liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 14 of 14
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Björk, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. University of Nacl Rio Cuarto, Argentina.
    Militello, Maria P.
    University of Nacl Rio Cuarto, Argentina.
    Tamborini, Luciano H.
    University of Nacl Rio Cuarto, Argentina.
    Coneo Rodriguez, Rusbel
    University of Nacl Rio Cuarto, Argentina.
    Planes, Gabriel A.
    University of Nacl Rio Cuarto, Argentina.
    Acevedo, Diego F.
    University of Nacl Rio Cuarto, Argentina; University of Nacl Rio Cuarto, Argentina.
    Sergio Moreno, M.
    Consejo Nacl Invest Cient and Tecn, Argentina.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Barbero, Cesar A.
    University of Nacl Rio Cuarto, Argentina.
    Mesoporous silica and carbon based catalysts for esterification and biodiesel fabrication-The effect of matrix surface composition and porosity2017In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 533, p. 49-58Article in journal (Refereed)
    Abstract [en]

    The effects of catalyst matrix porosity composition on the catalytic performance have been studied using sulfonated mesoporous SBA-15 silica. The matrix was sulfonated with three different methods grafting, in situ oxidation, and carbon infiltration. Additionally, unordered sulfonated mesoporous carbon, and the commercial catalysts Amberlite IR-120 and Nafion 117 were tested. The catalytic performance was evaluated in a Fischer esterification using acetic acid and ethanol, as well as in a transesterification of triglycerides (sunflower oil) and ethanol to produce biodiesel. The study shows that for long carbon chains, the effective wetting of the porous catalyst matrix by the reactants is most important for the catalytic efficiency, while for shorter carbon chain, the mass transport of the reagents trough the porous structure is more important. The catalysts were analysed using electron microscopy and physisorption. The study shows that the reactions are faster with carbon infiltrated materials than the silica materials due to a higher concentration of sulfonic groups linked to the carbon. The in situ functionalized SBA-15 is a more efficient catalyst compared to the post grafted one. All the synthesized catalysts outperform the commercial ones in both reactions in terms of conversion. (C) 2017 Elsevier B.V. All rights reserved.

    The full text will be freely available from 2019-01-10 10:33
  • 2.
    Brusved Andersson, Linnea
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Future Strategy for Wastewater Treatment at Skärblacka Mill2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To replace nonrenewable materials, glass, plastics and metals, at the market the production of the environmental friendly material paper needs to increase numerously. An increased paper production leads to an enlarged wastewater flow at the paper mill and thereby higher surface load in the biologicalwastewater plant. Higher surface load in turn, leads to lower efficiency and higher emissions. To be able to increase the capacity of the paper production, the wastewater flow to the biological wastewater treatment needs to be decreased.

    In this thesis, the wastewater at Skärblacka mill has been studied to identify how to increase the production without increasing the flow of wastewater to the biological wastewater treatment. Different wastewater has been studied to identify sufficient clean wastewater flows that today are directed to the biological wastewater treatment.

    The outcome of this thesis is that up to 600 m3/h wastewater could be removed from the biological wastewater treatment due to sufficiently high purity. This outcome is primarily based on measurements of the emission parameters, Total Organic Carbon, Suspended Solids, Total Phosphorus and Total Nitrogen and the calculation of PEC/PNEC, environmental assessment, for the chemicals in the wastewater.

    The unload of up to 600 m3/h will contribute to an increased efficiency in the biological wastewater treatment and thereby lower emissions. Increased efficiency and lower levels of emissions will in turn contribute to a possibility to increase the paper production at Skärblacka mill without interfering withenvironmental demands.

  • 3.
    Gunnarsson, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Titanium oxide nanoparticle production using high power pulsed plasmas2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis covers fundamental aspects of process control when growing titanium oxide nanoparticles in a reactive sputtering process. It covers the influence of oxygen containing gas on the oxidation state of the cathode from which the growth material is ejected, as well as its influence on the particles oxidation state and their nucleation. It was found that a low degree of reactive gases was necessary for nanoparticles of titanium to nucleate. When the oxygen gas was slightly increased, the nanoparticle yield and particle oxygen content increased. A further increase caused a decrease in particle yield which was attributed to a slight oxidation of the cathode. By varying the oxygen flow to the process, it was possible to control the oxygen content of the nanoparticles without fully oxidizing the cathode. Because oxygen containing gases such as residual water vapour has a profound influence on nanoparticle yield and composition, the deposition source was re-engineered to allow for cleaner and thus more stable synthesis conditions.

