| 1. |
- Christenson, Andreas, et al.
(författare)
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Direct electron transfer between ligninolytic redox enzymes and electrodes
- 2004
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Ingår i: Electroanalysis. - : Wiley. - 1040-0397 .- 1521-4109. ; 16:13-14, s. 1074-1092
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Forskningsöversikt (refereegranskat)abstract
- The electrochemistry of the ligninolytic redox enzymes, which include lignin peroxidase, manganese peroxidase and laccase and possibly also cellobiose dehydrogenase, is reviewed and discussed in conjunction with their basic biochemical characteristics. It is shown that long-range electron transfer between these enzymes and electrodes can be established and their ability to degrade lignin through a direct electron transfer mechanism is discussed.
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| 2. |
- 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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| 3. |
- Ferapontova, Elena, et al.
(författare)
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Direct electrochemistry of proteins and enzymes
- 2005
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Ingår i: Electrochemistry of nucleic acids and proteins : towards electrochemical sensors for genomic and proteomics. - 044452150X
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
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| 4. |
- Nistor, Catalin, et al.
(författare)
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In-field monitoring of cleaning efficiency in waste water treatment plants using two phenol-sensitive biosensors
- 2002
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Ingår i: Analytica Chimica Acta. - 1873-4324. ; 456:1, s. 3-17
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Tidskriftsartikel (refereegranskat)abstract
- Two amperometric biosensors based on the enzymes cellobiose dehydrogenase (CDH) and quinoprotein-dependent glucose dehydrogenase (GDH), have been applied for monitoring the phenolic content in water samples, collected at different stages of a waste water treatment process, thus representing different cleaning levels of two waste water treatment plants (WWTPs). The biosensor measurements were performed in-field, compared with the results obtained by liquid chromatography-mass spectrometry and were further correlated with the cleaning efficiencies of the WWTPs. The effect of several potentially interfering compounds on the sensor response was also studied. The general purpose of the study was to evaluate the potential use of biosensors, not as quantitative tools for phenol analysis, but rather as screening tools indicating a certain trend, i.e. compounds present or not present, and potential correlation with sample toxicity. It was found that the biosensors and LC-MS results were not quantitatively comparable, however, both sensors could follow the decrease of the phenol content from the influent, primary treated and effluent waters. In addition, the correlation between biosensor inhibition and sample toxicity is discussed.
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| 5. |
- Stoica, Leonard, et al.
(författare)
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Biosensor based on cellobiose dehydrogenase for detection of catecholamines
- 2004
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 76:16, s. 4690-4696
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Tidskriftsartikel (refereegranskat)abstract
- A cellobiose dehydrogenase (CDH)-modified graphite electrode was designed for amperometric detection of catecholamines in the flow injection mode, by their recycling between the graphite electrode (+300 mV vs AgAgCl) and the reduced FAD cofactor of adsorbed CDH, resulting in an amplified response signal. The high efficiency of the enzyme-catecholamine reaction leads to a detection limit below 1 nM and a sensitivity of 15.8 A(.)M(-1.)cm(2) 2 (1150 nA/muM) for noradrenaline, with a coverage of less than 2.5 mug of CDH adsorbed on the electrode surface (0.073 cm(2)). Working parameters such as pH, cellobiose concentration, carrier buffer, and applied potential were optimized, using hydroquinone as a model analyte. The sensitivity, linear range, and amplification factor can be modulated by the steady-state concentration of cellobiose in the flow buffer. The response of the sensor decreases only 2% when run continuously for 4 h in the flow injection mode. The response peak maximum is obtained within 6 s at a flow rate of 0.5 mL/min, representing the time of the entire sample segment to pass the electrode. CDH enzymes from Phanerochaete chrysosporium and Sclerotium rolfsii were investigated, providing different characteristics of the sensor, with sensors made with CDH from P. chrysosporium being the better ones.
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| 6. |
- Stoica, Leonard, et al.
