Electropolymerization Of Pyrrole Research Articles

Introduction of electropolymerization of pyrrole as a coating method for stir bar sorptive extraction of estradiol followed by gas chromatography

In this study, fabrication of a stir bar sorbent is presented by electropolymerization of pyrrole via cyclic voltametry for the first time. The fabricated stir bar was applied as an efficient sorbent for extraction and pre-concentration of trace amounts of estradiol in urine samples through stir bar sorptive extraction (SBSE) method followed by gas chromatography-flame ionization detector. For this purpose, first the surface of stainless steel rod was modified by hyroxide functional group. Then electropolymerization of pyrrole monomers took place on the surface of functionalized steel rod under the optimized conditions including pyrrole concentration of 0.03 mol L−1, equal concentration ratio of pyrrole to sodium dodecyl sulfate, 10 cycles of cyclic voltammetry and potential scan rate of 10 mV s−1. Characterization of the produced sorbent was confirmed by scanning electron microscope imaging and energy-dispersive X-ray and infrared spectroscopy. Evantually, under the optimized conditions, the stir bar sorbent was used for extraction of estradiol from human urine samples. The presented SBSE method showed a good linearity range of 50–700 ng mL−1 with coefficient of determination 0.9910, limit of detection 10 ng mL−1 and theoretical limit of quantification 33 ng mL−1. Moreover, better enrichment factor (87) and extraction recovery (43%) were obtained using the fabricated stir bar compared with two commercial stir bars for estradiol. The intra- and inter-bar relative recoveries were obtained 92.0% and their coefficient of variations were less than 5.4%.

Molecularly imprinted polymer SPE sensor for analysis of CA-125 on serum

Considering the high incidence level and mortality rate of ovarian cancer, particularly among the European female population, the carbohydrate antigen 125 (CA-125) was selected as the protein target for this study for the development of a MIP-based biosensor.This work presents the development of molecular imprinting polymers (MIPs) on gold electrode surface for CA-125 biomarker recognition. The preparation of the CA-125 imprinting was obtained by electropolymerization of pyrrole (Py) monomer in a gold electrode using cyclic voltammetry (CV) in order to obtain highly selective materials with great molecular recognition capability. The quantification of CA-125 biomarker was made through the comparison of two methods: electrochemical (square wave voltammetry -SWV) and optical transduction (surface plasmon resonance -SPR). SWV has been widely used in biological molecules analysis since it is a fast and sensitive technique. In turn, SPR is a non-destructive optical technique that provides high-quality analytical data of CA-125 biomarker interactions with MIP.Several analytical parameters, such as sensitivity, linear response interval, and detection limit were determined to proceed to the performance evaluation of the electrochemical and optical transduction used in the development of the CA-125 biosensor.The biosensor based in the electrochemical transduction was the one that presented the best analytical parameters, yielding a good selectivity and a detection limit (LOD) of 0.01 U/mL, providing a linear concentration range between 0.01 and 500 U/mL. This electrochemical biosensor was selected for the study and it was successfully applied in the CA-125 analysis in artificial serum samples with recovery rates ranging from 91 to 105% with an average relative error of 5.8%.

Optimization of Pyrrole Electropolymerization on a Steel Gauze Electrode Using the Cyclic Voltammetry Method

Study on pyrrole electropolymerization is the preliminary step in synthesizing polypyrrole membranes, which can be used for various purposes in biosensor. In this work, electropolymerization process and electrochemical analysis of polypyrrole as an electroactive polymer have been studied by cyclic voltammetry. Pyrrole was electropolymerized to form polypyrrole in an aqueous potassium chloride solution at different pHs using phosphate buffer. The results showed that a potential range of 0-1200 mV is suitable for polypyrrole electropolymerization using the Ag|AgCl electrode as the reference. The formation of polypyrrole is stable at a scan rate of 100 mV/s. In addition, the optimized pyrrole electropolymerization was obtained using 0.1 M pyrrole and phosphate buffer at pH of 2-6. Taken together, this study can be used as a reference for the synthesis of other conducting polymers.