    The size of the nanoparticles has been controlled by two means. The first is to change electrical potentials around the growth zone, which allows for nanoparticle size control in the order of 25-75 nm. This size control does not influence the oxygen content of the nanoparticles. The second means of size control investigated was by increasing the pressure. By doing this, the particle size can be increased from 50 – 250 nm, however the oxygen content also increases with pressure. Different particle morphologies were found by changing the pressure. At low pressures, mostly spherical particles with weak facets were produced. As the pressure increased, the particles got a cubic shape. At higher pressures the cubic particles started to get a fractured surface. At the highest pressure investigated, the fractured surface became poly-crystalline, giving a cauliflower shaped morphology.

    List of papers
    1. Synthesis of titanium-oxide nanoparticles with size and stoichiometry control
    Open this publication in new window or tab >>Synthesis of titanium-oxide nanoparticles with size and stoichiometry control
    2015 (English)In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 17, no 9, p. 353-Article in journal (Refereed) Published
    Abstract [en]

    Ti-O nanoparticles have been synthesized via hollow cathode sputtering in an Ar-O-2 atmosphere using high power pulsing. It is shown that the stoichiometry and the size of the nanoparticles can be varied independently, the former through controlling the O-2 gas flow and the latter by the independent biasing of two separate anodes in the growth zone. Nanoparticles with diameters in the range of 25-75 nm, and with different Ti-O compositions and crystalline phases, have been synthesized.

    Place, publisher, year, edition, pages
    Springer Verlag (Germany), 2015
    Keywords
    Titanium dioxide; TiO2; Reactive sputtering; Size control; Composition control; Gas flow sputtering; Aerosols
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-121300 (URN)10.1007/s11051-015-3158-3 (DOI)000360245300002 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg foundation [KAW 2014.0276]; Swedish Research Council via the Linkoping Linneaus Environment LiLi-NFM [2008-6572]

    Available from: 2015-09-16 Created: 2015-09-14 Last updated: 2017-12-21
  • 4.
    Lai, Kwok Kei
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, P. R. China .
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, P. R. China .
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    High efficiency single-step biomaterial-based microparticle fabrication via template-directed supramolecular coordination chemistry2016In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 18, no 6, p. 1715-1723Article in journal (Refereed)
    Abstract [en]

    Biomaterial-based microparticles have attracted much attention for medical and biological applications such as pharmaceutics, bioseparation and cosmetics. Emerging technologies enable versatile and facile fabrication of microparticles, with key features being purity, precise size control, mild preparation conditions and minimal processing. Here, an innovative approach combining template synthesis, biomolecule assembly and partial-purification within a single step for high efficiency fabrication of pure biomaterial-based microparticles is reported. This concept is based on facile co-precipitation of biomolecules within CaCO3 templates and simultaneous crosslinking of entrapped biomolecules via Ca2+ driven supramolecular coordination chemistry, followed by template removal. Carbohydrate (alginate) and proteins (casein and fresh milk) are used as models of biomolecules. The process driven by selective crosslinking automatically excludes non-specific materials from the template and thus provides the additional function of partial-purification, as demonstrated using highly complexed fresh milk. This green approach to fabrication of biomaterial-based microparticles offers three critical advantages (i) mild conditions to preserve the chemical and secondary structures of biomolecules; (ii) single processing step to facilitate scale-up production; and (iii) partial-purification without the need for upstream raw material purification. This innovative approach not only addresses fundamental issues in fabrication techniques, but also marks progress in energy and environmental conservation during manufacturing processes.

