| 1. |
- Falk, Magnus, et al.
(författare)
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Self-powered wireless carbohydrate/oxygen sensitive biodevice based on radio signal transmission
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:10, s. e109104/1-e109104/9
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Tidskriftsartikel (refereegranskat)abstract
- Here for the first time, we detail self-contained (wireless and self-powered) biodevices with wireless signal transmission. Specifically, we demonstrate the operation of self-sustained carbohydrate and oxygen sensitive biodevices, consisting of a wireless electronic unit, radio transmitter and sep. sensing bioelectrodes, supplied with elec. energy from a combined multi-enzyme fuel cell generating sufficient current at required voltage to power the electronics. A carbohydrate/oxygen enzymic fuel cell was assembled by comparing the performance of a range of different bioelectrodes followed by selection of the most suitable, stable combination. Carbohydrates (viz. lactose for the demonstration) and oxygen were also chosen as bioanalytes, being important biomarkers, to demonstrate the operation of the self-contained biosensing device, employing enzyme-modified bioelectrodes to enable the actual sensing. A wireless electronic unit, consisting of a micropotentiostat, an energy harvesting module (voltage amplifier together with a capacitor) and a radio microchip, were designed to enable the biofuel cell to be used as a power supply for managing the sensing devices and for wireless data transmission. The electronic system used required current and voltages greater than 44 μA and 0.57 V, resp. to operate; which the biofuel cell was capable of providing, when placed in a carbohydrate and oxygen contg. buffer. In addn., a USB based receiver and computer software were employed for proof-of concept tests of the developed biodevices. Operation of bench-top prototypes was demonstrated in buffers contg. different concns. of the analytes, showcasing that the variation in response of both carbohydrate and oxygen biosensors could be monitored wirelessly in real-time as analyte concns. in buffers were changed, using only an enzymic fuel cell as a power supply.
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| 2. |
- Mate, Diana, et al.
(författare)
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Blood tolerant laccase by directed evolution
- 2013
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Ingår i: Chemistry and Biology. - : Elsevier. - 1074-5521 .- 1879-1301. ; 20:2, s. 223-231
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Tidskriftsartikel (refereegranskat)abstract
- High-redox potential laccases are powerful biocatalysts with a wide range of applications in biotechnol. We have converted a thermostable laccase from a white-rot fungus into a blood tolerant laccase. Adapting the fitness of this laccase to the specific compn. of human blood (above neutral pH, high chloride concn.) required several generations of directed evolution in a surrogate complex blood medium. Our evolved laccase was tested in both human plasma and blood, displaying catalytic activity while retaining a high redox potential at the T1 copper site. Mutations introduced in the second coordination sphere of the T1 site shifted the pH activity profile and drastically reduced the inhibitory effect of chloride. This proof of concept that laccases can be adapted to function in extreme conditions opens an array of opportunities for implantable nanobiodevices, chem. syntheses, and detoxification.
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| 3. |
- Mate, Diana, et al.
(författare)
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Switching from blue to yellow : altering the spectral properties of a high redox potential laccase by directed evolution
- 2013
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Ingår i: Biocatalysis and Biotransformation. - : Informa Healthcare. - 1024-2422 .- 1029-2446. ; 31:1, s. 8-21
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Tidskriftsartikel (refereegranskat)abstract
- During directed evolution to functionally express the high redox potential laccase from the PM1 basidiomycete in Saccharomyces cerevisiae, the characteristic max. absorption at the T1 copper site (Abs610T1Cu) was quenched, switching the typical blue color of the enzyme to yellow. To det. the mol. basis of this color change, we characterized the original wild-type laccase and its evolved mutant. Peptide printing and MALDI-TOF anal. confirmed the absence of contaminating protein traces that could mask the Abs610T1Cu, while conservation of the redox potential at the T1 site was demonstrated by spectroelectrochem. redox titrns. Both wild-type and evolved laccases were capable of oxidizing a broad range of substrates (ABTS, guaiacol, DMP, synapic acid) and they displayed similar catalytic efficiencies. The laccase mutant could only oxidize high redox potential dyes (Poly R-478, Reactive Black 5, Azure B) in the presence of exogenous mediators, indicating that the yellow enzyme behaves like a blue laccase. The main consequence of over-expressing the mutant laccase was the generation of a six-residue N-terminal acidic extension, which was assocd. with the failure of the STE13 protease in the Golgi compartment giving rise to alternative processing. Removal of the N-terminal tail had a neg. effect on laccase stability, secretion and its kinetics, although the truncated mutant remained yellow. The results of CD spectra anal. suggested that polyproline helixes were formed during the directed evolution altering spectral properties. Moreover, introducing the A461T and S426N mutations in the T1 environment during the first cycles of lab. evolution appeared to mediate the alterations to Abs610T1Cu by affecting its coordinating sphere. This laccase mutant is a valuable departure point for further protein engineering towards different fates.
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| 4. |
- Pita, Marcos, et al.
(författare)
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Bioelectrochemical Oxidation of Water
- 2014
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 136:16, s. 5892-5895
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Tidskriftsartikel (refereegranskat)abstract
- The electrolysis of water provides a link between elec. energy and hydrogen, a high energy d. fuel and a versatile energy carrier, but the process is very expensive. Indeed, the main challenge is to reduce energy consumption for large-scale applications using efficient renewable catalysts that can be produced at low cost. Here we present for the first time that laccase can catalyze electrooxidn. of H2O to mol. oxygen. Native and lab.-evolved laccases immobilized onto electrodes serve as bioelectrocatalytic systems with low overpotential and a high O2 evolution ratio against H2O2 prodn. during H2O electrolysis. Our results open new research ground on H2O splitting, as they overcome serious practical limitations assocd. with artificial electrocatalysts currently used for O2 evolution.
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