| 1. |
- de Mattos, I L, et al.
(author)
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Development of biosensors based on hexacyanoferrates.
- 2000
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In: Talanta. - 1873-3573. ; 52:5, s. 791-799
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Journal article (peer-reviewed)abstract
- Ferric and copper hexacyanoferrates (PB and CuHCF, respectively) were electrodeposited on glassy carbon electrodes providing a suitable catalytic surface for the amperometric detection of hydrogen peroxide. Additionally glucose oxidase was immobilized on top of these electrodes to form glucose biosensors. The biosensors were made by casting glucose oxidase-Nafion layers onto the surface of the modified electrodes. The operational stability of the films and the biosensors were evaluated by injecting a standard solution (5 muM H(2)O(2) for PB, 5 mM H(2)O(2) for CuHCF and 2.5 mM glucose for both) over 5-10 h in a flow-injection system with the electrodes polarized at -50 (PB) and -200 mV (CuHCF) versus Ag/AgCl, respectively. The glucose biosensors demonstrated suitability for glucose determination: 0.0-2.5 mM (R(2)=0.9977) for PB and 0.0-10 mM (R(2)=0.9927) for CuHCF, respectively. The visualization of the redox catalyst modifiers (PB and CuHCF films) was presented by scanning electron micrographs.
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| 2. |
- de Mattos, I L, et al.
(author)
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Evaluation of glucose biosensors based on Prussian Blue and lyophilised, crystalline and cross-linked glucose oxidases (CLEC(R)).
- 2001
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In: Talanta. - 1873-3573. ; 54:5, s. 963-974
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Journal article (peer-reviewed)abstract
- Glucose biosensors based on lyophilised, crystalline and cross-linked glucose oxidase (GOx, CLEC(R)) and commercially available lyophilised GOx immobilised on top of glassy carbon electrodes modified with electrodeposited Prussian Blue are critically compared. Two procedures were carried out for preparing the biosensors: (1) deposition of one layer of adsorbed GOx dissolved in an aqueous solution followed by deposition of two layers of low molecular weight Nafion(R) dissolved in 90% ethanol, and (2) deposition of two layers of a mixture of GOx with Nafion dissolved in 90% ethanol. The performance of the biosensors was evaluated in terms of linear response range for hydrogen peroxide and glucose, detection limit, and susceptibility to some common interfering species (ascorbic acid, acetaminophen and uric acid). The operational stability of the biosensors was evaluated by applying a steady potential of -50 mV versus Ag/AgCl to the glucose biosensor and injecting standard solutions of hydrogen peroxide and glucose (50 muM and 1.0 mM, respectively, in phosphate buffer) for at least 5 h in a flow-injection system. Scanning electron microscopy was used for visualisation of the Prussian Blue redox catalyst and in the presence of the different GOx preparations on the electrode surface.
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| 3. |
- Trashin, Stanislav A., et al.
(author)
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Improvement of direct bioelectrocatalysis by cellobiose dehydrogenase on screen printed graphite electrodes using polyaniline modification
- 2009
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In: Bioelectrochemistry. - : Elsevier BV. - 1878-562X .- 1567-5394. ; 76:1-2, s. 87-92
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Journal article (peer-reviewed)abstract
- Modification of graphite based screen printed electrodes (SPEs) by electrosynthesised polyaniline (PANI) has been applied to improve the electron exchange between cellobiose dehydrogenase (CDH, EC 1.1.99.18) from the ascomycete Myriococcum thermophilum and the surface of the SPE. The redox intermediate layer of the conducting polymer promotes the bioelectrocatalysis providing a higher current for lactose oxidation at a lower potential compared to CDH immobilised on a plain SPE. The current of the SPE vertical bar PANI vertical bar CDH electrode was more than 5 times higher as compared to that of a SPE vertical bar CDH electrode at a potential of 0 mV vs. Ag vertical bar AgCl. When comparing the response obtained through direct electron transfer with that obtained through mediated electron transfer. it was clearly observed that the improved current of the SPE vertical bar PANI vertical bar CDH electrode is due to the specific role of PANI, rather than caused by a rise of enzyme loading. The operational stability of the enzyme electrode based on PANI modified SPE was 5 times higher compared with that based on plain SPE. (C) 2009 Elsevier B.V. All rights reserved
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| 4. |
- Varfolomeyev, S, et al.
(author)
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Postgenomic chemistry (IUPAC Technical Report)
- 2005
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In: Pure and Applied Chemistry. - : Walter de Gruyter GmbH. - 0033-4545 .- 1365-3075. ; 77:9, s. 1641-1654
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Journal article (peer-reviewed)abstract
- Numerous areas of chemistry can benefit from the ongoing genomic revolution. Here, we discuss and highlight trends in chemistry in the postgenomic era. The areas of interest include combinatorial approaches in organic chemistry; design and analysis of proteins containing unnatural amino acids; trace element-containing proteins; design and characterization of new enzyme types; applications of postgenomic chemistry in drug design; identification of lipid networks and global characterization of lipid molecular species; development of recombinant and self-proliferating polymers; and applications in food chemistry and bioanalytical chemistry based on new nanoanalytical systems and novel recognition elements.
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| 5. |
- Ricci, F, et al.
