Polypyrrole

The stability and sensitivity are two main factors are important to practical sensors, the strain sensor is fabricated by fabrics is coated by conducting polymer Polypyrrole it's an now approach, this also get in good strain sensing properties, and stability of long period. The reason for Polypyrrole is a good environmental stability and electrical conductive material. In this paper we prepared Knitted cotton-lycra blended fabric were coated with conductive polymer of Polypyrrole by using Diffusive chemical polymerization technique. The prepared conductive fabric were characterized by using Fourier transform infra red spectroscopy (FTIR) for chemical vibrational bonding analysis, structural characterization were analysis by X-Ray diffraction spectroscopy (XRD) and micro level image of morphological structures of polypyrrole particles were analysis by using Scanning Electron Microscope spectroscope (SEM). The FTIR analysis clearly indicate that the fabric was over coated by conductive polymer functional groups, The XRD revel that fabric was changed its own crystallinity nature to amorphous nature, particle size variation between 4nm to 12nm range and SEM analysis clearly showing that conductive polymer of Polypyrrole nano level particles are coated on deep in each knitting yarns.

Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole(Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention ispaid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties ofthis polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical targetDNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinityagents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered.

In this study graphite electrodes modified by a thin DNA-imprinted polypyrrole layer, which was able to bind specific target-DNA, are reported. For this aim, electrochemical synthesis of polypyrrole was performed on a pencil graphite electrode by cyclic voltammetry (CV) or by potential pulse sequences (PPS). The modified electrode surface was used for electrochemical determination of target-DNA by differential pulse voltammetry. According to our best knowledge this is a first report on the application of DNA-imprinted polymer for the determination of target-DNA. The results showed that the molecularly imprinted polypyrrole (MIPPy) layer that formed on the carbon electrode surface was sensitive for target-DNA, while the nonimprinted polypyrrole layer was not sensitive to the same target-DNA. Comparison of electrodes modified using PPS and CV techniques is presented.

Authors: Norberto T. Alcantara1*, Maria Carla F. Manzano1, Enrique M. Manzano2
1Physics Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
2Electronics and Communications Engineering Department, De La Salle University, 2401 Taft Ave. Manila, 0922 Philippines
*Corresponding author: norberto.alcantara@dlsu.edu.ph

ABSTRACT: Galvanostatic and galvanodynamic methods of electrochemical deposition were employed to fabricate conducting polypyrrole (PPy) film electrodes for supercapacitor applications. In this method, zinc oxide- and sodium p-toluenesulfonate- doped film electrodes were electrochemically synthesized in an aqueous solution containing 0.10M pyrrole as monomer and 0.12M sodium p-toluenesulfonate (Na-pTS) as dopant and 0.1M zinc oxide (ZnO) as co-dopant. A two-electrode electrochemical cell was used, and for counter and working electrodes, stainless-steel plates. The applied current density during synthesis was kept at 4mA/cm2 with varying duty cycle of 25%, 50%, 75% and 100%, respectively. The thickness and surface morphology of the Zno/NapTS/PPy films grown were obtained using scanning electron microscopy. The ZnO/NapTS/PPy films have average thickness ranging from 30.60 μm to 1688.0 μm. The surface morphology of ZnO/NapTS/PPy film synthesized at constant current (100% duty cycle) exhibits lamellar and spherulite structures associated with increased conductivity. The measured AC resistance of the ZnO/NapTS/ PPy films ranged from 0.64 Ω to 3.9 Ω, with the films synthesized at 100% duty cycle showing the lowest AC resistance.

Key words: supercapacitor, conducting polymers, polypyrrole

Electrically conductive composites were prepared via the chemical oxidative polymerization of pyrrole monomer in polystyrene(PS) and zinc neutralized sulfonated polystyrene(Zn-SPS) films under supercritical carbon dioxide(SC-CO2) circumstance. The strong swelling effect of SC-CO2 made polypyrrole(PPy) particles not only formed on the surface, but also incorporated into the film, resulting in a homogenous structure and a relatively higher conductivity. By comparison, the composite prepared in aqueous solution shows a skin-core structure and a conductivity of 3 to 4 orders of magnitude lower than that of the former due to the diffusion controlled process of pyrrole monomer. The percolation thresholds of PS/PPy and Zn-SPS/PPy composites are 6.2% and 2.7% of volume fractions of PPy, respectively, much lower than a theoretically predicted value of 16%. Moreover, the conductive composites prepared under SC-CO2 Circumstance show higher thermal stabillty, especially in the high-temperature region.
Chemical Journal of Chinese Universities -Chinese Edition- 04/2006; 27(4):771-774

ABSTRACT This article verifies the hysteresis phenomenon in heat–voltage curves of polypyrrole-coated electrospun nanofibrous and regular fibrous mats. A third-order polynomial model fits the heat–voltage data better than a second-order polynomial model. It was also observed that the hysteresis loop area of nanofibrous and regular fibrous mats increases with decreasing fiber diameter. Moreover, the curvature of the hysteresis loops is significantly affected by the fiber diameter. In fact, the slope of the curvatures increases with decreasing fiber diameter.

