-ray diffraction (XRD) and electrical conductivity measurements. Nanosized polypyrrole was formed in the range 50–100nm as evident by SEM and TEM studies. During electropolymerization, oscillations in potential were monitored as a function of time at different experimental conditions. Nature of oscillations was periodic.

Voltammetric Determination of Salicylic Acid by Molecularly Imprinted Film Modified Electrodes

A highly selective and sensitive voltammetric sensor for salicylic acid was introduced. The sensitive layer was prepared by electropolymerization of pyrrole on a glassy carbon electrode in the presence of salicylic acid as a template. The template could be removed effectively by a two-step method. The first step was fixed potential peroxide and the second step was alkali solution washing. A wide dynamic linear range of 5.0 × 10−9 to 1.0 × 10−3 mol · L−1 was obtained. The imprinted sensor could be easily fabricated and showed a stable and reproducible response without any influence of interferents commonly existing in drug combination samples.

Electropolymerization of pyrrole in ionic liquid microemulsion

AbstractThe direct electropolymerization of pyrrole in [BMIM]PF6 microemulsion was investigated for the first time. The H2O/TX‐100/[BMIM]PF6 (W/IL), bicontinuous (BC), [BMIM]PF6/TX‐100/H2O (IL/W) subregions can be used as electrolytes for pyrrole electropolymerization. The use of IL microemulsion remarkably reduces the amount of IL. Furthermore, electrochemical measurements indicated that W/IL microemulsion was the optimal medium and its polymerization rate was the fastest. Compared with molecular solvent system (0.25 mol L−1 [BMIM]PF6/acetonitrile) and neat [BMIM]PF6, the resultant films electrodeposited in W/IL microemulsion possessed excellent electrochemical activity and uniform morphology. All the results indicated that the H2O/TX‐100/[BMIM]PF6 microemulsion as electrolyte medium is the most suitable for electropolymerization of pyrrole. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Effect of the surface roughness of conducting polypyrrole thin‐film electrodes on the electrocatalytic reduction of nitrobenzene

AbstractConducting polypyrrole (PPy) thin‐film electrodes were prepared by the electropolymerization of pyrrole on gold‐coated glass plates. Films of various roughnesses were obtained by the variation of the scan rates during electropolymerization. These thin films were modified by doping with 6mM of the dopant NiCl2. The surface morphology of the films was studied by scanning electron microscopy and atomic force microscopy (AFM), which suggested films prepared with a high scan rate were rougher in nature than the films produced with a low scan rate. The electrocatalytic reduction of nitrobenzene was carried out with these electrodes with the cyclic voltammetry technique in acetonitrile containing 0.1M HClO4 as a supporting electrolyte. The various results obtained show that the conducting PPy thin‐film electrodes were catalytically active toward the electroreduction process. The modified PPy film electrodes doped with NiCl2 were more active toward nitrobenzene electroreduction than the PPy film alone. The results indicate that the roughness of the films played a very important role in determining their catalytic activity. The PPy films that were more rough in nature were catalytically more active than the smooth films; this may have been due to the availability of more reactive sites in the case of rough films. The apparent diffusion coefficients of the PPy film electrodes were also calculated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The response behavior of PPy-DB18C6 electrode to terbium(III) in acetonitrile and its thermodynamic application

Polypyrrole modified electrode prepared by electropolymerization of pyrrole in the presence of a complexing ligand, dibenzo-18-crown-6(DB18C6), was prepared and investigated as a Tb3+-selective electrode in acetonitrile. The potentiometric response of the electrode was linear within the Tb3+ concentration range 1×10−5–1×10−2M with a Nernstian slope of 20.9mVdecade−1 in AN. The electrode was applied to study the complexation of the terbium(III) ion in acetonitrile with such other basic aprotic solvent molecules (D) as dimethyl sulfoxide, N,N-dimethyl formamide, propylene carbonate and pyridine. The successive complex formation constant (βi) and Gibbs energies of transfer (ΔGtr) of Tb3+ in AN in relation to such D were obtained.

