Fabrication of a promising immobilization platform based on electrochemical synthesis of a conjugated polymer (original) (raw)
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Analytical Chemistry, 1990
o-Phenylenedlamlne has been used for glucose oxidase (GOx) lmmobillzatlon on Pt electrodes by electrochemical polymerlzatlon at +0.65 V vs SCE. By thls approach the enzyme Is entrapped In a strongly adherent, highly reproduclble thln membrane, whose thickness Is around 10 nm. This one-step procedure produces a glucose sensor wlth a response time less than 1 s, an active enzyme loading higher than 3 units/cm2 of electrode surface, a high sensitlvity, and a sufflclently wlde llnear range. The glucose response shows an apparent Mkhaells-Menten constant, K', = 14.2 mM, and a limltlng current density, of 181 pA/cm2. The product &D of partltion and dlffusion coefficients of glucose in the polymer film is on the order of lo-'' cm2/s. Due to permselectlvlty characteristics of the membrane, the access of ascorbate, a common Interfering specles, to the electrode surface Is blocked. To our knowledge, thls represents the first report of a membrane capable, at the same time, of immobilizing GOx and rejecting ascorbate. The Interesting electrode behavlor can be rationallzed by using an existing model predlctlng the amperometrlc response of an Immobliized GOx system.
A low cost, easy to fabricate, simple to operate, portable and disposable biosensor based upon the enzyme glucose oxidase (GOD) has been developed. A polymer matrix of Polyethylenemine (PEI) and Poly Carbamoylsulphonate (PCS) hydrogel has been used for the immobilization of GOD on a Platinum (Pt) tip of a screen printed graphite electrode. A multi channel potentiostat has been utilized in the electrode configuration for the amperometric measurement of glucose. The developed Pt/PCS+PEI/GOD glucose biosensor system could offer a reliable method of glucose determination in standard stock solutions. The designed glucose bio-sensor system has been duly characterized and the results obtained are presented. The biosensor has been found to show a sensitivity of 0.72 ± 0.15 nA/µM. Also, the specificity of the enzyme electrode and the storage stability of the GOD based biosensor system have been studied. The sensor system has also been tested with the real samples of fruit juice, soft drink and human blood. The biosensor system has been found to possess a potential for food analysis and clinical utility.
Organic Electronics, 2019
First example of electrochemically polymerized thiazolothiazole containing electrochromic conducting polymer; Poly(2,5-di(furan-2-yl)thiazolo[5,4-d]thiazole) (PTTzFr) was obtained via cyclic voltammetry. The polymer structure bears furan unit as the donor and thiazolothiazole unit as the acceptor. PTTzFr film was obtained on an ITO coated glass slide and its electrochemical and optoelectronic properties were investigated. Polymeric film showed reversible redox behavior along with reversible electrochromic behavior from reddish orange to grey having a band gap value of 1.80 eV. It has fast switching times (0.3 s and 0.4 s) with high optical contrast values at visible and NIR regions (38% at 460 nm and 63% at 1225 nm). Optoelectronic device application was performed by constructing a dual type electrochromic device (ECD) with poly(3,4-ethylenedioxythiophene) (PEDOT). Resulting device showed a remarkable optical memory without changing its % transmittance value during 200 s at 450 nm. Additionally, to construct a sensing interface, in the present work, a conjugated polymer (PTTzFr) containing biosensor was constructed for the glucose analysis. The architecture showed a promising sensing system for biosensor application. For the preparation of the proposed sensor, polymer film was coated on graphite electrode surface and fabricated as a glucose biosensor with immobilization of glucose oxidase. The biosensor was successfully applied for the determination of glucose in beverage. Under optimized conditions, the proposed sensor served a low detection limit (12.8 × 10 −3 mM), and high sensitivity (65.44 μAmM −1 cm −2). To the best of our knowledge, a sensor design and ECD construction using electrochemically polymerized PTTzFr that shows superior properties for both systems were attempted for the first time, and this approach resulted in improved biosensor and ECD characteristics.