In this study some affinity and dielectric properties of molecularly imprinted (MIP) conducting polymer-polypyrrole (Ppy) based thin films were evaluated. Films of polypyrrole molecularly imprinted with theophylline (MIP-Ppy) and non-imprinted polypyrrole (NIP-Ppy) were formed on boron doped silicon (Si) substrates in order to evaluate the efficiency of Ppy to bind theophylline. The substrates were modified with boron-doped oxygen terminated nanocrystalline diamond (B:NCD:O) The dielectric properties of B:NCD:O/Ppy-based multi-layered structures were analyzed using spectroscopic ellipsometry and spectrophotometric techniques. Electrochemical impedance spectroscopy was applied for the investigation of kinetics of theophylline interaction with MIP-Ppy and NIP-Ppy. The sensitivity of molecularly imprinted and non-imprinted polymer films was analyzed by injection of different theophylline concentrations. Assuming that Ppy film electrical capacitance change is a result of Ppy dielectric constant change induced by absorbed theophylline molecules, the electrical capacitance change (ΔC) kinetics at different concentrations of theophylline was analyzed using first pseudo order kinetic equation. The dissociation equilibrium constant KD of MIP-Ppy/theophylline complex at room temperature was calculated as 1.7·10-8 M, and Gibbs free energy change (ΔG) of MIP-Ppy/theophylline complex formation was calculated as-43.5 kJ/mol. It was concluded that molecularly imprinted polypyrrole thin film could be used for the detection of theophylline.

Several types of polyaniline (PANI) and polypyrrole (Ppy) nanocomposites with embedded glucose oxidase (GOx) and gold nanoparticles (AuNPs) were formed by enzymatic polymerization of corresponding monomers (aniline and pyrrole) in the presence of 6 and 13 nm diameter colloidal gold nanoparticles (AuNPs (6nm) or AuNPs (13nm) , respectively) or chloroaurate ions (AuCl 4 −). Glucose oxidase in the presence of glucose generated H 2 O 2 , which acted as initiator of polymerization reaction. The influence of polymerization bulk composition and pH on the formation of PANI-and Ppy-based nanocomposites was investigated spectrophotometrically. The highest formation rate of PANI-and Ppy-based nanocomposites with embedded glucose oxidase and gold nanoparticles (PANI/AuNPs-GOx and Ppy/AuNPs-GOx, respectively) was observed in the solution of sodium acetate buffer, pH 6.0. It was determined that the presence of AuNPs or AuCl 4 − ions facilitate enzymatic polymerization of aniline and pyrrole.

Polypyrrole (PPy) was synthesized by chemical oxidative polymerization technique using monomer Pyrrole and ammonium per sulphate as an oxidant in a ratio of 1:1. Thin films of polypyrrole were prepared by dissolving polypyrrole in m-cresol and cast using spin coating technique on glass substrates. Thin films of polypyrrole were characterized by X ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infra red spectroscopy (FTIR), UV visible spectroscopy, Raman spectroscopy and electrical resistivity measurements by four probe method.

Polypyrrole/Zinc oxide (ZnO) Nanocomposites were synthesised by chemical oxidative polymerization of Pyrrole with ZnO nanoparticles. The synthesised Nanocomposites of Polypyrrole/ZnO material is used to prepare thin film on glass substrates by spin coating method. The prepared Nanocomposites thin films were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and Scanning electron microscopy (SEM).

Taguchi method was successfully implemented in the robust design and development of Polypyrrole synthesis employing inverted emulsion polymerization technique using methanesulfonic acid as a novel dopant along with Potassium persulfate as an oxidant. Polypyrrole salt was obtained in a very high percent yield (83.77 %) with respect to the amount of pyrrole used and the reaction time was considerably reduced (1 hour and 10 minutes) as compared to previously reported synthesis methods. The settings of the process parameters were determined by using Taguchi's experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of one way variance (ANOVA), and regression analyses are employed to find the optimal process parameter levels and to analyze the effect of these parameters on percent yield of Polypyrrole salt.

