Conducting polymer composites of polyvinylferrocene and polypyrrole (PVF/PPy) were synthesized ch... more Conducting polymer composites of polyvinylferrocene and polypyrrole (PVF/PPy) were synthesized chemically by the in situ polymerization of pyrrole in the presence of PVF using FeCl3 as oxidant. Acetic (CH3COOH) and boric (H3BO3) acids were used as the synthesis medium. Effects of the synthesis medium on the properties of the PVF/PPy composite were investigated. The PVF/PPy composites and homopolymers were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and magnetic susceptibility techniques. Conductivity measurements were performed using the four‐probe technique. We found that the conductivities of PVF/PPy‐H3BO3 (1.19 S cm−1) and PVF/PPy‐CH3COOH (4.5×10−1 S cm−1) increased relative to those of the homopolymers of PPy‐H3BO3 (2.1×10−2 S cm−1) and PPy‐CH3COOH (1.2×10−2 S cm−1) due to the interaction of PVF with the pyrrole moiety. The stability of all homopolymers and composites were investigated by thermogravimetric analysis and by conductivity measurements during heating‐cooling cycles. There was a small drop in conductivity caused by the annealing of PVF/PPy composites at 70°C. The conductivity of all samples increased with temperature and exhibited stable electrical behavior with increasing temperature. TGA analysis of samples showed that the composites were more stable than the homopolymers or PVF separately. The magnetic susceptibility values of samples were negative, except for PVF/PPy‐H3BO3. Morphology changes of the composites investigated by scanning electron microscopy (SEM), attributed to synthesis conditions, have a significant effect on their conductivity.
... a Department of Chemistry, Selçuk University, Konya 42075, Turkey. b Department of Chemical E... more ... a Department of Chemistry, Selçuk University, Konya 42075, Turkey. b Department of Chemical Engineering, Selçuk University, Konya 42075, Turkey. Received 8 April 2011; revised 24 June 2011; accepted 24 June 2011. Available online 2 July 2011. Abstract. ...
Coimmobilization of beta-galactosidase and glucose oxidase in a redox polymer, polyvinylferroceni... more Coimmobilization of beta-galactosidase and glucose oxidase in a redox polymer, polyvinylferrocenium perchlorate (PVF+ ClO4-), led to the development of an enzyme electrode for the determination of lactose. The amperometric response of the electrode was measured at +0.70 V vs. SCE, which was due to the electrooxidation of enzymatically produced H2O2. The effects of the substrate and buffer concentrations as well as the pH on the electrode response were elucidated.
A simple method of enzyme immobilization was investigated, which is useful for development of enz... more A simple method of enzyme immobilization was investigated, which is useful for development of enzyme electrodes based on polyvinylferrocenium perchlorate coated Pt electrode surface. Enzymes were incorporated into the polymer matrix via ion exchange process by immersing polyvinylferrocenium perchlorate coated Pt electrode in enzyme solution for several times. Choline and acetylcholine enzyme electrodes were developed by co-immobilizing choline oxidase and acetylcholinesterase in polyvinylferrocenium perchlorate matrix coated on a Pt electrode surface. The amperometric responses of the enzyme electrodes were measured at +0.70 V versus SCE, which was due to the electrooxidation of enzymatically produced H2O2. The effects of the thickness of the polymeric film, pH, temperature, substrate and enzyme concentrations on the response of the enzyme electrode were investigated. The optimum pH was found to be pH 7.4 at 25 °C. The steady-state current of these enzyme electrodes were reproducible within ±5.0% of the relative error. Response time was found to be 30–50 s and upper limit of the linear working portions was found to be 1.2 mM choline and acetylcholine concentrations in which produced detectable currents were 1.0×10−6 M substrate concentrations. The apparent Michaelis–Menten constant and the activation energy of this immobilized enzyme system were found to be 1.74 mM acetylcholine and 14.92 kJ mol−1, respectively. The effects of interferents and stability of the enzyme electrodes were also investigated.