(författare)
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Direct electron transfer - A favorite electron route for cellobiose dehydrogenase (CDH) from Trametes villosa. Comparison with CDH from Phanerochaete chrysosporium
- 2006
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:25, s. 10801-10806
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents some functional differences as well as similarities observed when comparing the newly discovered cellobiose dehydrogenase (CDH) from Trametes Villosa (T.v) with the well-characterized one from Phanerochaete chrysosporium (P.c.). The enzymes were physically adsorbed on spectrographic graphite electrodes placed in an amperometric flow through cell connected to a flow system. In the case of T.v.-CDH-modified graphite electrodes, a high direct electron transfer (DET) current was registered at the polarized electrode in the presence of the enzyme substrate reflecting a very efficient internal electron transfer (IET) process between the reduced FAD-cofactor and the oxidized heme-cofactor. In the case of P.c.-CDH-modified graphite electrodes, the DET process is not as efficient, and the current will greatly increase in the presence of a mediator (mediated electron transfer, MET). As a consequence, when comparing the two types of enzyme-modified electrodes an inverted DET/MET ratio for T.v.-CDH is shown, in comparison with P.c.-CDH. The rates of the catalytic reaction were estimated to be comparable for both enzymes, by measuring the combined DET + MET currents. The inverted DET/MET ratio for T.v.-CDH-modified electrodes might suggest that probably there is a better docking between the two domains of this enzyme and that the linker region of P.c.-CDH might have an active role in modulating the rate of the IET (by changing the interdomain distance), with respect to pH. Based on the new properties of T.v.-CDH emphasized in the present study, an analytical application of a third-generation biosensor for lactose was recently published.
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| 7. |
- Stoica, Leonard, et al.
(författare)
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Electrochemical evidence of self-substrate inhibition as functions regulation for cellobiose dehydrogenase from Phanerochaete chrysosporium
- 2009
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Ingår i: Bioelectrochemistry. - : Elsevier. - 1567-5394 .- 1878-562X. ; 76:1-2, s. 42-52
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Tidskriftsartikel (refereegranskat)abstract
- The reaction mechanism of cellobiose dehydrogenase (CDH) from Phanerochaete chrysosporium, adsorbed on graphite electrodes, was investigated by following its catalytic reaction with cellobiose registered in both direct and mediated electron transfer modes between the enzyme and the electrode. A wall-jet flow through amperometric cell housing the CDH-modified graphite electrode was connected to a single line flow injection system. In the present study, it is proven that cellobiose, at concentrations higher than 200 μM, competes for the reduced state of the FAD cofactor and it slows down the transfer of electrons to any 2e−/H+ acceptors or further to the heme cofactor, via the internal electron transfer pathway. Based on and proven by electrochemical results, a kinetic model of substrate inhibition is proposed and supported by the agreement between simulation of plots and experimental data. The implications of this kinetic model, called pseudo-ping-pong mechanism, on the possible functions CDH are also discussed. The enzyme exhibits catalytic activity also for lactose, but in contrast to cellobiose, this sugar does not inhibit the enzyme. This suggests that even if some other substrates are coincidentally oxidized by CDH, however, they do not trigger all the possible natural functions of the enzyme. In this respect, cellobiose is regarded as the natural substrate of CDH.
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| 8. |
- Stoica, Leonard, et al.