  • 5.
    Lassebro, Joakim
    Linköping University, Department of Physics, Chemistry and Biology.
    Förstudie till rengöringsvalidering av produktionssystem för handdesinfektionsmedlet AHD 20002017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    When manufacturing products for medicinal use it is essential to reduce the level of cross-contamination. By carrying out a cleaning validation study the effectiveness of the cleaning process is evaluated to see what needs to be done to reach the criteria that are demanded.

    The main purpose of this thesis has been to plan and execute a pilot study for a cleaning validation of the production system where AHD 2000, a hand disinfection product, is being produced.

    A physical inspection of the production system was undertaken and several so called critical areas where pointed out where it is possible that the cleaning process varies in its effectiveness. To evaluate its effectiveness three different sampling methods was undertaken; a swab test, a rinsing test and a visual inspection. To evaluate these tests, analysis of the samples from the swab test and rinse test was studied where the level of total organic carbon (TOC) and chemical oxygen demand (COD) of the samples where measured. Acceptance criteria for the two sampling methods were calculated in order to know which levels of maximum carry over from a previous product that could be accepted. The accepted limits are based on a general limit, usually these limits are in the range 10-500 ppm of a previously manufactured batch. For the visual inspection a physical exam of the critical points was performed where signs of visible residue were noted.

    The results from the swab test for all critical areas were below the acceptance criteria and thus the criteria for the swab test was accepted. As for the rinsing test the results were slightly above the acceptance criteria but were regarded as acceptable. The visual inspection showed no signs of visible traces of product.

    Based on the results, the three criteria are therefore satisfied and the cleaning process was regarded to be effective enough to remove traces from a previously produced product.

  • 6.
    Malmborg, Jonas
    et al.
    National Forens Centre, Chemistry and Technology, SE-58194 Linkoping, Sweden.
    Nordgaard, Anders
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, Faculty of Arts and Sciences. National Forens Centre, Chemistry and Technology, SE-58194 Linkoping, Sweden.
    Forensic characterization of mid-range petroleum distillates using light biomarkers2016In: Environmental Forensics, ISSN 1527-5922, E-ISSN 1527-5930, Vol. 17, no 3, p. 244-252Article in journal (Refereed)
    Abstract [en]

    Due to oil refining, commonly used higher boiling biomarkers for oil-source correlation are absent from mid-range petroleum distillates, while lighter biomarkers are concentrated in such products. This study evaluated 63 diagnostic ratios of light biomarkers such as bicyclic sesquiterpanes, diamondoids, and lighter aromatic compounds using 70 diesel oil samples obtained from three Swedish refineries and local gas stations, mostly over a six-month period in 2015. On the basis of their diagnostic power and partial correlation coefficients, a set of 24 ratios is suggested for oil-source correlation of lighter products. The frequency of false positives for this set was determined to be approximately 0.1%. It should be emphasized that in the event of an oil spill, diesel oils are rapidly influenced by weathering and many of the ratios will be affected.

  • 7.
    Melianas, Armantas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Pranculis, Vytenis
    Center for Physical Sciences and Technology Savanoriu, Lithuania.
    Xia, Yuxin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Felekidis, Nikolaos
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gulbinas, Vidmantas
    Center for Physical Sciences and Technology Savanoriu, Lithuania.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Photogenerated Carrier Mobility Significantly Exceeds Injected Carrier Mobility in Organic Solar Cells2017In: Advanced Energy Materials, ISSN 1614-6840, Vol. 7, no 9, article id 1602143Article in journal (Refereed)
    Abstract [en]

    Charge transport in organic photovoltaic (OPV) devices is often characterized by space-charge limited currents (SCLC). However, this technique only probes the transport of charges residing at quasi-equilibrium energies in the disorder-broadened density of states (DOS). In contrast, in an operating OPV device the photogenerated carriers are typically created at higher energies in the DOS, followed by slow thermalization. Here, by ultrafast time-resolved experiments and simulations it is shown that in disordered polymer/fullerene and polymer/polymer OPVs, the mobility of photogenerated carriers significantly exceeds that of injected carriers probed by SCLC. Time-resolved charge transport in a polymer/polymer OPV device is measured with exceptionally high (picosecond) time resolution. The essential physics that SCLC fails to capture is that of photo­generated carrier thermalization, which boosts carrier mobility. It is predicted that only for materials with a sufficiently low energetic disorder, thermalization effects on carrier transport can be neglected. For a typical device thickness of 100 nm, the limiting energetic disorder is σ ≈71 (56) meV for maximum-power point (short-circuit) conditions, depending on the error one is willing to accept. As in typical OPV materials the disorder is usually larger, the results question the validity of the SCLC method to describe operating OPVs.