The preparations and performances of the novel amperometric biosensors for glucose based on immob... more The preparations and performances of the novel amperometric biosensors for glucose based on immobilized glucose oxidase (GOD) on modified Pt electrodes are described. Two types of modified electrodes for the enzyme immobilization were used in this study, polyvinylferrocene (PVF) coated Pt electrode and gold deposited PVF coated Pt electrode. A simple method for the immobilization of GOD enzyme on the modified electrodes was described. The enzyme electrodes developed in this study were called as PVF-GOD enzyme electrode and PVF-Au-GOD enzyme electrode, respectively. The amperometric responses of the enzyme electrodes were measured at constant potential, which was due to the electrooxidation of enzymatically produced H2O2. The electrocatalytic effects of the polymer, PVF, and the gold particles towards the electrooxidation of the enzymatically generated H2O2 offers sensitive and selective monitoring of glucose. The biosensor based on PVF-Au-GOD electrode has 6.6 times larger maximum current, 3.8 times higher sensitivity and 1.6 times larger linear working portion than those of the biosensor based on PVF-GOD electrode. The effects of the applied potential, the thickness of the polymeric film, the amount of the immobilized enzyme, pH, the amount of the deposited Au, temperature and substrate concentration on the responses of the biosensors were investigated. The optimum pH was found to be pH 7.4 at 25 °C. Finally the effects of interferents, stability of the biosensors and applicability to serum analysis of the biosensor were also investigated.
The electrooxidation behavior of iodide, thiocyanate, and cyanide on poly(vinylferrocenium)-coate... more The electrooxidation behavior of iodide, thiocyanate, and cyanide on poly(vinylferrocenium)-coated Pt electrodes was investigated using cyclic voltammetry and differential pulse anodic stripping voltammetry. IR and UV spectroscopic data, and differential scanning calorimetry (DSC) measurements indicated that these anions were incorporated in the polymeric structure as a result of anion exchange. Anodic stripping of these anions from the film was carried out after the initial preconcentration. Cyanide uptake was found to cause an irreversible change in the physical properties of the film, whereas thiocyanate and iodide are merely incorporated in the film structure as counter ions.
A new enzyme electrode for the determination of alcohols was developed by immobilizing alcohol ox... more A new enzyme electrode for the determination of alcohols was developed by immobilizing alcohol oxidase in polvinylferrocenium matrix coated on a Pt electrode surface. The amperometric response due to the electrooxidation of enzymatically generated H2O2 was measured at a constant potential of +0.70 V versus SCE. The effects of substrate, buffer and enzyme concentrations, pH and temperature on the response of the electrode were investigated. The optimum pH was found to be pH 8.0 at 30 °C. The steady-state current of this enzyme electrode was reproducible within ±5.0% of the relative error. The sensitivity of the enzyme electrode decreased in the following order: methanol>ethanol>n-butanol>benzyl alcohol. The linear response was observed up to 3.7 mM for methanol, 3.0 mM for ethanol, 6.2 mM for n-butanol, and 5.2 mM for benzyl alcohol. The apparent Michaelis–Menten constant (KMapp) value and the activation energy, Ea, of this immobilized enzyme system were found to be 5.78 mM and 38.07 kJ/mol for methanol, respectively.
Co-immobilization of two enzymes, glucose oxidase and invertase, in polyvinyl(ferrocenium) perchl... more Co-immobilization of two enzymes, glucose oxidase and invertase, in polyvinyl(ferrocenium) perchlorate (PVF+ClO−4) film led to the development of a simple, sensitive, stable and low-cost sucrose sensor. Invertase catalyses the conversion of sucrose to α-glucose and β-fructose. Phosphate ions used in the medium catalyse the conversion of α-glucose to β-glucose, eliminating the need for the commonly used third enzyme, mutarotase, for mutarotation. Glucose oxidase catalyses the oxidation of β-glucose to gluconic acid, producing H2O2. Current due to H2O2 oxidation catalysed by PVF+ centres was measured, in contrast to most existing sucrose electrodes, which rely on measurement of the O2 reduction current.
A simple, sensitive, stable and low-cost glucose sensor with a fast response that operates under ... more A simple, sensitive, stable and low-cost glucose sensor with a fast response that operates under aerobic solution conditions is described. The electrode consists of a polyvinylferrocenium-perchlorate-coated Pt surface onto which the enzyme is attached. The current response of the electrode was determined by measuring either cyclic voltammetric peak current values or steady state current values obtained after a constant-potential step. The effects of glucose concentration, the amount of enzyme immobilized, the thickness of the polymeric layer and the operating temperature on the response of the enzyme electrode were studied. The effects of two common physiological sources of interference were also investigated. A mechanism for the operation of the electrode is also proposed.