(författare)
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Electrochemical investigation of cellobiose dehydrogenase from new fungal sources on Au electrodes
- 2005
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 20:10, s. 2010-2018
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Tidskriftsartikel (refereegranskat)abstract
- Following previous electrochemical investigations of cellobiose dehydrogenase (CDH), the present investigation reports on the initial screening of the electrochemistry of three new CDHs, two from the white rot basidiomycetes Trametes villosa and Phanerochaete sordida and one from the soft rot ascomycete Myriococcum thermophilum, for their ability to directly exchange electrons with 10 different alkanethiol-modified Au electrodes. Direct electron transfer (DET) between the enzymes and some of the modified Au electrodes was shown, both, in the presence and in the absence of cellobiose. However, the length and the head functionality of the alkanethiols drastically influenced the efficiency of the DET reaction and also influenced the effect of pH on the biocatalyfic/redox currents, suggesting the importance of structural/sequence differences between these CDH enzymes. In this respect, the white rot CDHs exhibit excellent biocatalytic and redox currents, whereas for the soft rot CDH the DET communication is much less efficient. Cyclic voltammograms indicate that the heme domain of the CDHs is the part of the enzymes that most readily exchanges electrons with the electrode. However, for R sordida CDH on 11-mercaptoundecanol or dithiopropionic acid-modified Au electrodes, a second voltammetric wave was noticed suggesting that for some orientations of the enzyme, DET communication with the FAD cofactor can also be obtained. (c) 2004 Elsevier B.V. All rights reserved.
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| 9. |
- Stoica, Leonard
(författare)
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Functional aspects of cellobiose dehydrogenase Applications for biosensor development
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electrochemcial investigations were conducted for elucidating and understanding the relation between the various electron transfer processes occurring in cellobiose dehydrogenase (CDH) bound to an electrode surface. Substrate inhibition caused by cellobiose was proven to act in competition with the electron transfer to a two-electron acceptor and under a partial inhibition mechanism for the internal electron transfer process. The implications of these findings have been discussed in relation to what has been stated previously but also exploited for analytical purposes by adjusting the sensitivity of the CDH based biosensor for catecholamines. Different thiols were used to form self-assembled monolayers (SAM) on gold electrodes and these have been used to electrochemically investigate and characterise the direct electron transfer reaction of CDH from two white-rot fungi (Phanerochaete sordida and Trametes villosa), and one soft-rot fungus (Myriococcum thermophilum) in the absence and presence of cellobiose. The high efficiency of the direct electron transfer between Phanerochaete sordida CDH and Trametes villosa CDH and SAM modified Au electrodes was emphasised, and a potential application of these enzymes was demonstrated by development of a third-generation biosensor for lactose determination. Toxic waste-water quinone type pollutants were also determined using a Phanerochaete chrysosporium CDH based biosensor, working under a mediated electron transfer mechanism.
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| 10. |
- Stoica, Leonard, et al.
(författare)
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Third-generation biosensor for lactose based on newly discovered cellobiose dehydrogenase
- 2006
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 78:2, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- The present paper describes the principle and characteristics of a biosensor for lactose based on a third-generation design involving cellobiose dehydrogenase. As resulted from a previous comparative study (submitted manuscript), the novelty of this lactose biosensor is based on highly efficient direct electron transfer between two newly discovered cellobiose dehydrogenases (CDH), from the white rot fungi Trametes villosa and Phanerochaete sordida, and a solid spectrographic graphite electrode. CDH was immobilized on the electrode surface (0.073 cm(2)) by simple physical adsorption, and the CDH-modified electrode was next inserted into a wall-jet amperometric cell connected on-line to a flow injection setup (0.5 mL(.)min(-1)). The P. sordida CDH-based lactose biosensor, proved to be the better one, has a detection limit for lactose of 1 mu M, a sensitivity of 1100 mu A(.)mM(-1.)cm(-2), a response time of 4 s (the time required to obtain the maximum peak current), and a linear range from 1 to 100 mu M lactose (correlation coefficient 0.998). The simplicity of construction and analytical characteristics make this CDH-based lactose biosensor an excellent alternative to previous lactose biosensors reported in the literature or commercially available. The CDH-lactose sensor was used to quantify the content of lactose in pasteurized milk, buttermilk, and low-lactose milk, using the standard addition method. No effects of the samples matrixes were observed. The operational stability of the sensor was tested for 11 h by continuous injection of 100 mu M lactose (290 injections). The final signal of the sensor was maintained at 98% of its initial signal, with a low standard deviation of 1.72 (RSD 2.41%).
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