  • 8.
    Mihon, Mirela
    et al.
    University of Politehn Bucuresti, Romania; Horia Hulubei National Institute Phys and Nucl Engn, Romania.
    Stelian Tuta, Catalin
    Horia Hulubei National Institute Phys and Nucl Engn, Romania.
    Catrinel Ion, Alina
    University of Politehn Bucuresti, Romania.
    Koziorowski, Jacek
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Niculae, Dana
    Horia Hulubei National Institute Phys and Nucl Engn, Romania.
    Lavric, Vasile
    University of Politehn Bucuresti, Romania.
    Draganescu, Doina
    Horia Hulubei National Institute Phys and Nucl Engn, Romania; Carol Davila University of Medical and Pharm, Romania.
    INFLUENCE OF THE SEPARATION PARAMETERS APPLIED FOR DETERMINATION OF IMPURITIES FDG AND CLDG2017In: Farmacia, ISSN 0014-8237, E-ISSN 2065-0019, Vol. 65, no 1, p. 153-158Article in journal (Refereed)
    Abstract [en]

    2-fluoro-2-deoxy-D-glucose (FDG) and 2-chloro-2-deoxy-D-glucose (CIDG) are chemical impurities found in the 2-[F-18]fluoro-2-deoxy-D-glucose products (F-18-FDG). The objective of this study was to find the best condition for the separation of FDG and CIDG, evaluating different columns under various operating conditions. Chromatographic parameters such as column temperature, composition and flow rate of the mobile phase were the independent variables used in the optimization process. The optimized method was validated and validation results showed a good accuracy, repeatability and reproducibility.

  • 9.
    Roch, Patricia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, Faculty of Science & Engineering.
    Mandenius, Carl-Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, Faculty of Science & Engineering.
    On-line monitoring of downstream bioprocesses2016In: CURRENT OPINION IN CHEMICAL ENGINEERING, ISSN 2211-3398, Vol. 14, p. 112-120Article in journal (Refereed)
    Abstract [en]

    Downstream bioprocessing can benefit significantly from using on-line monitoring methods for surveillance, control and optimisation. Timely information on critical operational and product quality parameters provided by on-line monitoring may contribute to high product quality, more efficient process operation and better production economy. Here, recent advances in analytical techniques and tools are critically reviewed and assessed based on their capability to meet typical needs and requirements in the biotechnology industry. Soft sensors, which merge the signals generated from on-line monitoring devices into mathematical models, are highlighted for accessing critical information in downstream processing.

    The full text will be freely available from 2018-10-06 14:59
  • 10.
    Seifeddine, Salem
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Characteristics of cast aluminium-silicon alloys: microstructures and mechanical properties2006Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Applications of aluminium alloys are spreading in many industrial fields due to the excellent combination of castability, mechanical performance and lightness assured by such material. This project aims to establish a methodology in bringing the foundry process closer to the casting designer, and thereby leading to a more reliable and more optimised design. Improvement in the degree of integration between processing, metallurgical and mechanical properties of cast aluminium alloys will lead to a shorter lead-time from the very first design attempt, and sounder components, both of which strengthen the competitiveness of the material and the foundry industry.