Influence of the electrolytic medium on the performance and stability of functionalized graphene-polypyrrole nanocomposites as materials for supercapacitors

Abstract Nanocomposites made of functionalized graphene with polypyrrole were synthesized in two steps by first incorporating pyridine-pyridazine functions on graphene surface through cycloaddition followed by electropolymerization of pyrrole in acetonitrile. The specific capacitance of the material was measured by galvanic charge-discharge cycles and the stability upon cycling investigated in various electrolytic media (acetonitrile, ionic liquid, acidic and neutral water) in comparison with non-functionalized graphene with or without polypyrrole. While acetonitrile reveals pure capacitive behavior for all materials investigated, acidic water is the medium where the capacitance values are the highest and surprisingly where nanocomposites with polypyrrole show a better capacitance retention upon cycling than graphene alone. A positive impact of graphene functionalization prior to electropolymerization was demonstrated in all electrolytic media (capacitance losses limited to less than 8% after 1500 cycles in all media but neutral water), highlighting the interest of interface control in this kind of nanocomposites.

Sensitive and Selective Electrochemical Sensor Based on Molecularly Imprinted Polypyrrole Hybrid Nanocomposites for Tetrabromobisphenol A Detection

A sensitive and selective electrochemical sensor based on electropolymerized molecularly imprinted polypyrrole and gold nanoparticles–multiwalled carbon nanotubes (AuNPs–MWCNTs) hybrid nanocomposites was developed for the determination of tetrabromobisphenol A (TBBPA). A glassy carbon electrode (GCE) was modified with MWCNTs, and the AuNPs–MWCNTs/GCE was prepared by an electrodeposition method in HAuCl4 solution. The AuNPs–MWCNTs nanocomposite showed high electrocatalytic activity, good conductivity, and sufficient reactive sites for the direct electro-oxidation of TBBPA. The molecularly imprinted polymers (MIPs) as recognition elements were synthesized through in situ electro-polymerization of pyrrole as functional monomers in the presence of the TBBPA template molecules. Under the optimal conditions, the developed sensor exhibited good selectivity towards TBBPA compared with structural analogs, high sensitivity, and excellent producibility. The electrochemical responses of the sensor toward TBBPA were obtained in the linear range from 0.5 nM to 1 μM with a limit of detection equal to 0.24 nM at a signal-to-noise ratio of 3.

Ethanol bioelectrooxidation in a robust poly(methylene green-pyrrole)- mediated enzymatic biofuel cell

We prepared robust bioanodes by immobilizing the alcohol dehydrogenase (ADH) enzyme onto a one-pot electropolymerized film consisting of methylene green and pyrrole. The enzymatic film containing immobilized ADH furnished power densities as high as 183±10μWcm−2; addition of carbon nanotubes (MWCNTs) increased the bioanode power density to 275±12μWcm−2. The bioanode was very stable, with a mean decay of 36% of its initial power density after 20weeks of storage. Long-term ethanol electrolysis (12h) followed by HPLC-UV/RID confirmed that the system was highly selective and generated a two-electron product. MWNCT introduction provided five times higher acetaldehyde production. Compared to literature data, results were promising and showed that the system can be used to construct biofuel cells. In addition, the film obtained by simultaneous methylene green and pyrrole electropolymerization afforded interesting results and can be applied in other systems, such as biosensors.

Probe and analogue: Double roles of thionine for aloe-emodin selective and sensitive ratiometric detection

Molecular imprinted polymer (MIP) has been employed for electrochemical sensor preparation with good selectivity. However, to restrict the non-specific adsorption, the conductivity of MIP is usually unsatisfying, which limits its sensitivity for template detection. To achieve both of selectivity and sensitivity, a MIP electrochemical sensor was designed and fabricated by the electropolymerization of pyrrole in the presence of aloe-emodin (AE, template molecule) on carbon nanoparticles modified electrode in this work. Thionine (TH), being added in solution in advance, played double roles for AE recognition and detection. As an analogue of AE, TH was adsorbed into imprinted cavities and then was replaced by AE, indicating the good selectivity of the sensor. This replacement of TH by AE was also demonstrated by the result of computational simulation. As an electro-active probe, the peak current of TH decreased and peak current of AE increased based on the replacement of TH by AE. A current ratiometric signal defined as |ΔiAE|/|ΔiTH| was used for AE sensitive detection. Thus, the replacements of TH by AE demonstrated that the sensor possessed high sensitivity and good selectivity. A linear range of 1.0 × 10−7 -1.0 × 10-4 mol/L for AE detection was obtained with a limit of detection of 7.5 × 10-8 mol/L. And the sensor has been applied to analyze AE in real samples with satisfactory results. The simple, smart, and effective strategy presented in this work can be further used to prepare electrochemical sensors for other compounds selective recognition and sensitive detection.