Journal of The Electrochemical Society, 2018
A new approach was developed using a combination of a conducting polymer; poly(3,4-ethylenedioxythiophene) (PEDOT) with the electrochemically produced polymer of N-ferrocenyl-3-(1H-pyrrol-1-yl)aniline, (PFcPyBz) layer for the enzyme scaffolding resulting in excellent analytical parameters. To organize such a surface, graphite electrode was coated with a PEDOT layer and it was used as a transducer for electrochemical deposition of the polymer of a newly synthesized FcPyBz monomer. Using a PEDOT layer as the working electrode improved localization of the PFcPyBz on the transducer surface while enhancing the biosensor performance. A simple binding of glucose oxidase (GOx) as a test enzyme on this new polymeric platform was achieved using glutaraldehyde (GA) as the cross linker. The low limit of detection and high sensing sensitivity on glucose for the biosensor are estimated as 54 μM and 112.2 μA/mMcm 2 , respectively. The surface characterizations of the modified electrodes were investigated by cyclic voltammetry (CV), attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) techniques. Finally, different kinds of beverages were tested for sensor reliability with high accuracy. A well-known disorder, diabetes mellitus occurs via an increase in glucose concentration in human blood. Since it is spreading worldwide , its careful and precise detection gained importance to reduce the threat. 1,2 Mirroring the importance of the disease is the worldwide interest leading to publishing a number of articles per year. These developments have opened ways to the wide array of emerging applications in glucose biosensors. Development of the glucose oxidase based enzyme biosensors by different immobilization techniques on various kind of electrodes had been studied for several decades. 3,4 Conjugated polymers (CPs) promise to advance a number of real-world technologies. Of these applications, they are particularly attractive for uses in enzyme biosensors for environmental and health monitoring. Their unique properties such as high electrical conductivity, ease of preparation and good environmental and chemical stability have motivated the use of CPs in the form of thin films for biosensors. 5,6 CP based biosensors bring simple, accurate, reliable and low-cost determination of various analytes and act as a very effective analytical tool in the multiple areas. This description is also supported by a number of researchers using the CPs as an immobilization architecture. 7-10 PEDOT has been reported to exhibit superior stability in conductivity compared to other available polymers and this property prompted us to use the PEDOT film as a transducer in order to obtain a more stable scaffolding for the glucose sensor. Brett and co-workers developed a PEDOT/poly (methylene blue) (PMB) modified glassy carbon electrode (GCE) for a GOx-based biosensor. 11 PEDOT films generated on top of PMB modified bare electrode was used to enhance the stability of PMB modified electrode. The proposed sensing architecture (GOx/PEDOT/PMB/GCE) showed better biosensor performance than the ones for GOx/GCE and GOx/PEDOT/GCE biosensors. In another work, Si reported a simple synthesis of a hybrid film by elec-tropolymerizing 3,4-ethylenedioxythiophene (EDOT) on nanoporous gold (NPG) for applications in amperometric glucose biosensors. 12 They finally concluded that the NPG/PEDOT/GOx biosensor prepared by optimum film thickness is appropriate for effective substrate diffusing. PEDOT is also used as the working electrode for glucose sensing by Ho and co-workers. 13 In this work, PEDOT and ferrocene (Fc) containing polymer were used for not only reducing the working potential but also for improving the stability of the sensor. Moreover, after the invention of the Fc molecule in 1951, scientist paid attention to this sandwich like molecule in many other research areas. 14,15 A huge number of molecules containing Fc moiety were designed and assessed for their possible use in glucose sensing applications. 16,17 Elec-trodeposited copolymer of pyrrole and ferrocene carboxylate modified pyrrole p(Py-FcPy), 18 co-deposition of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) aniline (SNS-NH 2) and 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) amidoferrocenyldithiophosphonate (SNS-NH2-Fc) 19 and copolymer of O-4-(1H-pyrrol-1-yl)-ferrocenyldithiophosphonate (TPFc) with 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)butane-1-amine (TPA) 20 are the examples of the conjugated polymer based electron-mediating support materials for developing GOx immobilized electrodes. Under the light of this, this work will show a significant way to create CPs-based glucose biosensors exhibiting selective responses to a target analyte. Such approach predominantly includes functional-ization of PEDOT bearing surface with newly synthesized Fc moiety containing polymer. In this report, for the first time a PEDOT transducer was designed and a new one-pot synthesized ferrocene containing monomer was electrochemically deposited on a well-known polymer (PEDOT) surface for glucose sensing. Without the PEDOT layer it was difficult to coat PFcPyBz layer on the bare graphite surface. For this reason, the electrode surface is first modified with PEDOT and then coated with PFcPyBz. We described the importance and effect of CPs in biosensor construction that was highlighted in our previous works. 21,22 However, need for a promising analytical devices for glucose sensing with high accuracy and sensitivity has motivated us to design a new sensing system. Designing of the new surface in this study, a highly sensitive and reliable glucose sensor was developed with the help of glucose oxidase (GOx), as a model enzyme. Detailed optimization studies, surface characterization of the polymer layers and the amperomet-ric characterization were performed. Additionally, the testing of the biosensor was conducted using different kinds of commercial beverages. Experimental Chemicals and instrumentation.-All chemicals which were used for monomer synthesis and electrochemical polymerization, were purchased from Aldrich and used without further purification. Materials used for biosensor construction were also obtained from Aldrich. Glucose oxidase enzyme used in this study was (GOx, β-D-glucose: oxygen 1-oxidoreductase, EC 1.1.3.4, 17300 units/g solid) from A. Niger. Electrochemical polymerizations of the EDOT and the FcPyBz) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 144.122.34.94 Downloaded on 2018-12-27 to IP
Sensors and Actuators B-chemical, 2010
We describe here the electropolymerization of catecholamines preoxidized by laccase (Lac) catalysis as a novel protocol to efficiently immobilize glucose oxidase (GOx) at Au electrodes for sensitive amperometric biosensing of glucose. The rates of Lac-catalyzed polymerization in aqueous solutions were found to follow the order of dopamine (DA) > l-noradrenaline (NA) ≫ epinephrine (EP), as examined by visual inspection, UV–vis spectrophotometry, and electrochemical techniques. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the electropolymerization of catecholamines preoxidized by Lac catalysis in the absence and presence of GOx. The GOx immobilized in the poly(l-noradrenaline) (PNA) matrix retained a high enzymatic specific activity, as quantified by UV–vis spectrophotometry and EQCM methods. The PNA-involved enzyme electrode displayed a glucose-assay sensitivity of 38 μA cm−2 mmol−1 L and a limit of detection of 0.4 μmol L−1 at 0.7 V vs. SCE under optimal conditions, being more sensitive than that prepared via preoxidation-free conventional electropolymerization. Sensitivity enhancement was also obtained when DA or EP was used for similar polymerization and GOx-immobilization, and the DA and NA polymer substrates gave almost identical glucose-biosensing performance that were much better than the EP one, suggesting that the NA polymer substrate is a good alternative to the well-recognized DA one. The proposed strategy of high efficiency and universality may have application potentials in many fields, such as biosensing, biocatalysis, and biofuel cells.
Journal of the Brazilian Chemical Society, 2001
Neste trabalho é apresentada a co-imobilização de GOx e ferroceno numa matriz polimérica através de um método simples de uma etapa. Esse procedimento para a imobilização de ferroceno como mediador da reação enzimática não envolve a modificação do monômero ou da enzima, o que poderia levar à perda de sua atividade. A incorporação de ferroceno se traduz no incremento da sensibilidade, comparado ao sensor sem mediador redox (1,5 vs 0,23 µA mmol-1 L cm-2) e diminuição do potencial de trabalho até 0,4 V. O sensor desenvolvido mostra resposta linear até 10 mmol L-1 e um tempo de resposta de 2 s, além de razoável estabilidade depois de uma semana de uso. The co-immobilization of GOx and ferrocene in a polymeric matrix by a one-step simple method is presented. This procedure to immobilize ferrocene as mediator implies the absence of modification of the monomer or the enzyme that would lead to the loss of its activity. Ferrocene incorporation results in an increase of sensitivity compared with the sensor prepared without the redox mediator (1.5 vs 0.23 µA mmol-1 L cm-2) and the decrease of the working potential to 0.4 V. The prepared sensor shows linear response till 10 mmol L-1 and response time of 2 s, in addition to reasonable stability after one week.
Journal of Electroanalytical Chemistry, 2005
Platinization has been used to increase electrode surface area and therefore electrode sensitivity. However there are few studies on platinization conditions and their effects on the reaction diffusion of enzyme biosensors. We report the fabrication of sensitive (192 ± 48 lA cm À2 mM À1 ) amperometric glucose sensors. The repeatability (precision) was at worst 2.32% ± 1.22% of the measured value, the limit of detection was 0.94 mM and the detection was linear up to at least 25 mM. Sensor-to-sensor variability was 24%. The half-life of the sensors at 21°C was 12 days. Shelf life at 4°C was at least one month without a decrease in sensitivity. Under continuous operation, sensors performed at least 120 determinations without a large decrease in sensitivity; however; fluctuations in current response indicate that frequent calibration is required. Sensors were used for the determination of glucose in apple juice and white wine. High sensitivity was achieved by improving the conditions of platinization and entrapment of glucose oxidase in poly-o-phenylenediamine. Potentiostatic platinization at À100 or À50 mV vs. AgjAgCl resulted in mechanically stable deposits unlike those formed at the commonly used À250 mV. Large concentrations of glucose oxidase did not inhibit the electropolymerization of ophenylenediamine. H 2 O 2 diffusion experiments using polished and platinized, bare and polymer-covered rotating disk electrodes suggest that H 2 O 2 diffuses from the bulk of the solution through the polymer film to be oxidized at the platinized surface and the diffusion is apparently one-dimensional with platinization compensating for the coverage of catalytic sites by the polymer. Conversely, when, on a platinized electrode, glucose oxidase is immobilized in a thin poly-o-phenylenediamine film, substrate diffuses rapidly through the porous matrix and H 2 O 2 is produced throughout the enzyme/polymer film. Under these conditions, diffusion is apparently multidirectional and platinization results in an effectively large increase in surface area that results in a high amperometric response. A mathematical model of the reaction-diffusion matrix of polished electrodes supports this interpretation of the increased response.
Sensors, 2011
In this study, a novel amperometric glucose biosensor with immobilization of glucose oxidase on electrochemically polymerized polyaniline-polyvinylsulphonate (Pani-Pvs) films has been accomplished via the entrapment technique. Electropolymerization of aniline on the Pt surface of the Pt electrode was carried out at constant potential (0.75 V, vs. Ag/AgCl) using an electrochemical cell containing aniline and polyvinylsulphonate. Firstly, the optimum working conditions for preparing polyaniline-polyvinylsulfonate films were investigated. Determination of glucose was carried out by the oxidation of enzymatically produced H 2 O 2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and the optimum pH value was found to be 7.5. The storage stability and operational stability of the enzyme electrode were also studied. The results show that 75% of the response current was retained after 16 activity assays. The prepared glucose biosensor retained 80.6% of initial activity after 40 days when stored in 0.1 M phosphate buffer solution at 4 °C.
Biosensors based on oxidases immobilized in various conducting polymers
Sensors and Actuators B: Chemical, 1995
The electrodeposited organic polymers polypyrrole, poly(N-methylpyrrole), poly(u-phenylenediamine) and polyaniline are compared as matrices for the immobilization of glucose oxidase in the preparation of amperometric glucose biosensors. Enzyme entrapment in the polymer layer is obtained by electrodeposition of polymers from solutions of monomers containing dissolved enzyme. For all examined sensors a useful and almost linear range of response to glucose is observed up to at least 20 mM of glucose. The best sensitivity of response is obtained for a glucose sensor made of poly(o-phenylenediamine) and polypyrrole. A linear response up to 20 mM glucose is also obtained in flow-injection measurements for a glucose/polypyrrole sensor. Poly(o-phenylenediamine) is also used for satisfactory immobilization of choline oxidase in the preparation of a choline sensor, whereas a lactate biosensor has been prepared by immobilization of lactate oxidase in polypyrrole.
Covalently immobilized enzymes on biocompatible polymers for amperometric sensor applications
Biosensors and Bioelectronics, 1996
Glucose oxidase or choline oxidase were covalently immobilized on the surface of 2-hydroxyethyi and glycidyl methacrylate copolymer membranes. The polymerization was induced by gamma irradiation at low temperature. The enzyme modified polymers were applied on Clark-type or platinum electrodes to form amperometric sensors based on the electrochemical measurements of oxygen or hydrogen peroxide. Glucose and choline content in standard solutions were measured and linear calibration curves were determined. The sensors studied showed a response time of less than 2 min and the observed linear ranges were increased with respect to usual biosensors owing to the diffusion-limiting effects of the membranes used. The influence of the copolymer composition on the electrochemical response and on the retained enzyme activity were explored for verifying the optimum analytical performance. The immobilized enzyme membranes stored in suitable buffers were very stable and showed a decrease up to 20% in the electrode response after 3 months of constant use.