Graphene oxide/polypyrrole nanocomposites: one-step electrochemical doping, coating and synergistic effect for energy storage

We introduce a facile method for the construction of graphene oxide/polypyrrole (GO/PPy) nanocomposites via one–step coelectrodeposition. In this process, the relatively large anionic GO serves as a weak electrolyte and is entrapped in the PPy nanocomposites during the electropolymerization of pyrrole, and also acts as an effective charge-balancing dopant within the PPy film. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results demonstrate that the GO/PPy nanocomposites are successfully synthesized. The obtained GO/PPy nanocomposites exhibit good electrochemical properties and cycling performance, indicating a synergistic effect of PPy and GO. Taking its higher capacitance, lower cost and shorter processing time into consideration, GO may be a good choice for the fabrication of electrochemical supercapacitors based on conducting polymer nanocomposites. It should be noted that this coelectrodeposition is also applicable for the graphene oxide/poly[3,4-ethylenedioxythiophene] (GO/PEDOT) nanocomposites. Moreover, this facile and effective approach for the synthesis of GO/conducting polymer nanocomposites further extends the application of GO and should be very promising for the fabrication of inexpensive, high-performance electrochemical supercapacitors.

An Amperometric Sensor for Sunset Yellow FCF Detection Based on Molecularly Imprinted Polypyrrole

An electrochemical method for fast detecting the concentration of sunset yellow FCF in wine samples was developed in this study. The sensor based on imprinted films which fabricated by electropolymerization of pyrrole on a glassy carbon electrode in the presence of sunset yellow FCF as the template. Comparing to the polypyrrole non-imprinted modified (NIP) electrode, the polypyrrole molecularly imprinted polymer (MIP) electrode improved the electrochemical performance of the sensor significantly. The peak current at about 0.26 V was linear with the concentration of sunset yellow FCF from 0.4 to 2 μM and from 2 to 8 μM. It can be used for more than 10 times to maintain a stable response result. The sensor had the good selectivity on sunset yellow FCF, amaranth and tartrazine, which the selection factors were 1.00, 0.80 and 0.85，respectively.

Three-dimensional graphene–polypyrrole hybrid electrochemical actuator

The advancement of mechanical actuators benefits from the development of new structural materials with prominent properties. A novel three-dimensional (3D) hydrothermally converted graphene and polypyrrole (G-PPy) hybrid electrochemical actuator is presented, which is prepared via a convenient hydrothermal process, followed by in situ electropolymerization of pyrrole. The 3D pore-interconnected G-PPy pillar exhibits strong actuation responses superior to pure graphene and PPy film. In response to the low potentials of ±0.8 V, the saturated strain of 3D G-PPy pillar can reach a record of 2.5%, which is more than 10 times higher than that of carbon nanotube film and about 3 times that of unitary graphene film under an applied potential of ±1.2 V. Also, the 3D G-PPy actuator exhibits high actuation durability with high operating load as demonstrated by an 11 day continuous measurement. Finally, a proof-of-concept application of 3D G-PPy as smart filler for on/off switch is also demonstrated, which indicates the great potential of the 3D G-PPy structure developed in this study for advanced actuator systems.

Actuator of double layer film composed of carbon nanotubes and polypyrroles

We fabricate double layer films composed of millimeter-long ‘super-growth’ carbon nanotube (SG-SWNT) and polypyrrole (PPy) by electropolymerization of pyrrole on the SG-SWNT film surface under various conditions. Electrical and mechanical properties as well as morphologies of the obtained double layer films are studied by a four-probe DC current method, stress–strain measurements and scanning electron microscope (SEM) measurements. The growth process of PPy on the SG-SWNT film during electropolymerization is also investigated in detail. SG-SWNT/PPy double layer films show higher electrical conductivities and breaking strengths compared to both SG-SWNT and PPy single layer films. The fracture surface morphologies of the double layer films revealed that very fine fibrous SG-SWNTs came out on the cleavage section of PPy particles. Such a interconnected structure between SG-SWNTs and PPy was supposed to allow a new electrical conductive pass and reinforce the strength of the composite materials. Actuation performances of the SG-SWNT/PPy double layer films were also demonstrated in an aqueous solution. One of the features of this actuator is reversion of displacement direction depending on scan rate range when a relative amount of PPy component is large. This reversion of displacement direction is supposed to be based mainly on volume changes of PPy governed by several factors including ion movement, while volume changes of both SG-SWNT and PPy layers should contribute the actuation behavior.