Conducting polymer composites of polyvinylferrocene and polypyrrole (PVF/PPy) were synthesized ch... more Conducting polymer composites of polyvinylferrocene and polypyrrole (PVF/PPy) were synthesized chemically by the in situ polymerization of pyrrole in the presence of PVF using FeCl3 as oxidant. Acetic (CH3COOH) and boric (H3BO3) acids were used as the synthesis medium. Effects of the synthesis medium on the properties of the PVF/PPy composite were investigated. The PVF/PPy composites and homopolymers were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and magnetic susceptibility techniques. Conductivity measurements were performed using the four‐probe technique. We found that the conductivities of PVF/PPy‐H3BO3 (1.19 S cm−1) and PVF/PPy‐CH3COOH (4.5×10−1 S cm−1) increased relative to those of the homopolymers of PPy‐H3BO3 (2.1×10−2 S cm−1) and PPy‐CH3COOH (1.2×10−2 S cm−1) due to the interaction of PVF with the pyrrole moiety. The stability of all homopolymers and composites were investigated by thermogravimetric analysis and by conductivity measurements during heating‐cooling cycles. There was a small drop in conductivity caused by the annealing of PVF/PPy composites at 70°C. The conductivity of all samples increased with temperature and exhibited stable electrical behavior with increasing temperature. TGA analysis of samples showed that the composites were more stable than the homopolymers or PVF separately. The magnetic susceptibility values of samples were negative, except for PVF/PPy‐H3BO3. Morphology changes of the composites investigated by scanning electron microscopy (SEM), attributed to synthesis conditions, have a significant effect on their conductivity.
... a Department of Chemistry, Selçuk University, Konya 42075, Turkey. b Department of Chemical E... more ... a Department of Chemistry, Selçuk University, Konya 42075, Turkey. b Department of Chemical Engineering, Selçuk University, Konya 42075, Turkey. Received 8 April 2011; revised 24 June 2011; accepted 24 June 2011. Available online 2 July 2011. Abstract. ...
Coimmobilization of beta-galactosidase and glucose oxidase in a redox polymer, polyvinylferroceni... more Coimmobilization of beta-galactosidase and glucose oxidase in a redox polymer, polyvinylferrocenium perchlorate (PVF+ ClO4-), led to the development of an enzyme electrode for the determination of lactose. The amperometric response of the electrode was measured at +0.70 V vs. SCE, which was due to the electrooxidation of enzymatically produced H2O2. The effects of the substrate and buffer concentrations as well as the pH on the electrode response were elucidated.
A simple method of enzyme immobilization was investigated, which is useful for development of enz... more A simple method of enzyme immobilization was investigated, which is useful for development of enzyme electrodes based on polyvinylferrocenium perchlorate coated Pt electrode surface. Enzymes were incorporated into the polymer matrix via ion exchange process by immersing polyvinylferrocenium perchlorate coated Pt electrode in enzyme solution for several times. Choline and acetylcholine enzyme electrodes were developed by co-immobilizing choline oxidase and acetylcholinesterase in polyvinylferrocenium perchlorate matrix coated on a Pt electrode surface. The amperometric responses of the enzyme electrodes were measured at +0.70 V versus SCE, which was due to the electrooxidation of enzymatically produced H2O2. The effects of the thickness of the polymeric film, pH, temperature, substrate and enzyme concentrations on the response of the enzyme electrode were investigated. The optimum pH was found to be pH 7.4 at 25 °C. The steady-state current of these enzyme electrodes were reproducible within ±5.0% of the relative error. Response time was found to be 30–50 s and upper limit of the linear working portions was found to be 1.2 mM choline and acetylcholine concentrations in which produced detectable currents were 1.0×10−6 M substrate concentrations. The apparent Michaelis–Menten constant and the activation energy of this immobilized enzyme system were found to be 1.74 mM acetylcholine and 14.92 kJ mol−1, respectively. The effects of interferents and stability of the enzyme electrodes were also investigated.
