Polypyrrole Research Articles

Analysis of effect of nanoporous alumina substrate coated with polypyrrole nanowire on cell morphology based on AFM topography

In this study, in situ electrochemical synthesis of polypyrrole nanowires with nanoporous alumina template was described. The formation of highly ordered porous alumina substrate was demonstrated with Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). In addition, Fourier transform infrared analysis confirmed that polypyrrole (PP) nanowires were synthesized by direct electrochemical oxidation of pyrrole. HeLa cancer cells and HMCF normal cells were immobilized on the polypyrrole nanowires/nanoporous alumina substrates to determine the effects of the substrate on the cell morphology, adhesion and proliferation as well as the biocompatibility of the substrate. Cell adhesion and proliferation were characterized using a standard MTT assay. The effects of the polypyrrole nanowires/nanoporous alumina substrate on the cell morphology were studied by AFM. The nanoporous alumina coated with polypyrrole nanowires was found to exhibit better cell adhesion and proliferation than polystyrene petridish, aluminum foil, 1st anodized and uncoated 2nd anodized alumina substrate. This study showed the potential of the polypyrrole nanowires/nanoporous alumina substrate as biocompatibility electroactive polymer substrate for both healthy and cancer cell cultures applications.

Preparation of Polypyrrole/Nuclear Fast Red Films on Gold Electrode and Its Application on the Electrocatalytic Determination of Methyl‐dopa and Ascorbic Acid

AbstractA novel voltammetric method using the Ppyox/NFR/Au (poly pyrrole – nuclear fast red – gold) modified electrode was developed for simultaneous measurement of various combinations of ascorbic acid (AA) and methyldopa (MDA). Polypyrrole film was prepared by incorporation of nuclear fast red (NFR) as doping anion, during the electropolymerization of pyrrole onto a gold (Au) electrode in aqueous solution using cyclic voltammetric (CV) method, and then it was overoxidized at constant potential. Differential pulse voltammetry was utilized for the measurement of both analytes using modified electrode. Well‐separated voltammetric peaks were observed for ascorbic acid (AA) and methyldopa at the Ppyox/NFR/Au modified electrodes with peak separation of 0.210 V. It has been found that under optimum condition (pH 3.0), the oxidation of AA and MDA at the surface of the electrode occurs at a potential about 260 and 50 mV less positive than unmodified Au electrode respectively. The current catalytic oxidation peaks showed a linear dependent on the concentration of AA and MDA in the range of 9.0×10−6 to 1.0×10−3 and 1.0×10−7 to 2.0×10−5 mol L−1 respectively. The detection limit of 5.8×10−6 and 5.0×10−8 mol L−1 (S/N=3) were obtained for AA and MDA respectively. The modified electrode was used for determination of AA and MDA in some real samples such as human serum and tablet.

Chemically Modified PPyCOOH Microtubes as an Affinity Matrix for Protein Purification

AbstractNovel affinity microtubes, with high ligand content and adsorption capacity of proteins, were fabricated by functionalization of the carboxyl group on the inner and outer surfaces of conductive polymer, poly(1‐(2‐carboxyethyl)pyrrole) (PPyCOOH) microtubes with iminodiacetic acid (IDA), which affords the active site to form metal‐IDA chelates used for immobilized‐metal affinity chromatography. After immobilization with copper ions, the microtubes were used to recover a model protein, bovine hemoglobin, from red cell lysate in a batch manner. The protein adsorption indicates that the affinity microtubes exhibit a high adsorption capacity and good selectivity, and the adsorption isotherm fitted the Freundlich model well. Elution of the protein showed that the desorption ratio was up to 99.5% in 3 h, using 0.2 M CH3COOHCH3COONa buffer solution (pH = 3.6) as the desorption agent. The adsorption‐desorption cycle was repeated 10 times using the same microtubes without significant loss in the hemoglobin adsorption capacity.magnified image

Biomimetic study of the Ca2+-Mg2+ and K+-Li+ antagonism on biologically active sites: new methodology to study potential dependent ion exchange