Several types of polyaniline (PANI) and polypyrrole (Ppy) nanocomposites with embedded glucose oxidase (GOx) and gold nanoparticles (AuNPs) were formed by enzymatic polymerization of corresponding monomers (aniline and pyrrole) in the presence of 6 and 13 nm diameter colloidal gold nanoparticles (AuNPs (6nm) or AuNPs (13nm) , respectively) or chloroaurate ions (AuCl 4 −). Glucose oxidase in the presence of glucose generated H 2 O 2 , which acted as initiator of polymerization reaction. The influence of polymerization bulk composition and pH on the formation of PANI-and Ppy-based nanocomposites was investigated spectrophotometrically. The highest formation rate of PANI-and Ppy-based nanocomposites with embedded glucose oxidase and gold nanoparticles (PANI/AuNPs-GOx and Ppy/AuNPs-GOx, respectively) was observed in the solution of sodium acetate buffer, pH 6.0. It was determined that the presence of AuNPs or AuCl 4 − ions facilitate enzymatic polymerization of aniline and pyrrole.

PPy-CdS nanocomposite and multilayer thin film was deposited on Al substrate using electrodeposition technique. The presence of CdS particle in the composite film was proved using XRD and Micro-Raman spectroscopy. The roughness of the composite film was very low and it to be 4.96 nm. The fractal self-similarity of the composite films was estimated as 1.06. The resistance of PPy film along the polymer chain (sheet resistance) was 92.2 Ω and the resistance across the polymer chain (volume resistance) was 9.7 KΩ. However, the value of sheet resistance was 19.3 KΩ and the volume resistance was 43.6 KΩ for PPy-CdS nanocomposites film. Polymers acted as a corrosion protection layer for CdS nanoparticles. The rise and decay time constant of PPy-CdS nanocomposites film were obtained as 150s and 200s respectively and PPy-CdS multilayer films with bridge configuration were 203 s and 480 s respectively.

A detailed study of the effects of the time-dependent or aging on the characteristic parameters of polypyrrole/p-type Si/Al structure has been presented. The polypyrrole film has been formed on a p-type Si substrate by means of an anodization process. The polypyrrole/p-Si contact has demonstrated clearly rectifying behavior by the current-voltage curves studied at room temperature. The current-voltage (I-V) curves of the diode have been measured immediately, 7, 15, 30, 60 and 90 days after fabrication of the polypyrrole/p-Si contact. It has been seen that the characteristics parameters such as barrier height, ideality factor and series resistance of polypyrrole/p-type Si/Al structure have changed with increasing ageing time. Furthermore, the density distribution of interface states of the device was obtained from the forward bias I-V characteristics. The fact that the diode shows non-ideal I-V behavior with increasing ageing time may be ascribed to a slow replacement of the initial doping agent by oxygen and this process certainly plays a role in the aging of the diode. q

Preparation and basic characterization of polypyrrole-based molecularly imprinted polymer (MIP) for label-free detection of bovine leukemia virus (BLV) glycoprotein gp51 (gp51) is firstly described. Polypyrrole (Ppy) was selected as a matrix for preparation of MIP. Polypyrrole doped by gp51 (gp51/Ppy) was prepared by electrochemical deposition of this polymer on the surface of platinum-black electrode. Then, molecules of gp51 were removed from polymeric backbone and molecularly imprinted polypyrrole (mPpy) was ready for recognition of gp51 in the aqueous solution. Pulsed amperometric detection (PAD) was applied for label-free detection of gp51 in the samples. Anti-gp51 antibodies and secondary antibodies labeled with horseradish peroxidase (HRP) were involved as markers for the control of mPpy preparation procedures. Control experiments were also simultaneously performed by spectrophotometrical detection of HRP activity. Application of anti-gp51 and HRP labelled secondary antibodies confirmed that generation of analytical signal was based on redoping of mPpy by gp51. During our experiments, only few mPpy redoping/dedoping cycles were effective, but generally this method seems to be very effective for the future development of mPpy-based MIPs. Preparation, electrochemical investigation and control procedures are described in the current paper.

The electrochromic (EC) properties of inorganic-organic hybrids of tungsten oxide/polypyrrole (WO3/PPy) thin films were analyzed. Using electrodeposition, WO3 was coated on a conducting glass substrate (Indium doped tin oxide), followed by thermal treatment. In sequence, the PPy thin film was deposited using chemical bath deposition. The structural, morphological, optical, and EC responses of WO3, PPy, and WO3/PPy films are described. The EC properties indicates considerable enhancement in redox kinetics (response time) and coloration efficiency of WO3/PPy films compared with those of the solitary WO3 and PPy films, with a significant increase in EC stability.