The preparations and performances of the novel amperometric biosensors for glucose based on immob... more The preparations and performances of the novel amperometric biosensors for glucose based on immobilized glucose oxidase (GOD) on modified Pt electrodes are described. Two types of modified electrodes for the enzyme immobilization were used in this study, polyvinylferrocene (PVF) coated Pt electrode and gold deposited PVF coated Pt electrode. A simple method for the immobilization of GOD enzyme on the modified electrodes was described. The enzyme electrodes developed in this study were called as PVF-GOD enzyme electrode and PVF-Au-GOD enzyme electrode, respectively. The amperometric responses of the enzyme electrodes were measured at constant potential, which was due to the electrooxidation of enzymatically produced H2O2. The electrocatalytic effects of the polymer, PVF, and the gold particles towards the electrooxidation of the enzymatically generated H2O2 offers sensitive and selective monitoring of glucose. The biosensor based on PVF-Au-GOD electrode has 6.6 times larger maximum current, 3.8 times higher sensitivity and 1.6 times larger linear working portion than those of the biosensor based on PVF-GOD electrode. The effects of the applied potential, the thickness of the polymeric film, the amount of the immobilized enzyme, pH, the amount of the deposited Au, temperature and substrate concentration on the responses of the biosensors were investigated. The optimum pH was found to be pH 7.4 at 25 °C. Finally the effects of interferents, stability of the biosensors and applicability to serum analysis of the biosensor were also investigated.
The electrooxidation behavior of iodide, thiocyanate, and cyanide on poly(vinylferrocenium)-coate... more The electrooxidation behavior of iodide, thiocyanate, and cyanide on poly(vinylferrocenium)-coated Pt electrodes was investigated using cyclic voltammetry and differential pulse anodic stripping voltammetry. IR and UV spectroscopic data, and differential scanning calorimetry (DSC) measurements indicated that these anions were incorporated in the polymeric structure as a result of anion exchange. Anodic stripping of these anions from the film was carried out after the initial preconcentration. Cyanide uptake was found to cause an irreversible change in the physical properties of the film, whereas thiocyanate and iodide are merely incorporated in the film structure as counter ions.
A new enzyme electrode for the determination of alcohols was developed by immobilizing alcohol ox... more A new enzyme electrode for the determination of alcohols was developed by immobilizing alcohol oxidase in polvinylferrocenium matrix coated on a Pt electrode surface. The amperometric response due to the electrooxidation of enzymatically generated H2O2 was measured at a constant potential of +0.70 V versus SCE. The effects of substrate, buffer and enzyme concentrations, pH and temperature on the response of the electrode were investigated. The optimum pH was found to be pH 8.0 at 30 °C. The steady-state current of this enzyme electrode was reproducible within ±5.0% of the relative error. The sensitivity of the enzyme electrode decreased in the following order: methanol>ethanol>n-butanol>benzyl alcohol. The linear response was observed up to 3.7 mM for methanol, 3.0 mM for ethanol, 6.2 mM for n-butanol, and 5.2 mM for benzyl alcohol. The apparent Michaelis–Menten constant (KMapp) value and the activation energy, Ea, of this immobilized enzyme system were found to be 5.78 mM and 38.07 kJ/mol for methanol, respectively.
Co-immobilization of two enzymes, glucose oxidase and invertase, in polyvinyl(ferrocenium) perchl... more Co-immobilization of two enzymes, glucose oxidase and invertase, in polyvinyl(ferrocenium) perchlorate (PVF+ClO−4) film led to the development of a simple, sensitive, stable and low-cost sucrose sensor. Invertase catalyses the conversion of sucrose to α-glucose and β-fructose. Phosphate ions used in the medium catalyse the conversion of α-glucose to β-glucose, eliminating the need for the commonly used third enzyme, mutarotase, for mutarotation. Glucose oxidase catalyses the oxidation of β-glucose to gluconic acid, producing H2O2. Current due to H2O2 oxidation catalysed by PVF+ centres was measured, in contrast to most existing sucrose electrodes, which rely on measurement of the O2 reduction current.
A simple, sensitive, stable and low-cost glucose sensor with a fast response that operates under ... more A simple, sensitive, stable and low-cost glucose sensor with a fast response that operates under aerobic solution conditions is described. The electrode consists of a polyvinylferrocenium-perchlorate-coated Pt surface onto which the enzyme is attached. The current response of the electrode was determined by measuring either cyclic voltammetric peak current values or steady state current values obtained after a constant-potential step. The effects of glucose concentration, the amount of enzyme immobilized, the thickness of the polymeric layer and the operating temperature on the response of the enzyme electrode were studied. The effects of two common physiological sources of interference were also investigated. A mechanism for the operation of the electrode is also proposed.
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