    The microstructural features and mechanical properties of cast aluminium alloys are sensitive to composition, melt treatment, the casting process and formation of defects during mould filling, solidification and post-solidification treatment. The microstructural characteristics and the mechanical properties of A1-Si based alloys have been investigated by studies on various different commercial cast components and through systematically designed casting experiments with alloys containing various Si, Mg, Cu, Fe and Mn concentrations solidified under a wide range of cooling conditions. In this work, a gradient solidification thechnique has been employed, providing samples with a low content of oxide films and few porosity defects and with a well-fed and homogenous microstructure. In such samples the alloy's mechanical properties are determined by the microstructure constituents and not by any defects. The influence of the casting process on the microstructural formations and tensile properties has been thoroughly elucidated. Furthermore, relationships between microstructure characteristics and mechanical properties are assessed and discussed. The results indicate that Mg and Cu, due to the formation of A12Cu and Mg2Si have a significant role on the alloy strength, especially after thermal treatment. Significant advances have been mead in understanding the relationship between Fe and Mn levels and their contribution to the tensile strength. While Fe and its compounds, particularly the A15FeSi-needles, adversely influence the ultimate tensile strength and ductility, Mn has been found to not fully neutralize the deleterious character of iron, and especially the influence it has on ductility.

    Algorithms to predict the micorstructural parameters such as porosity, grain size, the volume fraction of different phases, especially A12Cu and Mg2Si, and their influence on the tensile strength, have been developed. The relationships developed between process, microstructure and mechanical properties have been implemented in commercial simulation software.

  • 11.
    Sekretaryova, Alina
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Facilitating electron transfer in bioelectrocatalytic systems2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bioelectrocatalytic systems are based on biological entities, such as enzymes, whole cells, parts of cells or tissues, which catalyse electrochemical processes that involve the interaction between chemical change and electrical energy. In all cases, biocatalysis is implemented by enzymes, isolated or residing inside cells or part of cells. Electron transfer (ET) phenomena, within the protein molecules and between biological redox systems and electronics, enable the development of various bioelectrocatalytic systems, which can be used both for fundamental investigations of enzymatic biological processes by electrochemical methods and for applied purposes, such as power generation, bioremediation, chemical synthesis and biosensing.

    Electrical communication between the biocatalyst’s redox centre and an electrode is essential for the functioning of the system. This can be established using two main mechanisms: indirect ET and direct ET. The efficiency of the ET influences important parameters such as the turnover rate of the biocatalyst, the generated current density and partially the stability of the system, which in their turn determine response time, sensitivity, detection limit and operational stability of biosensing devices or the power densities and current output of biofuel cells, and hence should be carefully considered when designing bioelectrocatalytic systems.

    This thesis focuses on approaches that facilitate ET in bioelectrocatalytic systems based on indirect and direct ET mechanisms. Both fundamental aspects of ET in bioelectrocatalytic systems and applications of such systems for biosensing and power generation are considered. First, a new hydrophobic mediator for oxidases – unsubstituted phenothiazine and its improved ET properties in comparison with commonly used mediators are discussed. Application of the mediator in electrochemical biosensors is demonstrated by glucose, lactate and cholesterol sensing. Utilisation of mediated biocatalytic cholesterol oxidation, as the anodic reaction for the construction of a biofuel cell acting as a power supply and an analytical device at the same time, is investigated to deliver a selfpowered biosensor. Also the enhancement of mediated bioelectrocatalysis by employment of microelectrodes as a transducer is examined. The effect of surface roughness on the current response of the microelectrodes under conditions of convergent diffusion is considered. The applicability of the laccase-based system for total phenol analysis of weakly supported water is demonstrated. Finally, a new electrochemical approach derived from collision-based electrochemistry applicable for examination of the ET process of a single enzyme molecule is described.

    All together, the results presented in this thesis contribute to the solution of the ‘electronic coupling problem’, arising when interfacing biomolecules with electronics and limiting the performance of bioelectrocatalytic systems in specific applications. The developed methods to facilitate ET will hopefully promote future biosensing devices and biofuel cells. I believe the new approach for investigation of ET processes at a single enzyme molecule will complement existing single molecule techniques, giving further insights into enzymatic ET mechanisms at the molecular level and filling the gap between fundamental understanding of biocatalytic processes and their potential for bioenergy production.