(author)
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Investigation of the effect of different glassy carbon materials on the performance of Prussian blue based sensors for hydrogen peroxide
- 2003
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In: Electroanalysis. - : Wiley. - 1040-0397 .- 1521-4109. ; 15:3, s. 175-182
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Journal article (peer-reviewed)abstract
- Three different kinds of glassy carbon (GC-R, GC-K, GC-G) were equally pretreated, further modified with electrochemically deposited Prussian Blue and used as sensors for hydrogen peroxide at an applied potential of -50 mV (vs. Ag|AgCl). Their performance was evaluated with respect to the following parameters: the coverage and electrochemistry of the electrodeposited Prussian Blue, the sensitivity and the lower limit of detection for hydrogen peroxide, and the operational stability of the sensors. GC-R showed the best behavior concerning the surface coverage and the operational stability of the electrodeposited Prussian Blue. For this electrode the sensitivity for hydrogen peroxide (10 M) was 0.25 A/M cm2 and the detection limit was 0.1 M. Scanning electron microscopy was used to study the surfaces of the three electrodes before and after the electrodeposition of Prussian Blue and to search for the reason for the three different behaviors between the different glassy carbon materials. The Prussian Blue modified GC-R was also used for the construction of a glucose biosensor based on immobilizing glucose oxidase in Nafion membranes on top of electrodeposited Prussian Blue layer. The operational stability of the glucose biosensors was studied in the flow injection mode at an applied potential of -50 mV (vs. Ag|AgCl) and alternatively injecting standard solutions of hydrogen peroxide (10 M) and glucose (1 mM) for 3 h. For the GC-R based biosensor a 2.8% decrease of the initial glucose response was observed.
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| 6. |
- Sekretaryova, Alina, et al.
(author)
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Cholesterol Self-Powered Biosensor
- 2014
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In: Analytical Chemistry. - : American Chemical Society. - 0003-2700 .- 1520-6882. ; 86:19, s. 9540-9547
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Journal article (peer-reviewed)abstract
- Monitoring the cholesterol level is of great importance, especially for people with high risk of developing heart disease. Here we report on reagentless cholesterol detection in human plasma with a novel single-enzyme, membrane-free, self-powered biosensor, in which both cathodic and anodic bioelectrocatalytic reactions are powered by the same substrate. Cholesterol oxidase was immobilized in a sol-gel matrix on both the cathode and the anode. Hydrogen peroxide, a product of the enzymatic conversion of cholesterol, was electrocatalytically reduced, by the use of Prussian blue, at the cathode. In parallel, cholesterol oxidation catalyzed by mediated cholesterol oxidase occurred at the anode. The analytical performance was assessed for both electrode systems separately. The combination of the two electrodes, formed on high surface-area carbon cloth electrodes, resulted in a self-powered biosensor with enhanced sensitivity (26.0 mA M-1 cm(-2)), compared to either of the two individual electrodes, and a dynamic range up to 4.1 mM cholesterol. Reagentless cholesterol detection with both electrochemical systems and with the self-powered biosensor was performed and the results were compared with the standard method of colorimetric cholesterol quantification.
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| 7. |
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| 8. |
- Sekretaryova, Alina N., et al.
(author)
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Reagentless Biosensor Based on Glucose Oxidase Wired by the Mediator Freely Diffusing in Enzyme Containing Membrane
- 2012
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 84:3, s. 1220-1223
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Journal article (peer-reviewed)abstract
- Wiring glucose oxidase in the membrane with an immobilized mediator is possible due to the diffusion ability of the latter, if the enzyme containing membrane is formed according to the proposed protocol, including exposing proteins to water–organic mixtures with the high content of organic solvent. In the course of the study, the new glucose oxidase mediator, unsubstituted phenothiazine, was discovered. The diffusion coefficient of the mediator in the resulting membrane is independent of the presence of enzyme. The cyclic voltammograms of the enzyme electrode after appearance of the only glucose in solution obtain a well-defined catalytic shape, which is normally observed for both the enzyme and the mediator in solution. Analytical performances of the resulting biosensor are comparable to the advanced second generation ones, which, however, require covalent linking of the mediator either to the membrane forming polymer or to the enzyme. Even without such covalent linking, the reported biosensor is characterized by an appropriate long-term operational stability allowing reagentless sensing.
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| 9. |
- Sekretaryova, Alina, et al.
(author)
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Unsubstituted phenothiazine as a superior water-insoluble mediator for oxidases
- 2014
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In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 53, s. 275-282
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Journal article (peer-reviewed)abstract
- The mediation of oxidases glucose oxidase (GOx), lactate oxidase (LOx) and cholesterol oxidase (ChOx) by a new electron shuttling mediator, unsubstituted phenothiazine (PTZ), was studied. Cyclic voltammetry and rotating-disk electrode measurements in nonaqueous media were used to determine the diffusion characteristics of the mediator and the kinetics of its reaction with GOx, giving a second-order rate constant of 7.6×103–2.1×104 M−1 s−1 for water–acetonitrile solutions containing 5–15% water. These values are in the range reported for commonly used azine-type mediators, indicating that PTZ is able to function as an efficient mediator. PTZ and GOx, LOx and ChOx were successfully co-immobilised in sol–gel membrane on a screen-printed electrode to construct glucose, lactate and cholesterol biosensors, respectively, which were then optimised in terms of stability and sensitivity. The electrocatalytic oxidation responses showed a dependence on substrate concentration ranging from 0.6 to 32 mM for glucose, from 19 to 565 mM for lactate and from 0.015 to 1.0 mM for cholesterol detection. Oxidation of substrates on the surface of electrodes modified with PTZ and enzyme membrane was investigated with double-step chronoamperometry and the results showed that the PTZ displays excellent electrochemical catalytic activities even when immobilised on the surface of the electrode.
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