Fibres of oil palm empty fruit bunches (OPEFB), a large quantity waste material generated at palm oil
mills, were converted into self-adhesive carbon grains (SACG). KOH treated SACG were added with
0, 5, 10, 15 and 20 wt. % of polypyrrole (PPy) to produce green monoliths (GMs) which were used to
obtain  activated  carbon  monoliths  (ACMs)  electrodes  via  carbonization  (N
2
environment)  and
activation (CO
2
environment) for their application in symmetrical supercapacitors. Various properties
of the electrode materials were examined by thermo-gravimetric analysis, X-ray diffraction and field
emission  scanning  electron  microscopy  techniques.  Electrochemical  performance  of  the  ACMs  as
electrodes was tested with 1 M H
2SO4
as electrolyte using electrochemical impedance spectroscopy,
cyclic voltammetry and galvanostatic charge-discharge techniques. Addition of (15-20) wt. % of PPy
in GMs affects the structure, microstructure and pore structure of the ACMs and consequently leads to
an enhancement of ~ (20-50) F g
-1
, ~ 3-6 Wh kg
-1
and ~ 96-98 W kg
-1
in specific capacitance (C
sp),
specific energy (E) and specific power (P), respectively, with respect to the electrode prepared from
GMs without PPy which offers corresponding values of ~ (2-10) F g
-1
, 2 Wh kg
-1
, and 87 W kg
-1
.

This review focuses on the use of conducting polymer (CP) films in electrochemical affinity sensors and emphasizes innovative designs and unique applications of immunosensors. The review covers some aspects in the application of polypyrrole (Ppy) for the creation of immunosensors. Polypyrrole film fabrication methods like solvent casting, adsorption, and electropolymerization are presented. The focus, is on electrochemically synthesized Ppy as very promising material for the formation of miniaturized electrochemical immunosensors. Polypyrrole films implemented in various capacities in amperometric, conductometric, and potentiometric immunosensor design are reviewed. The acceptance of immobilization and detection approaches used recently in affinity sensors with critical analysis applied in certain techniques is discussed. The biologically active components (BAC) used for the creation of polypyrrole-based immunosensors are described briefly. Some future trends in the development of polypyrrole-based immunosensors are predicted, as well as possible directions discussed.

Heavy metals are toxic substances that pose a real danger to humans and organisms, even at low concentration. Therefore, there is an urgent need to remove heavy metals. Herein, the nanocellulose (NC) was synthesized by the hydrolysis of cellulose using sulfuric acid, and then functionalized using polypyrrole (ppy) through a polymerization reaction to produce polypyrrole/nanocellulose (ppy/NC) nanocomposite. The synthesized nanocomposite was characterized using familiar techniques including XRD, FT-IR, SEM, TEM, and TGA. The obtained results showed a well-constructed nanocomposite with excellent thermal stability in the nano-sized scale. The adsorption experiments showed that the ppy/NC nanocomposite was able to adsorb hexavalent chromium (Cr(VI)). The optimum pH for the removal of the heavy metal was pH 2. The interfering ions showed minor effect on the adsorption of Cr(VI) resulted from the competition between ions for the adsorption sites. The adsorption kinetics were studied usin...

In-situ polymerization of pyrrole was carried out with zirconium oxide, in the presence of oxidizing agent ammonium persulphate, to synthesize polypyrrole/zirconium oxide composites, by chemical oxidation method. The polypyrrole/zirconium oxide composites were synthesized with various compositions viz., 10, 20, 30, 40 and 50 wt. % of zirconium oxide in pyrrole. The powder X-ray diffraction spectrographs suggest that they exhibit semicrystalline behavior. Fourier Transform Infra-Red Spectroscopy shows that, the stretching frequencies are shifted towards higher frequency side. The surface morphologies of these composites studied using Scanning Electron Microscopy indicate that zirconium oxide particles are embedded in the polypyrrole (PPy) chain, to form multiple phases. Thermographs of thermal analysis also imply that the polypyrrole/zirconium oxide composites have stronger stability than PPy. The observation of UV-VIS-NIR spectrum is proof of an interaction between polypyrrole/zirco...

Polyaniline (PANI), polypyrrole (Ppy), and polythiophene (PTh) composite nanoparticles with embedded glucose oxidase (GOx) were formed by enzymatic polymerization of corresponding monomers (aniline, pyrrole, and thiophene). The influence of monomers concentration, the pH of solution, and the ratio of enzyme/substrate on the formation of PANI/GOx, Ppy/GOx, and PTh/GOx composite nanoparticles were spectrophotometrically investigated. The highest formation rate of PANI-, Ppy-, and PTh-based nanoparticles with embedded GOx was observed in the sodium acetate buffer solution, pH 6.0. The increase of optical absorbance at λ max = 440 nm, λ max = 460 nm, and λ max = 450 nm was exploited for the monitoring of PANI/GOx, Ppy/GOx and PTh/GOx formation, respectively. It was determined that the highest polymerization rate of PANI/GOx, Ppy/GOx, and PTh/GOx composite nanoparticles was achieved in solution containing 0.75 mg mL −1 of GOx and 0.05 mol L −1 of glucose. The influence of the enzymatic polymerization duration on the formation of PANI/GOx and Ppy/GOx composite nanoparticles was spectrophotometrically investigated. The most optimal duration for the enzymatic synthesis of PANI/GOx and Ppy/GOx composite nanoparticles was in the range of 48-96 h. It was determined that the diameter of formed PANI/GOx and Ppy/GOx composite nanoparticles depends on the duration of polymerization using dynamic light scattering technique (DLS), and it was in the range of 41-167 nm and 65-122 nm, when polymerization lasted from 16 to 120 h.