    List of papers
    1. Bioelectrocatalytic systems for health applications
    Open this publication in new window or tab >>Bioelectrocatalytic systems for health applications
    2016 (English)In: Biotechnology Advances, ISSN 0734-9750, E-ISSN 1873-1899, Vol. 34, no 3, p. 177-197Article, review/survey (Refereed) Published
    Abstract [en]

    We present a brief overview of bioelectrocatalytic devices for in vitro health applications, including food safety and environmental analysis, focusing on microelectrode- and microfluidic-based biosensors, paper-based point-of-care devices and wearable biosensors. The main hurdles and future perspectives are discussed. We then consider the role of electron transfer between a biocatalyst and an electrode in biosensor design. Brief descriptions of indirect, direct and mediated mechanisms are given. The principal strategies, as well as recent developments for modulation of electron transfer in biocatalytic systems are summarised. In conclusion, we highlight some of the challenges associated with improving these redox systems.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keywords
    Direct electron transfer; Mediated electron transfer; Immobilisation; Microbiosensor; Nanobiosensor; Paper-based biosensor; Wearable biosensor; Self-powered biosensor
    National Category
    Bioinformatics and Systems Biology
    Identifiers
    urn:nbn:se:liu:diva-123688 (URN)10.1016/j.biotechadv.2015.12.005 (DOI)000375500700004 ()26724183 (PubMedID)
    Available from: 2016-01-08 Created: 2016-01-08 Last updated: 2017-12-01Bibliographically approved
    2. Reagentless Biosensor Based on Glucose Oxidase Wired by the Mediator Freely Diffusing in Enzyme Containing Membrane
    Open this publication in new window or tab >>Reagentless Biosensor Based on Glucose Oxidase Wired by the Mediator Freely Diffusing in Enzyme Containing Membrane
    Show others...
    2012 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 84, no 3, p. 1220-1223Article in journal (Refereed) Published
    Abstract [en]

    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.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2012
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-112343 (URN)10.1021/ac203056m (DOI)22206508 (PubMedID)
    Available from: 2014-11-24 Created: 2014-11-24 Last updated: 2017-12-05Bibliographically approved
    3. Unsubstituted phenothiazine as a superior water-insoluble mediator for oxidases
    Open this publication in new window or tab >>Unsubstituted phenothiazine as a superior water-insoluble mediator for oxidases
    Show others...
    2014 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 53, p. 275-282Article in journal (Refereed) Published
    Abstract [en]

    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.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Phenothiazine; Electron transfer mediator; Enzyme biosensor; Glucose oxidase; Lactate oxidase; Cholesterol oxidase
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-100391 (URN)10.1016/j.bios.2013.09.071 (DOI)000329881100044 ()
    Available from: 2013-11-05 Created: 2013-11-05 Last updated: 2017-12-06Bibliographically approved
    4. Cholesterol Self-Powered Biosensor
    Open this publication in new window or tab >>Cholesterol Self-Powered Biosensor
    Show others...
    2014 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 86, no 19, p. 9540-9547Article in journal (Refereed) Published
    Abstract [en]

    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.

    Place, publisher, year, edition, pages
    American Chemical Society, 2014
    National Category
    Physical Sciences Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-112176 (URN)10.1021/ac501699p (DOI)000343017100031 ()25164485 (PubMedID)
    Note

    Funding Agencies|Swedish research council Formas; research centre Security Link; Swedish Institute

    Available from: 2014-11-18 Created: 2014-11-18 Last updated: 2017-12-05
    5. Arrays of Screen-Printed Graphite Microband Electrodes as a Versatile Electroanalysis Platform
    Open this publication in new window or tab >>Arrays of Screen-Printed Graphite Microband Electrodes as a Versatile Electroanalysis Platform
    Show others...
    2014 (English)In: ChemElectroChem, ISSN 2196-0216, Vol. 1, no 4, p. 755-762Article in journal (Refereed) Published
    Abstract [en]

    Arrays of microband electrodes were developed by screen printing followed by cutting, which enabled the realization of microband arrays at the cut edge. The microband arrays of different designs were characterized by physical and electro-chemical methods. In both cases, the methods showed that the microband width was around 5 mm. Semi-steady-state cyclic voltammetry responses were observed for redox probes, and chronocoulometric measurements showed the establishment of convergent diffusion regimes characterized by current densities similar to those of a single microelectrode. The analytical performance of the electrode system and its versatility were illustrated with two electrochemical assays: detection of ascorbic acid through direct oxidation and a mediated glucose biosensor fabricated by dip coating. Due to convergent mass transport, both systems showed an enhancement in their analytical characteristics. The developed approach can be adapted to automated electrode recovery.

