| 1. |
- Ackermann, Yvonne, et al.
(författare)
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Design of a bioelectrocatalytic electrode interface for oxygen reduction in biofuel cells based on a specifically adapted Os-complex containing redox polymer with entrapped Trametes hirsuta laccase
- 2010
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Ingår i: Electrochemistry communications. - : Elsevier. - 1388-2481 .- 1873-1902. ; 12:5, s. 640-643
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Tidskriftsartikel (refereegranskat)abstract
- The design of the coordination shell of an Os-complex and its integration within an electrodeposition polymer enables fast electron transfer between an electrode and a polymer entrapped high-potential laccase from the basidiomycete Trametes hirsuta. The redox potential of the Os3+/2+-centre tethered to the polymer backbone (+720 mV vs. NHE) is perfectly matching the potential of the enzyme (+780 mV vs. NHE at pH 6.5). The laccase and the Os-complex modified anodic electrodeposition polymer were simultaneously precipitated on the surface of a glassy carbon electrode by means of a pH-shift to 2.5. The modified electrode was investigated with respect to biocatalytic oxygen reduction to water. The proposed modified electrode has potential applications as biofuel cell cathode.
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| 2. |
- Aleksejeva, Olga, et al.
(författare)
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Autotolerant ceruloplasmin based biocathodes for implanted biological power sources
- 2021
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Ingår i: Bioelectrochemistry. - : Elsevier. - 1567-5394 .- 1878-562X. ; 140
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Tidskriftsartikel (refereegranskat)abstract
- High-performance autotolerant bioelectrodes should be ideally suited to design implantable bioelectronic devices. Because of its high redox potential and ability to reduce oxygen directly to water, human ceruloplasmin, HCp, the only blue multicopper oxidase present in human plasma, appears to be the ultimate biocatalyst for oxygen biosensors and also biocathodes in biological power sources. In comparison to fungal and plant blue multicopper oxidases, e.g. Myrothecium verrucaria bilirubin oxidase and Rhus vernicifera laccase, respectively, the inflammatory response to HCp in human blood is significantly reduced. Partial purification of HCp allowed to preserve the native conformation of the enzyme and its biocatalytic activity. Therefore, electrochemical studies were carried out with the partially purified enzyme immobilised on nanostructured graphite electrodes at physiological pH and temperature. Amperometric investigations revealed low reductive current densities, i.e. about 1.65 µA cm−2 in oxygenated electrolyte and in the absence of any mediator, demonstrating nevertheless direct electron transfer based O2 bioelectroreduction by HCp for the first time. The reductive current density obtained in the mediated system was about 12 µA cm−2. Even though the inflammatory response of HCp is diminished in human blood, inadequate bioelectrocatalytic performance hinders its use as a cathodic bioelement in a biofuel cell.
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| 3. |
- Aleksejeva, Olga, et al.
(författare)
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Dual-feature photobioanodes based on nanoimprint lithography for photoelectric biosupercapacitors
- 2022
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Ingår i: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 517
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Tidskriftsartikel (refereegranskat)abstract
- Direct transformation of solar energy into electrical energy by means of biological photosynthesis is considered as an attractive option for sustainable electrical energy production. Thylakoid membranes, the site of photosynthesis, are regarded as a promising biological material for the development of photoelectric biodevices, which produce electrical power consuming only light energy as oxygen evolves at photobioanode upon irradiation and biocathode converts it back to water. Therefore, in this work dual-feature photobioanode based on nanoimprinted gold substrates modified with thylakoids in combination with a capacitive part made of a planar gold substrate coated with a conductive polymer was designed and evaluated, providing open-circuit potential of -0.21 V vs. Ag vertical bar AgCl vertical bar KClsat and a capacitance of ca. 60 F m(-2) both at ambient light and artificial illumination of 400 W m(-2). Combination of thylakoid based dual-feature photobioanode with bilirubin oxidase modified transparent and capacitive indium tin oxide biocathode resulted in a photoelectric biosupercapacitor with remarkable characteristics at ambient light, viz. an open-circuit voltage as high as 0.74 V, which was stable upon charge-discharge cycles during ca. 2 h.