Competitive divalent (magnesium and calcium) or monovalent (potassium, lithium and sodium) ion exchange and its influence on a membrane potential formation was studied at biological ligands (BL) such as adenosine triphosphate (ATP), asparagine (Asn) and glutamine (Gln) sites. The sites are dispersed electrochemically in membranes made of the conducting polymers (CPs)--poly(N-methylpyrrole) (PMPy) and poly(pyrrole) (PPy). The membranes are made sensitive to calcium and magnesium or to potassium, sodium and lithium by optimized electrodeposition and soaking procedures supported by the study of membrane topography and morphology. Distinctively different electrochemical responses, i.e. electrical potential transients or currents, are observed in the case of "antagonistic" calcium and magnesium or potassium and sodium/lithium ion pairs. Dissimilarity in the responses is ascribed to a difference between on site vs. bulk concentrations of ions, and is dictated by different transport properties of the ions, as shown by using the Nernst-Planck-Poisson (NPP) model and the diffusion-layer model (DLM). The method described allows inspecting potential-dependent competitive ion-exchange processes at the biologically active sites. It is suggested that this approach could be used as an auxiliary tool in study of potential dependent block in realistic membrane channels, such as Mg block in the N-methyl D-aspartate receptor channel (NMDA).

Preparation and electrochemical nanogravimetric study on the ruthenium(III) trichloride-polypyrrole nanocomposite

Nanocomposites were prepared by in situ redox intercalative polymerization method, in which α-RuCl 3 microcrystals were soaked in pyrrole. Polypyrrole (PP) was formed as a result of the intercalation of pyrrole into the layered structure of RuCl 3 crystal and the reaction between pyrrole and the host material. The appearance of polypyrrole was proven by infrared spectroscopy. The as-formed (PP) z+ (RuCl 3) z− nanocomposites were attached to paraffin-impregnated graphite or gold surfaces and studied by cyclic voltammetry and electrochemical nanogravimetry. The redox behaviour of the composite shows the electrochemical transformations of both the polypyrrole and RuCl 3. The redox waves of PP are similar to those observed for very thin PP films. It attests that the response is originated from monolayer-like PP film situated between RuCl 3 layers. The transport of the charge-compensating ions reflects the variation of the oxidation states of both PP and RuCl 3. The nanocomposites behave as self-doped layers in the potential region when both constituents are charged, i.e., PP is partially oxidized while RuCl 3 is partially reduced, since the electroneutrality is assured by mutual charge compensation. When PP is reduced, cations enter the layer to counterbalance the negative charge resulted from the reduction of Ru(III) to Ru(II). It was also found that the intercalation of water molecules is – albeit still substantial – smaller than that of pure RuCl 3 microcrystals which is related to the presence of PP between the RuCl 3 layers.

Electrochemical/Electrospray Mass Spectrometric Studies of Electrochemically Stimulated ATP Release from PP/ATP Films

Polypyrrole (PP)/adenosine triphosphate (ATP) was chosen as a conducting polymer/anionic drug model to serve as a bioactive releasing material for ATP. The process of ATP release from PP/ATP films was investigated for the first time by electrochemical electrospray ionization mass spectrometry (EC/ESMS). This technique allowed the simultaneous and direct detection of ATP and its related species during electrochemical release. In the experiments, suitable solvent conditions were found for both the electrochemical release and the electrospray mechanisms. EC/ESMS results showed that continuous potential cycles allowed a higher ATP release rate than potential steps. It was also found that the film thickness is an important factor affecting the rate and the amount of electrochemical ATP release.

Inspecting the Fractality of Polypyrrole in Nanoscale

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Carboxylic Acid-Functionalized Conductive Polypyrrole as a Bioactive Platform for Cell Adhesion

Electroactive polymers such as polypyrrole (PPy) are highly attractive for a number of biomedical applications, including their use as coatings for electrodes or neural probes and as scaffolds to induce tissue regeneration. Surface modification of these materials with biological moieties is desired to enhance the biomaterial-tissue interface and to promote desired tissue responses. Here, we present the synthesis and physicochemical characterization of poly(1-(2-carboxyethyl)pyrrole) (PPyCOOH), a PPy derivative that contains a chemical group that can be easily modified with biological moieties at the N-position of the polymer backbone. FTIR, XPS, and fluorescence microscopy were used to demonstrate the successful incorporation of carboxylic acid (-COOH) functionality into PPy materials, and a four-point probe analysis was used to demonstrate electrical conductivity in the semiconductor range. Human umbilical vascular endothelial cells (HUVECs) cultured on PPyCOOH films surface-modified with the cell-adhesive Arg-Gly-Asp (RGD) motif demonstrated improved attachment and spreading. Thus, PPyCOOH could be useful in developing PPy composites that contain a variety of biological molecules as bioactive conducting platforms for specific biomedical purposes.