The following work reports the evolution of the formation of polypyrrole (PPy) chains and it's intercalation with graphene-carbon nanotubes (G-CNT) nanocomposites. Experiments were carried out to demonstrate the growth of pyrrole through polymerization and its interaction with G-CNT using Cyclic Voltammetry (CV) for 5 – 50 cycles. The interface analysis of the nanocomposite was carried out through SEM. The G-CNT-PPy nanocomposite has shown potential to be used as a supercapacitor which can be further substantiated by CV experiments. 0.89 ml of pyrrole monomer was dispersed in 25 ml of deionized water containing 0.355 g of sodium sulphate. 0.0125 g of CNT and 0.0125 g of graphene was then added to the solution. The solution was further sonicated for 15 minutes at a constant temperature. Cyclic Voltammetry (CV) was used for the synthesis of the nanocomposite film on a graphite rod at a scan rate of 10mV/s in the voltage range of 800 mV – 900 mV. The procedure was repeated for 5, 1...

Substitution of 20% aluminium for nickel in the lattice of nickel hydroxide, prepared by coprecipitation, leads to a hydrotalcite-like compound of formula Ni 0X8 Al 0X2 (OH) 2 (CO 3) 0X1 X0.66 H 2 O. It has been found that the compound has prolonged stability in 6 M KOH solution and can be used as the positive electrode material in rechargeable alkaline batteries. The structure, morphology and composition of the compound have been investigated by X-ray diffraction, scanning electron microscopy and infrared spectroscopy. The electrode comprising the aluminiumsubstituted nickel hydroxide has greater discharge capacity and higher utilization of active material than the b-Ni(OH) 2 electrode. Cyclic voltammetry suggest that the aluminium-substituted nickel hydroxide has better reversibility of the Ni(OH) 2 /NiOOH redox couple and higher oxygen evolution overpotential than b-Ni(OH) 2. The mechanism of the electrode reaction has also been discussed and the proton diffusion coef®cient in the compound has been determined.

In this study, the metabolism of yeast cells (Saccharomyces cerevisiae) was utilized for the synthesis of the conducting polymer-polypyrrole (Ppy).Yeast cells were modified in situ by synthesized Ppy. The Ppy was formed in the cell wall by redox-cycling of [Fe(CN)6] 3-/4-, performed by the yeast cells. Fluorescence microscopy, enzymatic digestions, atomic force microscopy and isotope ratio mass spectroscopy were applied to determine both the polymerization reaction itself and the polymer location in yeast cells. Ppy formation resulted in enhanced resistance to lytic enzymes, significant increase of elasticity and alteration of other mechanical cell wall properties evaluated by AFM. The suggested method of polymer synthesis allows the introduction of polypyrrole structures within cell wall, which is build up from polymers consisting of carbohydrates. This cell wall modification strategy could increase the usefulness of yeast as an alternative energy source in biofuel cells, and in cell based biosensors.

Aqueous zinc-ion batteries (ZIBs) have obtained increasing attention owing to the high safety, material abundance, and environmental benignity. However, the development of cathode materials with high capacity and stable cyclability is still a challenge. Herein, the polypyrrole (PPy)-wrapped V 2 O 5 nanowire (V 2 O 5 /PPy) composite was synthesized by a surface-initiated polymerization strategy, ascribing to the redox reaction between V 2 O 5 and pyrrole. The introduction of PPy on the surface of V 2 O 5 nanowires not only enhanced the electronic conductivity of the active materials but also reduced the V 2 O 5 dissolution. As a result, the V 2 O 5 /PPy composite cathode exhibits a high specific capacity of 466 mAh g −1 at 0.1 A g −1 and a superior cycling stability with 95% capacity retention after 1000 cycles at a high current density of 5 A g −1. The superior electrochemical performance is ascribed to the large ratio of capacitive contribution (92% at 1 mV s −1) and a fast Zn 2+ diffusion rate. This work presents a simple method for fabricating V 2 O 5 /PPy composite toward advanced ZIBs.