    Place, publisher, year, edition, pages
    Wiley, 2014
    Keywords
    graphite screen printing; microarrays; microband; sensors; voltammetry
    National Category
    Physical Sciences Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-109289 (URN)10.1002/celc.201300204 (DOI)000338296100010 ()
    Available from: 2014-08-11 Created: 2014-08-11 Last updated: 2017-11-03Bibliographically approved
    6. Evaluation of the electrochemically active surface area of microelectrodes by capacitive and faradaic currents
    Open this publication in new window or tab >>Evaluation of the electrochemically active surface area of microelectrodes by capacitive and faradaic currents
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Two methods to estimate the electrochemically active surface area (EASA) of microelectrodes were compared. One is based on electrocapacitive measurements and the other on faradaic measuements. A systematic study revealed a strong influence of the surface roughness and the electrolyte concentration on the EASA of microelectrodes estimated from the electrocapacitive measurements, yielding a lack of reliability compared to the faradaic method.

    Keywords
    Electrochemically active surface area, microelectrode, microband, roughness, capacitive process, faradaic process
    National Category
    Chemical Sciences Chemical Engineering Chemical Process Engineering
    Identifiers
    urn:nbn:se:liu:diva-125240 (URN)
    Available from: 2016-02-17 Created: 2016-02-17 Last updated: 2017-11-03Bibliographically approved
    7. Total phenol analysis of weakly supported water using a laccase-based microband biosensor.
    Open this publication in new window or tab >>Total phenol analysis of weakly supported water using a laccase-based microband biosensor.
    Show others...
    2016 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 907, p. 45-53Article in journal (Refereed) Published
    Abstract [en]

    The monitoring of phenolic compounds in wastewaters in a simple manner is of great importance for environmental control. Here, a novel screen printed laccase-based microband array for in situ, total phenol estimation in wastewaters and for water quality monitoring without additional sample pre-treatment is presented. Numerical simulations using the finite element method were utilized for the characterization of micro-scale graphite electrodes. Anodization followed by covalent modification was used for the electrode functionalization with laccase. The functionalization efficiency and the electrochemical performance in direct and catechol-mediated oxygen reduction were studied at the microband laccase electrodes and compared with macro-scale electrode structures. The reduction of the dimensions of the enzyme biosensor, when used under optimized conditions, led to a significant improvement in its analytical characteristics. The elaborated microsensor showed fast responses towards catechol additions to tap water – a weakly supported medium – characterized by a linear range from 0.2 to 10 μM, a sensitivity of 1.35 ± 0.4 A M−1 cm−2 and a dynamic range up to 43 μM. This enhanced laccase-based microsensor was used for water quality monitoring and its performance for total phenol analysis of wastewater samples from different stages of the cleaning process was compared to a standard method.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keywords
    Laccase; microelectrode; microband; electrochemical modeling; total phenol analysis; wastewater
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-123677 (URN)10.1016/j.aca.2015.12.006 (DOI)000368422900005 ()
    Note

    Funding agencies: Swedish research council Formas [245-2010-1062]; research centre Security Link [VINNOVA 2009-00966]; Norrkopings fond for Forskning och Utveckling; VINNOVA

    Available from: 2016-01-07 Created: 2016-01-07 Last updated: 2017-12-01Bibliographically approved
    8. Electrocatalytic Currents from Single Enzyme Molecules
    Open this publication in new window or tab >>Electrocatalytic Currents from Single Enzyme Molecules
    2016 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 8, p. 2504-2507Article in journal (Refereed) Published
    Abstract [en]