Electropolymerization of Bilayer with Phosphonic Acid Tethers for Immobilization of Biomolecules

Bilayer consisting of polypyrrole, PPy, as the inner and poly(2,5-dithienyl-(-3-phosphorylpropyl)pyrrole, as the outer layers was electropolymerized in layer-by-layer steps. Due to the presence of phosphonic acid functionality tethered to the backbone of outer polymer, the system is capable of binding organic and inorganic bases and offers an easy and conven- ient access to sensor devices. The ion transport through the polypyrrole film depends on its thickness. The thin layer of does not hinder the redox and ion-transport characteristics of the PPy layer.

Polypyrrole - A Conducting Polymer for Biomedical Applications

The feasibility of functionalizing the surfaces of the electrically conducting polypyrrole (PPY) film with biomolecules was demonstrated with an enzyme, glucose oxidase, and an anticoagulant, heparin. The biomolecules remained active after immobilization and the choice of the linkage groups attaching the biomolecules to the PPY surface can play an important role in the activity of the biomolecules. The use of aviologen to link a wide linear range and high electrochemical response. Similarly, poly(ethylene glycol) methacry-late (PEGMA) graft copolymerized PPY films immobilized with heparin are more efficient in minimizing platelet adhesion than that without the PEGMA. An advantage of using electrically conductive PPY films as a substrate is that electrical stimulation can be carried out to further enhance the effect of the heparin.

Magnesium and Calcium-Dependent Membrane Potential of Poly(Pyrrole) Films Doped with Adenosine Triphosphate

Polypyrrole-adenosinotriphosphate (PPy-ATP) films (membranes) were electropolymerized on platinum or glassy carbon and made sensitive to magnesium and calcium ions by conditioning. Close-to-Nernstian potentiometric sensitivity was observed for the films under equilibrium. During equilibration provoked by the change in concentration of magnesium and/or calcium ions, a characteristic transitory potential response of PPy-ATP film was observed. This behaviour is ascribed to the surface concentration changes of magnesium and calcium ions during equilibration via ion-exchange at ATP membrane sites. It is suggested that PPy-ATP film may be used as a model membrane to study the potential formation of the biological membranes, where the calcium and magnesium interaction with ATP is of primary importance.

Ordered Conducting Polypyrrole Doped with Sulfopropyl Ether of β-Cyclodextrin

Ordered Conducting Polypyrrole Doped with Sulfopropyl Ether of β-Cyclodextrin

Development of Conducting Polymer Coated Screen-Printed Sensors for Measurement of Volatile Compounds

A simple approach that allows production of a range of conducting polymer coated screen-printed carbon track sensors on flexible polyester substrate has been developed. The most effective method involved pretreating the sensor surface with a chemically deposited poly(pyrrole) chloride layer followed by subsequent electrodeposition of the desired PPy film. The analytical performance in terms of sensitivity and selectivity was found to be similar to sensors produced using microlithography to form gold tracks on silicon substrates. The low cost and ease of fabrication make these sensors an attractive alternative to existing devices for use in odor identifications and discrimation.

Non-linear I–V characteristics of polypyrrole micro-line synthesized using scanning probe microscope