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| 4. |
- Aleksejeva, Olga, et al.
(författare)
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Electrochemistry of a high redox potential laccase obtained by computer-guided mutagenesis combined with directed evolution
- 2019
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Ingår i: Electrochemistry communications. - : Elsevier. - 1388-2481 .- 1873-1902. ; 106
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical characterization of the GreeDo variant of a high redox potential fungal laccase obtained by laboratory evolution together with computer-guided mutagenesis, in comparison to its parental variety (the OB-1 mutant), is presented. Both laccases, when immobilized on graphite electrodes either by direct physical adsorption or covalently attached via gold nanoparticles, were capable of both non-mediated and mediator-based bioelectroreduction of molecular oxygen at low overpotentials. GreeDo exhibited higher open circuit potential values and onset potentials for oxygen bioelectroreduction compared to OB-1. However, even though in homogeneous catalysis GreeDo outperforms OB-1 in terms of turnover numbers and catalytic efficiency, when exposed to high redox potential substrates, direct electron transfer based bioelectrocatalytic currents of GreeDo and OB-1 modified electrodes were similar. High operational stability of freely diffusing GreeDo and also the immobilized enzyme in the acidic electrolyte was registered, in agreement with high storage stability of GreeDo in acidic solutions.
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| 5. |
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| 6. |
- Aleksejeva, Olga, et al.
(författare)
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Photobioanodes Based on Nanoimprinted Electrodes and Immobilized Chloroplasts
- 2022
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Ingår i: ChemElectroChem. - : John Wiley & Sons. - 2196-0216. ; 9:2, s. 37-42
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Tidskriftsartikel (refereegranskat)abstract
- As the global energy demand continues to increase, the interest in photosynthetic energy conversion is growing accordingly. Chloroplasts, photosynthetic organelles present in plants and algae, are attractive candidates for construction of bio solar cells; however, they have been less studied because of their complex membrane system, which restricts electrochemical communication with an electrode surface. Nevertheless, in this work photobioanodes based on planar and nanoimprinted gold substrates modified with chloroplasts were designed and evaluated. Apparently, nanoimprint lithography contributed to higher photocurrent densities, not only owing to the enlarged real surface area, but also due to boosting electrochemical communication between the photosynthetic organelles and the electrode. Combining chloroplast-modified nanoimprinted gold electrodes with a capacitive part made of a planar gold substrate, coated with a conductive polymer, resulted in a dual-feature photobioanode providing a lower open-circuit potential, i. e., -0.11 V vs. Ag|AgCl|KClsat, and an enhanced capacitance of ca. 37 F m(-2) upon illumination of 400 W m(-2).
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| 7. |
- Alsaoub, Sabine, et al.
(författare)
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An Intrinsic Self-Charging Biosupercapacitor Comprised of a High-Potential Bioanode and a Low-Potential Biocathode
- 2017
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Ingår i: ChemPlusChem. - : John Wiley & Sons. - 2192-6506. ; 82:4, s. 576-583
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Tidskriftsartikel (refereegranskat)abstract
- An intrinsic self-charging biosupercapacitor built on a unique concept for the fabrication of biodevices based on redox polymers is presented. The biosupercapacitor consists of a high-potential redox polymer based bioanode and a low-potential redox polymer based biocathode in which the potentials of the electrodes in the discharged state show an apparent potential mismatch E-anode > E-cathode and prevent the use of the device as a conventional biofuel cell. Upon charging, the potentials of the electrodes are shifted to more positive (cathode) and more negative (anode) values because of a change in the a(ox-)to-a(red) ratio within the redox polymer matrix. Hence, a potential inversion occurs in the charged state (E-anode < E-cathode) and an open circuit voltage of >0.4 V is achieved and the bio-device acts as a true biosupercapacitor. The bioanode consists of a novel specifically designed high-potential Os complex modified polymer for the efficient immobilization and electrical wiring of glucose converting enzymes, such as glucose oxidase and flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase. The cathodic side is constructed from a low-potential Os complex modified polymer integrating the O-2 reducing enzyme, bilirubin oxidase. The large potential differences between the redox polymers and the prosthetic groups of the biocatalysts ensure fast and efficient charging of the biodevice.