A dual template imprinted polymer modified electrochemical sensor based on Cu metal organic framework/mesoporous carbon for highly sensitive and selective recognition of rifampicin and isoniazid

A highly sensitive and selective doubly imprinted polymer modified electrochemical sensor based on copper metal organic framework/mesoporous carbon (Cu-MOF/MC) composite was developed for simultaneous determination of Rifampicin (RIF) and Isoniazid (INZ). The molecularly imprinted polymer (MIP) film was formed on the surface of Cu-MOF/MC modified glassy carbon electrode (GCE) by incorporating RIF and INZ as template molecules during electropolymerization of pyrrole, followed by removal of both the template molecules. During this process of sensor fabrication, large numbers of complementary binding sites for template molecules are created on the surface of MIP sensor due to high surface area offered by Cu-MOF/MC composite. Various parameters influencing the performance of MIP sensor such as number of electropolymerization cycles and template: monomer ratio were optimized during the study. Based on the optimized parameters, the electrochemical response of Cu-MOF/MC/MIP/GCE towards determination of RIF and INZ was studied in a wide linear working range of 0.08 μM to 85 μM employing adsorptive stripping differential pulse voltammetry in aqueous as well as real samples. The limit of detection was found to be 0.28 nM and 0.37 nM for RIF and INZ respectively. In addition, the MIP sensor showed good stability, acceptable reproducibility and high selectivity for RIF and INZ over other common interferents. Moreover, the developed sensor was successfully applied for simultaneous determination of RIF and INZ in pharmaceutical formulations, blood serum and urine samples with satisfactory recoveries.

Using Electropolymerization-based Doping for the Electro-addressable Functionalization of a Multi-electrode Array Probe for Nucleic Acid Detection.

Even though large number of individually addressable electrodes can be effectively assembled in a small area, electrochemical detection methods have a relatively limited ability to detect multiple analytes compared to microdialysis probes and other analytic techniques. Here, we report a facile method for the electro-addressable functionalization of a probe comprising of closely spaced three individually addressable carbon fiber electrodes (CFEs) for the detection of nucleic acids. First, a multi electrode array probe comprising three adjacent CFEs was fabricated through pulling a three-barrel glass capillary with a single carbon fiber in each barrel. Second, electropolymerization based doping was used for the electro-addressable functionalization of the multi-electrode array probe. To demonstrate that the current strategy works, anti-miR-34a was electrografted on only one of three electrodes by the electropolymerization of pyrrole on a specific electrode. A second electrode was coated only with polypyrrole (PPy) and the third was left unmodified. The results demonstrate that the present strategy has great potential for constructing multiplex nucleic acid micro/nano biosensors for local and in situ detection of multiple nucleic acid molecules, such as miRNAs at a time.

Studies on the formation and properties of polypyrrole doped with ionised β-cyclodextrins: influence of the anionic pendants

Polypyrrole films doped with sulfonated β-cyclodextrin (PPy/sβ-CD) and carboxymethyl β-cyclodextrin (PPy/CMβ-CD) were formed on electropolymerisation of pyrrole in a solution of the cyclodextrin sodium salts. Lower rates of electropolymerisation were evident with the carboxymethyl β-CD and this was attributed to protonation of the carboxylate groups due to an increase in the interfacial pH at the electrode–solution interface. The PPy/sβ-CD and PPy/CMβ-CD films showed cation exchange behaviour with the ingress of Na+ and its associated water molecules on reduction. The PPy/CMβ-CD film showed less electroactive behaviour which may be related to the lower number of anionic pendants on the CMβ-CD or to the possible precipitation of the less soluble neutral CD which arises due to the protonation of the carboxylate groups. The PPy/sβ-CD showed a high capacitance of 6.0 mF cm−2 corresponding to a specific capacitance of 71 F g−1 over a wide potential range extending from − 0.60 to 0.60 V vs SCE. Over-oxidation was observed at relatively low potentials, at about 0.60 V vs SCE. A diffusion coefficient of 6.47 × 10−6 cm2 s−1 and a rate constant of 3.73 × 10−2 cm s−1 were obtained for the ferricyanide redox couple at the PPy/sβ-CD, indicating little or no inhibition of the ferricyanide redox reaction.