In this study electrochemistry of glucose oxidase (GOx) immobilized on a carbon rod electrode modified by gold nanoparticles (Au-NPs) and -conjugated polymer -polypyrrole (Ppy) was studied. Au-NPs facilitated indirect electron transfer via red-ox mediator and showed a positive effect on the amperometric signals of such type electrodes. Several types of electrodes modified by GOx and Au-NPs of different sizes and additionally covered by Ppy layer were investigated. The sensitivity and stability of developed biosensors were evaluated and compared.

A glassy carbon electrode (GCE), modified with graphene (Gr) films, molecularly imprinted (MIP) over-oxidized polypyrrole (OPPy), and electrochemically de posited gold nanoparticles (AuNP) was used for rapid detection of dopamine (DA). The as-prepared electrode (AuNP/Gr/OPPy-MIP/GCE) was characterized by Raman spectroscopy and atomic force microscopy (AFM). Electrochemical determination of DA was conducted via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed that the modified electrodes exhibited high electrocatalytic activity towards the oxidation of DA in 0.1 M phosphate buffer solution (pH 6.9). Linear dependency of electrocatalytic oxidation current on DA concentrations was observed from 0.5 μM to 8 μM and detection limit was estimated to be 0.1 μM (S/N = 3). The developed electrode could serve as a viable platform for further studies on in vivo detection of DA.

In the present study, a sensitive electrochemical aptamer-based biosensing strategy for human non-small cell lung cancer (NSCLC) detection was proposed using nanofiber-modified disposable pencil graphite electrodes (PGEs). The composite nanofiber was comprised of polyacrylonitrile (PAN) and polypyrrole (PPy) polymers, and fabrication of the nanofibers was accomplished using electrospinning process onto PGEs. Development of the nanofibers was confirmed using scanning electron microscopy (SEM). The high-affinity 5′-aminohexyl-linked aptamer was immobilized onto a PAN/PPy composite nanofiber-modified sensor surface via covalent bonding strategy. After incubation with NSCLC living cells (A549 cell line) at 37.5 °C, the recognition between aptamer and target cells was monitored by electrochemical impedance spectroscopy (EIS). The selectivity of the aptasensor was evaluated using nonspecific human cervical cancer cells (HeLa) and a nonspecific aptamer sequence. The proposed electrochemical aptasensor showed high sensitivity toward A549 cells with a detection limit of 1.2 × 103 cells/mL. The results indicate that our label-free electrochemical aptasensor has great potential in the design of aptasensors for the diagnostics of other types of cancer cells with broad detection capability in clinical analysis. Graphical abstract Graphical abstract

Spinel-type binary transition metal oxides of copper and manganese with composition CuxMn3−xO4 (with x=1.0; 1.1; 1.2; 1.3 and 1.4) were prepared in powder forms by thermal decomposition of nitrate precursors at different temperatures. Their structural properties have been examined by X-ray powder diffraction (XRD), oxidation power and X-ray Photoelectron Spectroscopy (XPS) measurements. To study the effects of solid state properties

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Nanocomposites based on two conducting polymers, polyaniline (PANI) and polypyrrole (Ppy), with embedded glucose oxidase (GOx) and 6 nm size gold nanoparticles (AuNPs (6nm)) or gold-nanoclusters formed from chloroaurate ions (AuCl 4 −), were synthesized by enzyme-assisted polymerization. Charge (electron) transfer in systems based on PANI/AuNPs (6nm)-GOx, PANI/AuNPs (AuCl4 −)-GOx, Ppy/AuNPs (6nm)-GOx and Ppy/AuNPs (AuCl4 −)-GOx nanocomposites was investigated. Cyclic voltammetry (CV)-based investigations showed that the reported polymer nanocomposites are able to facilitate electron transfer from enzyme to the graphite rod (GR) electrode. Significantly higher anodic current and well-defined red-ox peaks were observed at a scan rate of 0.10 V s −1. Logarithmic function of anodic current (log I pa), which was determined by CV-based experiments performed with glucose, was proportional to the logarithmic function of a scan rate (log v) in the range of 0.699-2.48 mV s −1 , and it indicates that diffusion-controlled electrochemical processes were limiting the kinetics of the analytical signal. The most efficient nanocomposite structure for the design of the reported glucose biosensor was based on two-day formed Ppy/AuNPs (AuCl4 −)-GOx nanocomposites. GR/Ppy/AuNPs (AuCl4 −)-GOx was characterized by the linear dependence of the analytical signal on glucose concentration in the range from 0.1 to 0.70 mmol L −1 , the sensitivity of 4.31 mA mM cm −2 , the limit of detection of 0.10 mmol L −1 and the half-life period of 19 days.

This study is purposed with the preparation of polyacrylamide/Polypyrrole hydrogel composite, in which the hydrogel of crosslinked polyacrylamide is a matrix and Polypyrrole is an electro-conducting component. The effects of synthesis conditions on the structure of the composite systems, their ability to swell in water, and mechanical characteristics are studied. The proposed synthesis procedure allows production of a bulk electro-conducting phase of Polypyrrole in the hydrogel matrix. The effect of crosslink density of hydrogel on the character of Polypyrrole distribution in the matrix is studied. The above composites combine the electrical characteristics of Polypyrrole with high elasticity and the ability to repeatedly swell the cross-linked poly (acrylamide).

Polypyrrole (Ppy) has been shown to be a superior matrix for fluorescence detection based immunosensors: (i) the fluorescence of polypyrrole and polypyrrole modified by entrapped proteins was almost not detectable when this polymer was excited by near UV 325 nm light; (ii) polypyrrole quenched the fluorescence of such fluorescence agents as fluoresceine 5(6)-isothiocyanate, rhodamine B and enzyme-horseradish peroxidase (HRP) by almost 100% if they were deposited in the solution as a drop at the Ppy surface followed by evaporation of the solvent. According to our knowledge, this work is first application of Ppy in the design of a fluorescence-based immunosensor, where low Ppy fluorescence background and Ppy induced fluorescence quenching were exploited. These sensors were devoted to the detection of antibodies against bovine leukemia virus (BLV) protein gp51 (anti-gp51-Ab). A biological recognition system of this fluorescence immunosensor model was based on polypyrrole with entrapped BLV proteins gp51 (gp51/Ppy). This gp51/Ppy layer was applied for the detection of anti-gp51-Ab. Secondary antibodies against anti-gp51-Ab labeled with HRP (Ab*) were applied as fluorescence-detectable labels that are able to recognize specifically and interact with the complex of gp51 proteins and anti-gp51-Ab antibodies (gp51/anti-gp51-Ab). It was demonstrated that fluorescence of non-specifically adsorbed Ab* was almost completely quenched by the Ppy substrate. In addition, enzymatic activity of HRP was exploited as a traditional reference method for verification of the formation of the immune complex gp51/anti-gp51-Ab/Ab*.

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Transition metal dichalcogenides (TMDs) like Molybdenum disulfide (MoS 2) are confessed as an effective energy storage materials due to their 2D structure analogues to graphene. Robust 3D architectures of graphene oxide-polypyrrole (GO-PPy) and molybdenum disulfide-polypyrrole (MoS 2-PPy) were fabricated by facile, one pot chronoamperometry method to achieve scalable, conductive additive free and binder free supercapacitor electrodes. The electrodeposited GO-PPy and MoS 2-PPy electrodes exhibit the specific capacitance of 271 F g −1 and 130 F g −1 respectively at a current density of 1 A g −1. The introduction of reduced graphene oxide (rGO) in PPy matrix offered high capacitance, whereas graphene analogue MoS 2 improved the structural stability. Pronounced cycling stability (>2000 cycles) and noteworthy capacitive retentions were also displayed by these composites. MoS 2-PPy and GO-PPy retain 82 and 64% of its initial capacitance respectively. These findings are backed up by the correlation of structure and electrochemical performance of GO-PPy and MoS 2-PPy. Highlights  3D architectures of binary electrodes are fabricated by electrodeposition.  Integration of graphene oxide in polypyrrole matrix offers high capacitance.  Molybdenum disulfide enhances the structural stability and high capacitance retention.  The advantages of individual components are tapped successfully in the composites.

The conventional electromagnetic interference (EMI) shielding materials are being gradually replaced by a new generation of supported conducting polymer composites (CPC) films due to their many advantages. This work presents a contribution on the effects of silane surface–modified flexible polypyrrole-silver nanocomposite films on the electromagnetic interference shielding effectiveness (EMI-SE). Thus, the UV-polymerization was used to in-situ deposit the PPy-Ag on the biaxial oriented polyethylene terephthalate (BOPET) flexible substrates whose surfaces were treated by 3-aminopropyltrimethoxysilane (APTMS). X-ray Photoelectron Spectroscopy (XPS) analyzes confirmed the APTMS grafting procedure. Structural, morphological, thermal, and electrical characteristics of the prepared films were correlated to the effect of substrate surface treatment. Thereafter, EMI-SE measurements of the elaborated films were carried out as per ASTM D4935 standard for a wide frequency band extending from 5...

In the present work, a novel biosensor (GCE/RGO/PPy/NR) based on the nanocomposite of reduced graphene oxide (RGO), polypyrrole (PPy) immobilized by nitrate reductase (NR) was developed on a glassy carbon electrode (GCE). The conductive nanocomposite (RGO/PPy) was synthesized by in situ oxidative polymerization of pyrrole in the presence of RGO in acidic medium. A facile and green path was employed to synthesize RGO from graphene oxide (GO). This was performed by a novel route using Abelmoschus esculentus vegetable extract as a stabilizing and reducing agent for GO. The composite of reduced graphene oxide and polypyrrole (RGO/PPy) was deposited onto GCE with subsequent deposition of NR enzyme on the GCE/ RGO/PPy to develop GCE/RGO/PPy/NR biosensor. The surface morphology and structural features of the composites were studied by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical behavior and electrocatalytic activity of the biosensor were examined by cyclic voltammetry at different scan rates (20-100 mV s −1) in the synthetic nitrate solution. The developed bio-anode achieved a maximum current density of 4.24 mA cm −2 at a scan rate of 100 mV s −1 for 10 mM sodium nitrate solution.

Electrochemical behavior of the electroactive polymeric hydrogels based on polyaniline (PANI) and polypyrrole (PPy) was studied by applying 50,000 galvanostatic charge–discharge cycles. Influence of repetitive electrochemical charge–discharge on the structure of hydrogels was followed by SEM, WAXD and FTIR techniques. The PPy-based hydrogel was found to be more stable demonstrating capacitance retention of 73% and 45% after 5000 and 50,000 charge–discharge cycles, respectively. The decrease in electrochemical performance of PPy can be attributed mainly to overoxidation of the conducting polymer, associated with the formation of hydroxyl and carbonyl groups connected to the pyrrole rings. In the case of PANI, crosslinking of the conducting polymer during electrochemical cycling can be proposed. This leads to micro-syneresis inside the hydrogel and to the formation of porous structure at the initial stages of cycling. During long-term experiment, the crosslinking leads to the formatio...

In-situ polymerization of pyrrole (Py) was carried out with Zinc Tungstate (ceramic) in the presence of oxidizing agent ammonium persulphate to synthesize polypyrrole (PPy)/Zinc Tungstate (ZnWO4) by chemical oxidation method. The PPy/ ZnWO4 composites were synthesized with various compositions viz., 10, 20, 30, 40 and 50 wt. % of NaVO3 in Py. The surface morphologies of these composites were analyzed using Scanning Electron Microscopy (SEM), show that ZnWO4 particles are embedded in PPy chain to form multiple phases. The Fourier Transform Infra-Red Spectroscopy (FTIR) reveals the stretching frequencies were shifted towards higher frequency side. The powder X-ray diffraction (XRD) spectrograph, suggests that they exhibit semi-crystalline behavior. Thermal analysis (TG/DTA) studies/testing were done and reported. The frequency dependent A.C. conductivity reveals that, the ZnWO4 concentration in PPy is responsible for the variation of conductivity of the composites. Values of the condu...

Duplex coating consisting of an inner cerium-based layer and polypyrrole (PPy) film topcoat was electrodeposited onto AISI 304 stainless steel. The cerium-based coating was electrodeposited in solutions containing cerium nitrate at 50 ºC. The polymeric outer layer was electropolymerized in the presence of sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The electrosynthesis was done under potentiostat conditions. The coatings were characterized by scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDX). The morphology of the doublelayered cerium polypyrrole film shows a granular structure with the presence of agglomerates of small grains. The anticorrosive performance of the coatings was evaluated in sodium chloride solution by linear polarization, open circuit measurements, and electrochemical impedance spectroscopy (EIS). Single films, cerium layer and PPy coating, and the duplex film all reduce the corrosion rate of AISI 304 stainless steel in NaCl solution. The duplex coating presents an improved corrosion resistance concerning the single films. The combination of the characteristics of the single layers is responsible for the superior corrosion protection efficiency of the double-layered cerium polypyrrole coating.

A novel model potential is developed for simulating oxidised oligopyrroles in condensed phases. The force field is a coarse grained model that represents the pyrrole monomers as planar rigid bodies with fixed charge and dipole moment and the chlorine dopants as point atomic charges. The analytic function contains 17 adjustable parameters that are initially fitted on a database of small structures calculated within all-electron density functional theory. A subsequent potential function refinement is pursued with a battery of condensed phase isothermal-isobaric Metropolis Monte Carlo in-silico simulations at ambient conditions with the goal of implementing a hybrid parametrization protocol enabling agreement with experimentally known thermodynamic properties of oxidised polypyrrole. The condensed system is composed of oligomers containing 12 monomers with a 1:3 dopant-to-monomer concentration. The final set of force field optimised parameters yields an equilibrium density of the condensed system at ambient conditions in excellent agreement with oxidised polypyrrole samples synthesised in wet-laboratories.