AbstractWemeasuredtemperaturedependenceofvoltage–currentcharacteristicsofelectrochemicallypolymerizedpolypyrroleinmicronscaleusingscanningprobemicroscope.Themorphologyandthemagnitudeofroomtemperatureresistivity,q RT ¼ 0:016Xcm,aresimilartootherelectrochemicallysynthesizedpolypyrrole.I–Vcharacteristicsbecamenon-linearforT < 100Kandcanbefittedtofluctuation-inducedtunnelingconductionmodel. 2002ElsevierScienceB.V.Allrightsreserved. PACS:72.80.-r;72.80.Le;73.63.-b;73.63.NmKeywords:Polypyrrole;Micor-line;Electrochemicalsynthesis;Scanningprobemicroscope;Non-linearI-Vcharacteristics 1.IntroductionConjugatedpolymerhasinterestingphysicalproper-tiesincludingmetallicbehaviourandeventhesuper-conductivity [1] as well as applicability to electronicdevices such as LED [2] or field-effect transistor orconductivewireetc.Conductingpolymersuchaspoly-acetylene (PA), polypyrrole (PPy), polythiophen (PT)andpolyaniline(PANI)haslongbeeninvestigatedtoelucidate their intrinsictransport properties owing totheirlowdimensionality.Thelocalexcitationssuchassoliton [3], polaron and bipolaron are suggestedfor their conducting carriers. However the transportmechanisminconductingpolymerinnanoscaleisnotunderstoodwellyet.Recentlywehavereportedtrans-portmeasurementsofPAnanofibernetworkinmicronscale[4]andthatofPAsinglenanofiberin100nmscale[5].ContrarytothefibrillarstructureofPA,thegranularstructureofelectrochemicallypolymerizedconductingpolymermakesitdifficulttoapplythenanopatternedarrayofelectrodesfortheelectricalmeasurement.Inthecaseofusingtemplatesuchasanodicaluminumoxide(AAO) or zeolite, we can polymerize the conductingpolymer inside the template [6] and then separate itfromthetemplate.Othermethodstosynthesizealinearstructure of conducting polymer is using SPM localoxidation[7],e-beamirradiationtoPANI[8]orpoly-octylthiophene [9], self-assembled monolayer (SAM)pattern [10] and Langmuir–Bloddgett (LB) technique[11].STMlocaloxidationhassomedifficultiestomakealinearstructureinnarrowscaleduetotherandomnessofthegrowthdirection.UsingaSAMhaslimitationonthestamptogeneratetheSAMpatternanditisali-thography dependent technique. Here we present thetransport measurements of PPy line that is electro-chemicallypolymerizedbybiasingtothemetalcoatedSPMtipontopofthepatternedelectrodes.2.ExperimentalMicron and submicron electrodes for transportmeasurement were patterned using JEOL JBX5D-IIe-beamlithographysystem.300nmSiO

Preparation and Electrochemical Characterization of Poly(pyrrole) Films Modified by Cobalt Particles

The electrochemical preparation of characterization of poly(pyrrole) / cobalt stable composites were investigated in this work. Using cyclic voltammetry, a new redox couple was identified in the composite compared to poly(pyrrole) films. In addition, cobalt modifies the polymer redox process displacing the peak potential. The morphological results indicate structural changes in the polymer and the composite.

Nanotubes of Conducting Polyaniline and Polypyrrole

Nanotubes of Conducting Polyaniline and Polypyrrole

Structural, electrical, and optical studies of plasma‐polymerized and iodine‐doped poly pyrrole

AbstractAn attempt was made to study the structural, electrical, and optical properties of plasma‐polymerized pyrrole and iodine‐doped pyrrole. A comparative study of the IR spectra of the monomer and polymer pyrrole gives information that the ring structure is retained during plasma polymerization. Iodine doping considerably increases the conductivity of the polymer film and decreases the optical band‐gap energy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1856–1859, 2002

A printable glucose sensor based on a poly(pyrrole)-latex hybrid material

A printable glucose sensor was obtained by immobilisation of glucose oxidase onto the surface of poly(pyrrole)-coated latex spheres, which were mixed with a conducting ink. The obtained hybrid material was able to amperometrically detect glucose under aerobic as well as anaerobic conditions, without the use of electron mediators. Since all of the steps involved in the preparation of this latex-poly(pyrrole)-based ink are performed in solution, in-expensive mass production will be possible. A possible mechanism for this sensor is proposed based on the direct communication between the enzyme and the conducting polymer under anaerobic conditions.

Multiple hopping conduction in interpenetrating polymer network composites of poly pyrrole and poly (styrene-co-butyl acrylate)

Interpenetrating polymer network composites of poly pyrrole and FeCl3 impregnated poly (styrene-co-butyl acrylate) have been synthesized by chemical route. ac conductivity measurements have been carried out on these specimens in the frequency range 100 to 2 MHz over temperatures varying from 110 to 350 K. Detailed analyses of the results show that a multiple hopping conduction mechanism is operative in all the samples. Two activation energies viz., ∼(0.05–0.08) eV and ∼0.02 eV are found which are believed to arise due to interchain and intrachain hopping of polarons, respectively.

Study of DNA hybridization by photocurrent spectroscopy

Photoelectrochemical properties of poly(pyrrole―pyrrole-oligonucleotide) copolymer synthesized by cyclic voltammetry and the same copolymer in presence of complementary oligonucleotides and alternatively in presence of non-complementary oligonucleotides were investigated by photocurrent spectroscopy. The DNA hybridization and adsorption kinetics have also been monitored in real-time using the same technique.