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| 8. |
- Andoralov, Viktor, et al.
(författare)
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Biofuel cell based on microscale nanostructured electrodes with inductive coupling to rat brain neurons
- 2013
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; :3
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Tidskriftsartikel (refereegranskat)abstract
- Miniature, self-contained biodevices powered by biofuel cells may enable a new generation of implantable, wireless, minimally invasive neural interfaces for neurophysiological in vivo studies and for clinical applications. Here we report on the fabrication of a direct electron transfer based glucose/oxygen enzymatic fuel cell (EFC) from genuinely three-dimensional (3D) nanostructured microscale gold electrodes, modified with suitable biocatalysts. We show that the process underlying the simple fabrication method of 3D nanostructured electrodes is based on an electrochemically driven transformation of physically deposited gold nanoparticles. We experimentally demonstrate that mediator-, cofactor-, and membrane-less EFCs do operate in cerebrospinal fluid and in the brain of a rat, producing amounts of electrical power sufficient to drive a self-contained biodevice, viz. 7 μW cm−2 in vitro and 2 μW cm−2 in vivo at an operating voltage of 0.4 V. Last but not least, we also demonstrate an inductive coupling between 3D nanobioelectrodes and living neurons.
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| 9. |
- Andoralov, Viktor, et al.
(författare)
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Flexible micro(bio)sensors for quantitative analysis of bioanalytes in a nanovolume of human lachrymal liquid
- 2013
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer. - 1618-2642 .- 1618-2650. ; 405:11, s. 3871-3879
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Tidskriftsartikel (refereegranskat)abstract
- A flexible electrochemical micro(bio)sensor has been designed for determination of several biological compounds, specifically, ascorbate, dopamine, and glucose, in human lachrymal liquid (tears). The microsensor for simultaneous determination of ascorbate and dopamine concentrations was based on a gold microwire modified with the tetrathiafulvalen–7,7,8,8-tetracyanoquinodimethane complex as a catalyst. To monitor glucose concentration in tears, glucose dehydrogenase was immobilized on a gold microwire modified with carbon nanotubes and an osmium redox polymer. A capillary microcell was constructed for sampling tears. The cell had a working volume of 60–100 nL with a sampling deviation of 6.7 %. To check if the microcell was properly filled with buffer or tear sample, a control electrode was introduced into the construction. The electrode was used to measure the electrical resistance of a fully filled nanovolume cell. The mechanical flexibility is one of the most important features of the prototype and allowed direct collection of tears with minimized risk of damage to the eye.
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| 10. |
- Andoralov, Victor, et al.
(författare)
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Octaheme nitrite reductase : The mechanism of intramolecular electron transfer and kinetics of nitrite bioelectroreduction.
- 2021
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Ingår i: Bioelectrochemistry. - : Elsevier. - 1567-5394 .- 1878-562X. ; 138
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Tidskriftsartikel (refereegranskat)abstract
- Detailed impedance and voltammetric studies of hexameric octaheme nitrite reductase immobilized on carbon-based nanomaterials, specifically nanotubes and nanoparticles, were performed. Well-pronounced bioelectrocatalytic reduction of nitrite on enzyme-modified electrodes was obtained. Analysis of the impedance data indicated the absence of long-lived intermediates involved in the nitrite reduction. Cyclic voltammograms of biomodified electrodes had a bi-sigmoidal shape, which pointed to the presence of two enzyme orientations on carbon supports. The maximum (limiting) catalytic currents were determined and, by applying the correction by the mixed kinetics equation, the Tafel dependences were plotted for each catalytic wave/each enzyme orientation. Finally, two schemes for the rate-limiting processes during bioelectrocatalysis were proposed, viz. for low- and high-potential orientations.
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