Efficiency of Pyrrole Electropolymerization under Various Conditions

The electrooxidative polymerization of pyrrole on the surface of a glassy carbon electrode was studied, while varying the solvent, the type and concentration of supporting electrolyte, redox mediator addition to the polymerization medium, and hydrodynamic conditions. The efficiency of polymerization was determined as the ratio of the charge of the redox response of the polymer film under the standard conditions to the total charge of film formation in the monomer solution. The above factors were varied to determine the conditions that allow minimization of the ratio in order to obtain the highest yield of the polymer product. This was achieved by using a combination of a redox mediator addition with active stirring of solution.

Salicylate release from a polypyrrole matrix

Salicylate release from a microstructured polypyrrole coating with a large surface area was investigated. The drug was incorporated as a dopant in the polymer matrix via electropolymerization of pyrrole in a simple one-step process. The influence of several parameters such as applied potential and hydrodynamic conditions on the releasing behavior was studied. Once the drug has been delivered from the polymeric matrix, the electrode can be reloaded with salicylate for later release. The amount of eluted salicylate was effective in inhibiting albumin denaturation which is associated with antiinflammatory effects.

Walnut-like Transition Metal Carbides with Three-Dimensional Networks by a Versatile Electropolymerization-Assisted Method for Efficient Hydrogen Evolution.

Mo2C@NPC (N,P-doped carbon) electrocatalysts are developed on carbon cloth (CC) as binder-free cathodes for efficient hydrogen evolution through a facile route of electropolymerization followed by pyrolysis. Electropolymerization of pyrrole to form polypyrrole occurs with the homogeneous incorporation of PMo12, driven by Coulombic force between the positively charged polymer backbone and PMo12 anions. This electrochemical synthesis is easily scaled up, requiring neither complex instrumentation nor an intentionally added electrolyte (PMo12 also acts as an electrolyte). After pyrolysis, the resultant Mo2C@NPC/CC electrode exhibits a unique interconnected walnut-like porous structure, which ensures strong adhesion between the active material and the substrate and favors electrolyte penetration into the electrocatalyst. This method is effective with other monomers such as aniline and is readily extended to fabricate other metal carbide electrodes such as WC@NPC/CC. These carbide electrodes exhibit high catalytic performance for hydrogen production, for example, WC@NPC/CC can deliver an unprecedented current density of 600 mA cm-2 at an overpotential of only 200 mV either in an acidic or an alkaline solution. Considering the simplicity, scalability, and versatility of the synthetic method, the unique electrode structure, and the excellent catalysis performance, this study opens up new avenues for the design of various novel binder-free metal carbide cathodes based on electropolymerization.

In-situ odd random phase electrochemical impedance spectroscopy study on the electropolymerization of pyrrole on iron in the presence of sodium salicylate – The influence of the monomer concentration

In this work, the potentiostatic electropolymerization of polypyrrole (PPy) on iron in aqueous solution of sodium salicylate and pyrrole is studied in situ by odd random phase electrochemical impedance spectroscopy (ORP-EIS). The influence of the pyrrole concentration on the electrosynthesis process is investigated. The ORP-EIS technique ensures a reliable analysis of the PPy electrosynthesis on iron by means of an advanced data analysis of the non-linear and non-stationary behaviour and the signal-to-noise ratio of the system. Additionally, the structure and the chemical nature of the PPy film on iron are studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and glow discharge optical emission spectroscopy (GDOES). The results of the characterization confirm the presence of the passivation layer at the PPy/iron interface formed prior to the polymer deposition. The modelling of the impedance evolution over time provides the quantitative analysis of the electropolymerization of PPy on iron. The results show that the electrosynthesis of pyrrole on oxidizable iron in the presence of sodium salicylate is a complex process, which includes not only the pyrrole oxidation reactions but also reactions such as the oxidation/reduction of the iron surface and/or reactions between the iron, formed interlayer and polypyrrole.

Selective and sensitive electrochemical sensing of gastrodin based on nickel foam modified with reduced graphene oxide/silver nanoparticles complex-encapsulated molecularly imprinted polymers

In this work, a facile one-step electrochemical coreduction method was developed to synthesize reduced graphene oxide (rGO) and silver nanoparticles (AgNPs) onto the surface of nickel foam (NF). Using graphene oxide and Ag(NH3)2OH as precursors, rGO and AgNPs were co-deposited on NF surface. The rGO-AgNPs modified NF was covered with molecularly imprinted polymers (MIPs) through in-situ electro-polymerization of pyrrole in the presence of gastrodin (GAS). After the elution of templated GAS molecules, poly(pyrrole)-based MIPs were covered on the surface of rGO-AgNPs modified NF to form MIPs/rGO-AgNPs/NF system. The system as a novel working electrode exhibited sensitive and selective electrochemical signal responses towards GAS. Under optimal conditions, MIPs/rGO-AgNPs/NF had a nearly linear relationship between the oxidation current peak intensities and GAS concentration in the range of 0.01–1 μM (R2 = 0.9919), with a low limit of detection of 1 nM. MIPs/rGO-AgNPs/NF was used as a novel MIPs electrochemical GAS sensor that showed an excellent capability of GAS detection, over potential interferents. In human serum samples, the detection of GAS based on this sensor had high detection stability and recovery. Experimental results demonstrated a high feasibility of MIPs/rGO-AgNPs/NF for GAS detection in real samples.

Label-free electrochemical sensor based on spore-imprinted polymer for Bacillus cereus spore detection

Herein, we report a simple, cost-effective, selective, and rapid electrochemical sensor for Bacillus cereus spore detection, used as simulant for Bacillus anthracis spores. The sensor was developed using carbon paste electrode functionalized with imprinted polymer, fabricated by pyrrole electropolymerization in presence of a known amount of spores as template onto the surface of working electrochemical sensor. The measurement encompasses the cyclic voltammetry as technique and [Fe(CN)6]3−/4− as redox probe for electrochemical measurements. The effect of ultrasonication and surfactants with positive, negative and neutral charge on template removal was investigated. Several parameters including the concentration of monomer, the number of scans, the type and the concentration of removal agent, and the incubation time were optimized. The carbon paste electrode modified with spore-imprinted polymer (CPE/SIP) exhibited a good affinity and selectivity towards Bacillus cereus spores. The sensitivity of the CPE/SIP was investigated in the spore concentration ranging from 102 up to 105 CFU/mL, demonstrating the suitability of this sensor for fast and effective measurements of Bacillus cereus spores.

Multidimensional Conductive Nanofilm-Based Flexible Aptasensor for Ultrasensitive and Selective HBsAg Detection.

Hepatitis B virus (HBV) infection is a major worldwide health issue causing serious liver diseases, including liver cirrhosis and hepatocellular carcinoma. Monitoring the serum hepatitis B surface antigen (HBsAg) level is pivotal to the diagnosis of HBV infection. In this study, we describe multidimensional conductive nanofilm (MCNF)-based field-effect transistor (FET) aptasensor for HBsAg detection. The MCNF, composed of vertically oriented carboxylic polypyrrole nanowires (CPPyNW) and graphene layer, is formed using electropolymerization of pyrrole on the graphene surface and following acid treatment. The amine-functionalized HBsAg-binding aptamers are then immobilized on the CPPyNW surface through covalent bonding formation (i.e., amide group). The prepared aptasensor presents highly sensitive to HBsAg as low as 10 aM among interfering biomolecules with various deformations. Moreover, the MCNF-based aptasensor has great potential for practical application in the noninvasive real-time diagnosis because of its improved sensing ability to the human serum and artificial saliva.

A novel and sensitive electrogenerated chemiluminescence biosensor for detection of p16INK4a gene based on the functional paste-like nanofibers composites-modified screen-printed carbon electrode

In this work, we offered a novel and sensitive electrogenerated chemiluminescence (ECL) biosensing system for detection of p16INK4a gene using the functional paste-like nanofibers composites-modified screen-printed carbon electrode (SPCE). The paste-like nanofibers composites (PG/GR/CS) which were comprised of the electrospun nanofibers (PG, the graphene (GR) doped polycaprolactam 6 (PA6) were prepared via one-step electrospinning), graphene (GR) and chitosan (CS) were served as the nanosized backbones for pyrrole (Py) electropolymerization. The functional paste-like nanofibers composites (PG/GR/CS/PPy) used as a substrate for dsDNA (hybridization reaction of ssDNA1, p16INK4a gene and the Ru(bpy)32+/silver nanoparticles (AgNPs) doped gold (Au) core-shell luminescent composite nanoparticles labeled ssDNA2 (RuAg@AuNPs-ssDNA2)) immobilization. Under optimal conditions, a linear relationship between ECL intensity and p16INK4a gene concentration was found in a range of 0.1 pM–1 nM with the detection limit of 0.05 pM (S/N = 3). This ECL biosensor based on the PG/GR/CS/PPy-modified SPCE demonstrated excellent electrochemical performance for the detection of p16INK4a gene and this platform can be used for the determination of various analytes.

Modifying Current Collectors to Produce High Volumetric Energy Density and Power Density Storage Devices.

We develop zirconium-templated NiO/NiOOH nanosheets on nickel foam and polypyrrole-embedded in exfoliated carbon fiber cloth as complementary electrodes for an asymmetric battery-type supercapacitor device. We achieve high volumetric energy and power density by the modification of commercially available current collectors (CCs). The modified CCs provide the source of active material, actively participate in the charge storage process, provide a larger surface area for active material loading, need no additional binders or conductive additives, and retain the ability to act as the CC. Nickel foam (NF) CCs are modified by use of a soft-templating/solvothermal treatment to generate NiO/NiOOH nanosheets, where the NF is the source of Ni for the synthesis. Carbon-fiber cloth (CFC) CCs are modified by an electrochemical oxidation/reduction process to generate exfoliated core-shell structures (ECFC). Electropolymerization of pyrrole into the shell structure produces polypyrrole embedded in exfoliated core-shell material (PPy@rECFC). Battery-type supercapacitor devices are produced with NiO/NiOOH@NF and PPy@rECFC as positive and negative electrodes, respectively, to demonstrate the utility of this approach. Volumetric energy densities for the full-cell device are in the range of 2.60-4.12 mWh cm-3 with corresponding power densities in the range of 9.17-425.58 mW cm-3. This is comparable to thin-film lithium-ion batteries (0.3-10 mWh cm-3) and better than some commercial supercapacitors (<1 mWh cm-3).1 The energy and power density is impressive considering that it was calculated using the entire cell volume (active materials, separator, and both CCs). The full-cell device is highly stable, retaining 96% and 88% of capacity after 2000 and 5000 cycles, respectively. These results demonstrate the utility of directly modifying the CCs and suggest a new method to produce high volumetric energy density and power density storage devices.

Solid-phase microextraction of heavy metals in natural water with a polypyrrole/carbon nanotube/1, 10–phenanthroline composite sorbent material

A simple and sensitive method for simultaneous microextraction and determination of heavy metals using a new direct immersion solid-phase microextraction (DI–SPME) sorbent material combined with inductively coupled plasma mass spectrometry (ICP–MS) was investigated. In this method, sorbent coating composites were prepared by simultaneous electropolymerization of pyrrole on pencil lead in the presence of carbon nanotubes (CNTs) and different metal chelating ligands. Among the coatings evaluated, a polypyrrole coating with entrapped CNTs and the chelator 1, 10 phenanthroline allowed the determination of silver, cadmium, cobalt, iron, nickel, lead, and zinc. Parameters influencing microextraction efficiency including pH, extraction time, and desorption time were optimized. The linear dynamic ranges were 1–1000 μg L−1 for Ag, 1–750 μg L−1 for Cd, Pb, and Zn, and 1–500 μg L−1 for Co, Fe, and Ni with limits of detection of 0.012–0.163 μg L−1 and limits of quantification of 0.039–0.542 μg L−1. The relative standard deviations (RSDs, n = 5) ranged from 1.85% to 5.01%. The effect of inorganic interferences on the determination of the heavy metals also was examined and finally, the method was successfully applied for the determination of heavy metals in real water samples.