    Single molecule enzymology provides an opportunity to examine details of enzyme mechanisms that are not distinguishable in biomolecule ensemble studies. Here we report, for the first time, detection of the current produced in an electrocatalytic reaction by a single redox enzyme molecule when it collides with an ultramicroelectrode. The catalytic process provides amplification of the current from electron-transfer events at the catalyst leading to a measurable current. This new methodology monitors turnover of a single enzyme molecule. The methodology might complement existing single molecule techniques, giving further insights into enzymatic mechanisms and filling the gap between fundamental understanding of biocatalytic processes and their potential for bioenergy production.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2016
    National Category
    Chemical Sciences Chemical Engineering Chemical Process Engineering
    Identifiers
    urn:nbn:se:liu:diva-125241 (URN)10.1021/Jacs.5b13149 (DOI)000371453700011 ()
    Note

    Funding agencies:  Swedish research council Formas [245-2010-1062]; research center Security Link (VINNOVA ) [2009-00966]; Centre in Nano Science and Technology (CeNano, Linkoping University)

    Vid tiden för dispuation förelåg publikationen endast som manuskript

    Available from: 2016-02-17 Created: 2016-02-17 Last updated: 2017-11-30Bibliographically approved
  • 12.
    Sekretaryova, Alina N.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail Yu.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Evaluation of the electrochemically active surface area of microelectrodes by capacitive and faradaic currentsManuscript (preprint) (Other academic)
    Abstract [en]

    Two methods to estimate the electrochemically active surface area (EASA) of microelectrodes were compared. One is based on electrocapacitive measurements and the other on faradaic measuements. A systematic study revealed a strong influence of the surface roughness and the electrolyte concentration on the EASA of microelectrodes estimated from the electrocapacitive measurements, yielding a lack of reliability compared to the faradaic method.

  • 13.
    Sekretaryova, Alina N.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail Yu.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony P.F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Electrocatalytic Currents from Single Enzyme Molecules2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 8, p. 2504-2507Article in journal (Refereed)
    Abstract [en]

    Single molecule enzymology provides an opportunity to examine details of enzyme mechanisms that are not distinguishable in biomolecule ensemble studies. Here we report, for the first time, detection of the current produced in an electrocatalytic reaction by a single redox enzyme molecule when it collides with an ultramicroelectrode. The catalytic process provides amplification of the current from electron-transfer events at the catalyst leading to a measurable current. This new methodology monitors turnover of a single enzyme molecule. The methodology might complement existing single molecule techniques, giving further insights into enzymatic mechanisms and filling the gap between fundamental understanding of biocatalytic processes and their potential for bioenergy production.

  • 14.
    Stenberg, Pontus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Sukkaew, Pitsiri
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Farkas, Ildiko
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Kordina, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Danielsson, Örjan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Silicon Chemistry in Fluorinated Chemical Vapor Deposition of Silicon Carbide2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 5, p. 2711-2720Article in journal (Refereed)
    Abstract [en]

    The use of chlorinated chemical vapor deposition (CVD) chemistry for growth of homoepitaxial layers of silicon carbide (SiC) has diminished the problem of homogenous gas phase nucleation, mainly the formation of Si droplets, in CVD of SiC by replacing Si-Si bonds with stronger Si-Cl bonds. Employing the even stronger Si-F bond could potentially lead to an even more efficient CVD chemistry, however, fluorinated chemistry is very poorly understood for SiC CVD. Here, we present studies of the poorly understood fluorinated CVD chemistry for homoepitaxial SiC layers using SiF4 as Si precursor. We use a combination of experimental growth studies, thermal equilibrium calculations of gas phase composition and quantum chemical computations (i.e. hybrid density functional theory) of the surface chemistry to probe the silicon chemistry in the CVD process. We show that while growth rates on the order of 35 µm/h can be achieved with a fluorinated chemistry, the deposition chemistry is very sensitive to the mass flows of the precursors and not as robust as the chlorinated CVD chemistry which routinely yields 100 µm/h over wide conditions. By using the position for the onset of epitaxial growth along the gas flow direction as a measurable, together with modeling, we conclude that SiF is the main Si growth species with SiHF as a minor Si species contributing to growth.

1 - 14 of 14
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf