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  • 201.
    Ulrich, Christian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Andersson, Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Björefors, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    New Methods in Surface Science and Surface Analysis-Towards Biomimetic Sensing2007In: A Vinnova program conference: Multidisciplinary BIO,2007, 2007Conference paper (Refereed)
    Abstract [en]

            

  • 202.
    Ulrich, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Andersson, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Nyholm, Leif
    Uppsala University.
    Björefors , Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Potential and Current Density Distributions at Electrodes Intended for Bipolar Patterning2009In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, no 1, p. 453-459Article in journal (Refereed)
    Abstract [en]

    This paper deals with the use of reaction gradients on bipolar electrodes for the patterning of electrode surfaces. More specifically, the potential and current density distributions in two setups containing bipolar electrodes were investigated to optimize and design specific gradient geometries. Comparisons with simulations based on simple conductivity models showed a good qualitative agreement, demonstrating that these models could be used to predict bipolar behavior in more complex setups. In conjunction with imaging surface plasmon resonance (iSPR) experiments, the reaction gradients on bipolar electrodes could further be visualized. It was, for example, found that the gradient in potential difference was approximately linearly distributed in the center of the bipolar electrode and that these potential differences could be determined using an ordinary Ag/AgCl reference electrode. The present results thus provide a better understanding of the processes relevant for bipolar patterning. This approach was finally used to generate a circular gradient region in a self-assembled monolayer, thereby showing the possibilities to create interesting substrates for biosensors and microarray applications.

  • 203.
    Ulrich, Christian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Andersson, Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Nyholm, Leif
    Björefors, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Formation and Imaging of Gradients in Electrochemical Reactions and Molecular Films2008In: ESEAC2008 European Society for ElectroAnalytical Chemistry,2008, 2008Conference paper (Other academic)
  • 204.
    Ulrich, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Andersson, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Nyholm, Leif
    Department of Materials Chemistry, Uppsala University, P.O. Box 538, 75121 Uppsala, Sweden.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Formation of Molecular Gradients on Bipolar Electrodes2008In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 47, no 16, p. 3034-3036Article in journal (Refereed)
  • 205.
    Ulrich, Christian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Björefors, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Electrochemistry Combined With Imaging Ellipsometry2006Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Konferensbidrag (i form av Poster) vid "ISE", Edingburgh, Scotland, August

  • 206.
    Ulrich, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Louthander, Dan
    Senset AB, Universitetsvägen 14, SE-583 30 Linköping, Sweden.
    Mårtensson, Per
    Senset AB, Universitetsvägen 14, SE-583 30 Linköping, Sweden.
    Kluftinger, André
    WIKA Alexander Wiegand GmbH & Co. KG, Alexander-Wiegand-Strasse, 63911 Klingenberg, Germany.
    Gawronski, Michael
    WIKA Alexander Wiegand GmbH & Co. KG, Alexander-Wiegand-Strasse, 63911 Klingenberg, Germany.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Evaluation of industrial cutting fluids using electrochemical impedance spectroscopy and multivariate data analysis2012In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 97, p. 468-472Article in journal (Refereed)
    Abstract [en]

    In this paper, we explore the combination of electrochemical impedance spectroscopy (EIS) and multivariate data analysis to evaluate the concentration and pH of an industrial cutting fluid. These parameters are vital for the performance of for instance tooling processes, and an on-line monitoring system would be very beneficial. It is shown that both the total impedance and the phase angle contain information that allows the simultaneous discrimination of the concentration and the pH. The final evaluation was made with a regression model, namely partial least squares (PLS). This approach provided a way to quickly and simply find the correlation between EIS data and the sought parameters. The results from the measurements showed the possibility to predict the concentration and pH level, indicating the potential of this method for on-line measurements.

  • 207.
    Ulrich, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Petersson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Sundgren, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Krantz-Rülcker, Christina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Simultaneous estimation of soot and diesel contamination in engine oil using electrochemical impedance spectroscopy2007In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 127, no 2, p. 613-618Article in journal (Refereed)
    Abstract [en]

    In this paper, we explore the combination of electrochemical impedance spectroscopy and multivariate data analysis to simultaneously predict the concentrations of soot and diesel in engine oil. For this purpose, we use a well defined measurement set-up to minimize interference from ambient noise, and to obtain a large amount of data in a short period of time. An imperative requirement is that soot and diesel affect the impedance in different ways over the employed frequency range. It was, for example, found that diesel had a larger influence at lower frequencies. Using partial least squares modelling we show that it is possible to simultaneously predict the concentrations of both soot and diesel in engine oil. Since the temperature in an engine varies, the influence of the oil temperature is investigated in a preliminary experiment. This study is a part of the development of an electrochemical on-board sensor for real-time monitoring of engine oil.

  • 208.
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Functionalized Nanoparticles for Biomedical Imaging2007In: The 6th KAST-KVA Bilateral Symposium,2007, 2007Conference paper (Other academic)
  • 209.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Ahrén, Maria
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Selegård, Linnéa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Abrikossova, Natalia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Klasson, Anna
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiology . Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Söderlind, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Engström, Maria
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Käll, Per-Olov
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry .
    Functionalized Gd2O3 Nanoparticles to Be used for MRI Contrast Enhancement2008In: AVS,2008, 2008Conference paper (Other academic)
  • 210.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Ahrén, Maria
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Söderlind, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Klasson, Anna
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiology . Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Vahlberg, Cecilia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Petoral, Rodrigo Jr
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Engström, Maria
    Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Clinical and Experimental Medicine, Cell Biology.
    Käll, Per-Olov
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry .
    Functionalized rare earth nanocrystals for MRI contrast enhancement2006In: e-MRS,2006, 2006Conference paper (Other academic)
    Abstract [en]

      

  • 211.
    Uvdal, Kajsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Axelsson, Oskar
    Visualization of Biological Material by the use of Coated Contrast Agents2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

      

  • 212.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Ekeroth, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Konradsson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Tyrosine derivatives assembled on gold2003In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 260, no 2, p. 361-366Article in journal (Refereed)
    Abstract [en]

    Two different tyrosine derivatives, one with the OH group free and one with the OH group phosphorylated, linked to 3-mercaptopropionic acid through an amide bond are adsorbed to gold surfaces. The adsorbates are studied by means of X-ray photoelectron spectroscopy (XPS) and infrared reflection-absorption spectroscopy (IRAS). The techniques are used to investigate the coordination to the surface and the molecular orientation of adsorbates relative to the surface. Molecular surface interactions, causing chemical shifts in the core level XPS spectra of the adsorbates on gold, are investigated using multilayer films as references. Angle-dependent XPS, XPS(T), and IRAS are used to estimate molecular orientation relative to the surface. The tyrosine derivatives adsorb chemically to the surface through the sulfur atoms and highly organized monolayers are formed with the OH and the PO32- exposed to the air/vacuum interface. © 2003 Elsevier Science (USA). All rights reserved.

  • 213.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Engström, Maria
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiology .
    Gadolinium oxide nanoparticles and their utility in selective tissue imaging as well as a cell or molecular analysisPatent (Other (popular science, discussion, etc.))
  • 214.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Engström, Maria
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiology .
    Nanoscale particles made of a transition metal and/or rare earth metal compoundPatent (Other (popular science, discussion, etc.))
    Abstract [en]

       

  • 215.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Engström, Maria
    Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Clinical and Experimental Medicine, Cell Biology.
    Nanoscale particles made of a transition metal and/or rare earth metal compound2004Patent (Other (popular science, discussion, etc.))
    Abstract [en]

     US provinsional application

  • 216.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Petoral, Rodrigo Jr
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Söderlind, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Käll, Per-Olov
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry .
    Konradsson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry .
    Engström, Maria
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Magnetic circular X-ray dichroism of Gd2O3 nano particles2003In: AVS,2003, 2003Conference paper (Other academic)
  • 217.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Sadreev, Almas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Sukhinin, Y
    Thermoactivated desorption of Tricyclohexylphosphine from rhodium2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 115, p. 9513-9519Article in journal (Refereed)
  • 218.
    Uvdal, Kajsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Vikinge, T.P.
    Chemisorption of the dipeptide Arg-Cys on a gold surface and the selectivity of G-protein adsorption2001In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 17, no 6, p. 2008-2012Article in journal (Refereed)
    Abstract [en]

    Arginine-L-cysteine dipeptide adsorbates are used in this study as a model system for G-protein-coupled receptors (GPCRs). An arginine-containing model molecule is chosen because the GPCR a2A has been shown to include an arginine-rich region in the G-protein-binding part of the third intracellular loop, and the role of arginines by means of recognition is believed to exceed their positive charge. The dipeptide Arg-Cys is adsorbed to gold surfaces and the peptide monolayers are characterized. These peptide monolayers are then used for G-protein adsorption experiments to study the molecular interaction and binding. The molecular adsorption, orientation, and chemical binding of the peptide to the surface are studied by X-ray photoelectron spectroscopy and infrared reflection-absorption spectroscopy. A chemical shift in the S(2p) core level spectrum of the peptide adsorbate on gold shows that there is a strong molecular surface interaction consistent with a chemical binding of the peptide to the surface through the sulfur atom. With the cysteine part linked to the surface, the arginine part of the molecule is available for further adsorption processes. Monolayers of Arg-Cys, L-cysteine, and cysteamine are used for G-protein adsorption experiments. Adsorption of human serum albumin and human immunoglobulins on the same monolayers are studied for comparison. The analytical tool is surface plasmon resonance. Two different buffers are used for the adsorption studies, and the influence of buffer composition on protein adsorption is discussed.

  • 219.
    Vahlberg, Cecilia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Phenylboronic ester- and Phenylboronic acid-terminated alkanethiols on Gold SurfacesManuscript (preprint) (Other academic)
    Abstract [en]

    In this work, it is shown that well-organized monolayer of phenylboronic ester-terminated thiol (BOR-Capped) on gold surfaces can be prepared. Our results also show that the BORCapped molecular system can be cleaved directly on the surface, resulting in an unprotected BOR-Uncapped monolayer with the boronic acid functional groups available for dopamine coordination. The monolayers of BOR-Capped and BOR-Uncapped were characterized using infrared spectroscopy, near edge X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, ellipsometry and contact angle goniometry. The X-ray photoelectron spectroscopy results showed that both BOR-Capped and BOR-Uncapped are chemically linked to the gold substrate. According to the infrared spectroscopy results, the main component of the C=O vibrational mode present in the amide moiety is perpendicular oriented relative to the gold surface normal for the BOR-Capped molecular system. The near edge X-ray absorption fine structure spectroscopy resonance peak located at approximately 285 eV, assigned to π* transitions, was used to estimate the average tilt angle of the vector parallel to the π* orbitals of the aromatic ring relative to the gold surface normal. The average tilt angle is estimated to be approximately 63º for BOR-Capped monolayer on gold surfaces. The aromatic ring of the BOR-Uncapped molecule has a more tilted orientation compared to BOR-Capped. The experimental infrared spectroscopy and near edge X-ray absorption fine structure spectroscopy results were supported with theoretical modeling including calculations of vibrational modes and of excitation processes.

  • 220.
    Vahlberg, Cecilia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lindell, Charlotta
    Linköping University, Faculty of Health Sciences.
    Petoral, Rodrigo Jr
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Broo, Klas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    An interaction study of G-protein and Alpha 2A-Adrenergic Receptor derived peptides using Surface Plasmon Resonance Technology2004In: Biological Physics,2004, 2004Conference paper (Other academic)
  • 221.
    Vahlberg, Cecilia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Petoral, Rodrigo Jr
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Carlsson, Andreas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Broo, Klas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Neurotransmitter Derivatives Adsorbed on Gold2007In: IVC-17/ICSS-13 ICNT,2007, 2007Conference paper (Other academic)
  • 222.
    Vahlberg, Cecilia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Skoglund, Caroline
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Uvdal, Jahsa
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    The Structure of Benzenesulfonamide-Terminated Thiol on Gold Surfaces and the Interaction with Carbonic AnhydraseManuscript (preprint) (Other academic)
    Abstract [en]

    A well-structured and robust biomolecular monolayer based upon a benzenesulfonamideterminated alkane thiol, to be used as a model system for molecular recognition processes, was prepared. The benzenesulfonamide-terminated thiol adsorbed onto gold substrates was characterized using X-ray photoelectron spectroscopy, near edge X-ray absorption fine structure spectroscopy, infrared-reflection absorption spectroscopy and ellipsometry. The results showed that the benzenesulfonamide-terminated alkane thiol forms a wellorganized molecular layer on the gold substrates. The orientation of the aromatic ring relative to the gold surface was investigated by means of the angle defined as the normal to the aromatic ring relative to the normal to the gold surface. It was shown that the average tilt angle is approximately 62º. In a second step, the  benzenesulfonamideterminated thiol monolayer was exposed to carbonic anhydrase, which is an enzyme and a therapeutic target. Benzenesulfonamides are used in biomedical applications as inhibitors for carbonic anhydrase. Our purpose in this study was to investigate the recognition capability of the benzenesulfonamide when designed as a thiol monolayer. The interaction between the benzenesulfonamide-terminated monolayer and carbonic anhydrase was studied using ellipsometry and surface plasmon resonance. The results show that the benzenesulfonamide-terminated thiol adsorbed onto the gold substrates is able to bind carbonic anhydrase. The results also indicate that the interaction is specific.

  • 223.
    Vahlberg, Cecilia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Yazdi, G. R.
    Khranovsky, V.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Surface engineering of functional materials for biosensors2005In: IEEE Sensors 2005,2005, 2005, p. 504-Conference paper (Refereed)
  • 224.
    Vahlberg, Cecilia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Yazdi, Gholam Reza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Khranovskyy, V.
    Petoral, Rodrigo Jr
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Surface engineering of functional materials for biosensors2006In: IEEE SENSORS 2005,2005, Proceedings IEEE SENSORS: ieee.org , 2006, p. 504-Conference paper (Refereed)
  • 225.
    Valiokas, R.
    et al.
    Department of Functional Nanomaterials, Institute of Physics, Savanoriu.
    Kienkar, G.
    Tinazli, A.
    Institute of Biochemistry, Johann Wolfgang Goethe-University, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany.
    Reichel, A.
    Tampe, R.
    Piehler, J.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Self-assembled monolayers containing terminal mono-, bis-, and tris-nitrilotriacetic acid groups: Characterization and application2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 9, p. 4959-4967Article in journal (Refereed)
    Abstract [en]

    We have undertaken a structural and functional study of self-assembled monolayers (SAMs) formed on gold from a series of alkylthiol compounds containing terminal multivalent chelators (MCHs) composed of mono-, bis-, and tris-nitrilotriacetic acid (NTA) moieties. SAMs were formed from single-component solutions of the mono-, bis-, and tris-NTA compounds, as well as from mixtures with a tri(ethylene glycol)-terminated alkylthiol (EG3). Contact angle goniometry, null ellipsometry, and infrared spectroscopy were used to explore the structural characteristics of the MCH SAMs. Ellipsometric measurements show that the amount of the MCH groups on surfaces increases with increasing mol % of the MCH thiols in the loading solution up to about 80 mol %. We also conclude that mixed SAMs, prepared in the solution composition regime 0-30 mol % of the MCH thiols, consist of a densely packed alkyl layer, an amorphous ethylene glycol layer, and an outermost layer of MCH groups exposed toward the ambient. Above 30 mol %, a significant degree of disorder is observed in the SAMs. Finally, functional evaluation of the three MCH SAMs prepared at 0-30 mol% reveals a consistent increase in binding strengdi with increasing multivalency. The tris-NTA SAM, in particular, is enabled for stable and functional immobilization of a His6-tagged extracellular receptor subunit, even at low chelator surface concentrations, which makes it suitable for applications when a low surface density of capturing sites is desirable, e.g., in kinetic analyses. © 2008 American Chemical Society.

  • 226.
    Valiokas, Ramunas
    et al.
    Molecular Compounds Physics Laboratory, Institute of Physics, Vilnius, Lithuania.
    Klenkar, Goran
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Tinazli, Ali
    Goethe University Frankfurt/Main, Institute of Biochemistry, Frankfurt/Main, Germany.
    Tampé, Robert
    Goethe University Frankfurt/Main, Institute of Biochemistry, Frankfurt/Main, Germany.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Piehler, Jacob
    Goethe University Frankfurt/Main, Institute of Biochemistry, Frankfurt/Main, Germany.
    Differential Protein Assembly on Micropatterned Surfaces with Tailored Molecular and Surface Multivalency2006In: ChemBioChem, ISSN 1439-4227, Vol. 7, no 9, p. 1325-1329Article in journal (Refereed)
  • 227.
    Valiokas, Ramunas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Malysheva, L.
    Bogolyubov Institute for Theoretical Physics.
    Onipko, A.
    Bogolyubov Institute for Theoretical Physics.
    Lee, Hung-Hsun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Ruzele, Z.
    Institute of Physics, Lithuania.
    Svedhem, S.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Svensson, S.C.T.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Gelius, U.
    Uppsala University.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    On the quality and structural characteristics of oligo(ethylene glycol) assemblies on gold: An experimental and theoretical study2009In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 172, no 1-3, p. 9-20Article in journal (Refereed)
    Abstract [en]

    This paper presents results of several years of experimental and theoretical work on a library of oligo(ethylene glycol)-containing self-assembled monolayers (OEG SAMs) on gold. The library consists of 15 different thiol compounds, which all contain alkyl and OEG portions of different length, as well as amide moieties forming a stabilizing lateral hydrogen bonding network. We have investigated the quality, conformation, orientation, defect structure and infrared (IR) signatures of these OEG SAMs prepared by spontaneous adsorption from dilute solutions. It is shown that solution concentration and incubation time are important factors to obtain high quality SAMs, in particular for those containing long OEG chains. Further on, the thiol compounds should contain a sufficiently long alkyl spacer to provide in plane van der Waals interactions strong enough to govern the formation of a densely packed alkylthiolate overlayer on the Au(1 1 1) surface. Such a highly ordered alkyl support, which is additionally stabilized by the lateral hydrogen bonds, enables us to vary the length of the terminal OEG portion from 1 to at least 12, without affecting the integrity and conformational characteristics of the supporting (alkyl) part of the SAM. Also, we discuss the importance of appropriate modeling tools to advance the understanding of IR signatures of the OEG SAMs. Finally, we demonstrate the generality of our "modular approach" by analyzing the structure of OEG SAMs formed by compounds extended with an additional terminal amide and an alkyl tail. Thus, the SAMs discussed herein provide an attractive platform for construction of advanced nanoarchitectures on surfaces, not only limited to biomaterials and fouling applications.

  • 228.
    Valiokas, Ramunas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Svedhem, Sofia
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. University of Uppsala, Department of Physics, Uppsala, Sweden.
    Östblom, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Gelius, U
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. University of Uppsala, Department of Physsics, Uppsala, Sweden.
    Svensson, SCT
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Tunable phases of oligo (ethylene glycol) in self-assembled monolayers and their use as support for lipid bilayers2000In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 219, p. 397-397Article in journal (Other academic)
  • 229.
    Valiokas, Ramunas
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Svedhem, Sofia
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Östblom, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Svensson, Stefan
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Influence of specific intermolecular interactions on the self-assembly and phase behavior of oligo(ethylene glycol)-terminated alkanethiolates on gold2001In: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 105, no 23, p. 5459-5469Article in journal (Refereed)
    Abstract [en]

    A comparative study of the self-assembly and phase behavior of seven different oligo(ethylene glycol) (OEG)-terminated alkanethiols on polycrystalline gold surfaces is presented. The general structure of the compounds is HS(CH2)m-X-EGn, where m = 11, 15, n = 2, 4, 6, and the linkages X are amide (-CONH-), ester (-COO-), or ether (-O-) groups. The amide and ester groups give rise to the intermolecular hydrogen bonding and dipole-dipole interactions, respectively, whereas the ether lacks specific interactions. The results from contact angle goniometry, null ellipsometry, and infrared reflection-absorption spectroscopy (IRAS) indicate that the intermolecular interactions can be partly used to control the conformation and order of the OEG portion of the self-assembled monolayers (SAMs). It is shown that the lateral hydrogen bonding stabilizes the all-trans conformation of the EG4 tails in the SAMs. Further on, the mechanism behind the thermal phase behavior of the OEG SAMs is investigated using temperature-programmed IRAS in ultrahigh vacuum. In the present study we show that the earlier reported helix-to-all-trans conformational transition at 60°C in the SAM of HS(CH2)15CONH-EG6 (Valiokas, R., Östblom, M., Svedhem, S., Svensson, S. C. T., Liedberg, B. J. Phys. Chem. 2000, 104, 7565-7569.) is a result of the particular molecular design of the SAMs through the specifically built-in lateral hydrogen bonds. A shortening of the alkyl chain to 11 methylenes has no effect on the amide-EG6 phase behavior. Contrary, the ester- and ether- containing SAMs undergo a melting type of transitions at 52 and 68°C, respectively, similar to that observed for poly(ethylene glycol).

  • 230.
    Valiokas, Ramunas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Vaitekonis, Sarunas
    Inst of Physics Molecular Compounds Physics Laboratory, Savanoriu 231, Vilnius, Lithuania.
    Klenkar, Goran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Trinkunas, Gediminas
    Inst of Physics Molecular Compounds Physics Laboratory, Savanoriu 231, Vilnius, Lithuania.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Selective Recruitment of Membrane Protein Complexes onto Gold Substrates Patterned by Dip-Pen Nanolithography2006In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, p. 3456-3460Article in journal (Refereed)
  • 231.
    Valiokas, Ramunas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Östblom, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Björefors, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Shi, Jing
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry.
    Structural and kinetic properties of laterally stabilized, oligo(ethylene glycol)-containing alkylthiolates on gold: A modular approach2006In: Biointerphases, ISSN 1934-8630, E-ISSN 1559-4106, Vol. 1, no 1, p. 22-34Article in journal (Refereed)
    Abstract [en]

    The formation of highly ordered self-assembled monolayers (SAMs) on goldfrom an unusually long and linear compound HS(CH2)15CONH(CH2CH2O)6CH2CONH(CH2)15CH3 is investigated by contact angle goniometry, ex situ null ellipsometry, cyclic voltammetry and infrared reflection-absorption spectroscopy. The molecules are found to assemble in an upright position as a complete monolayer within 60 min. The overall structure of the SAM reaches equilibrium within 24 h as evidenced by infrared spectroscopy, although a slight improvement in water contact angles is observed over a period of a few weeks. The resulting SAM is 60 Å thick and it displays an advancing water contact angle of 112° and excellent electrochemicalblocking characteristics with typical current densities about 20 times lower as compared to those observed for HS(CH2)15CH3 SAMs. The dominating crystalline phases of the supporting HS(CH2)15 and terminal (CH2)15CH3 alkyl portions, as well as the sealed oligo(ethylene glycol) (OEG) “core,” appear as unusually sharp features in the infrared spectra at room temperature. For example, the splitting seen for the CH3 stretching and CH2 scissoring peaks is normally only observed for conformationally trapped alkylthiolate SAMs at low temperatures and for highly crystalline polymethylenes. Temperature-programmed infrared spectroscopy in ultrahigh vacuum reveals a significantly improved thermal stability of the SAM under investigation, as compared to two analogous OEG derivatives without the extended alkyl chain. Our study points out the advantages of adopting a “modular approach” in designing novel SAM-forming compounds with precisely positioned in plane stabilizing groups. We demonstrate also the potential of using the above set of compounds in the fabrication of “hydrogel-like” arrays with controlled wetting properties for application in the ever-growing fields of protein and cell analysis, as well as for bioanalytical applications.

  • 232.
    Valiokas, Ramunas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Östblom, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Svedhem, Sofia
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Svensson, Stefan C. T.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Temperature-driven phase transitions in oligo(ethylene glycol)-terminated self-assembled monolayers2000In: The Journal of Physical Chemistry B, ISSN 1520-6106, Vol. 104, no 32, p. 7565-7569Article in journal (Other academic)
    Abstract [en]

    This letter explores the phase behavior of oligo(ethylene glycol) self-assembled monolayers using temperature-programmed infrared reflection absorption spectroscopy. The monolayers are formed by self-assembly of hexa(ethylene glycol) (EG(6)) and tetra(ethylene glycol) (EG(4))-terminated and amide group containing alkanethiols on polycrystalline gold. The ethylene glycol portions of the two monolayers are known to exist in two different conformations at room temperature: EG(6) in helical and EG(4) in all-trans (zigzag). The helical phase of the EG(6) gradually diminishes upon increasing the temperature and a pronounced conformational transition occurs around 60 degrees C, leading to a rapidly increasing population of all-trans conformers along the EG(6) chain. The EG(4) SAM exhibits a much simpler phase behavior. The oligomer conformation is marginally affected upon increasing the temperature to 75 degrees C, displaying the dominating all-trans phase, which possibly coexists with a small fraction of gauche-rich (disordered) regions. The reported conformational changes are reversible upon returning to 20 degrees C after stepwise heating to 70 degrees C.

  • 233.
    Valiokas, Ramunas
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Östblom, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Svedhem, Sofia
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Svensson, Stefan C.T.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Thermal stability of self-assembled monolayers: Influence of lateral hydrogen bonding2002In: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 106, no 40, p. 10401-10409Article in journal (Refereed)
    Abstract [en]

    Temperature-programmed desorption (TPD) of self-assembled monolayers (SAMs) on gold is investigated by using in parallel mass spectrometry (MS) and infrared reflection-absorption spectroscopy (IRAS). Monolayers formed by HS(CH2)n-OH (n = 18, 22) and HS(CH2)15-CONH-(CH2CH2O)-H (EG1) are compared to reveal the influence of specifically introduced hydrogen-bonding groups on their thermal stability. The overall desorption process of the above molecules is found to occur in two main steps, a disordering of the alkyl chains followed by a complex series of decomposition/desorption reactions. The final step of the process involves desorption of sulfur from different chemisorption states. The amide-group-containing SAM, which is stabilized by lateral hydrogen bonds, displays a substantial delay of the alkyl chain disordering by about 50 K, as compared to the linear chain alcohols HS(CH2)n-OH. Moreover, the decomposition of the alkyls and the onset of sulfur desorption occur at a temperature that is higher by approximately 25 K as compared to the HS(CH2)18-OH SAM. The desorption process is also studied for two oligo(ethylene glycol)-terminated SAMs, HS(CH2)15-X-(CH2CH2O)4-H (EG4-SAMs), where X is -CONH- and -COO- linking groups. In addition to the molecular chain disordering, the decomposition/desorption process of the EG4-SAMs occurs in two steps. The first is associated with the loss of the oligomer portion and the second with the desorption of the alkylthiolate part of the molecule. Our study points out that lateral hydrogen bonding, introduced via amide groups, is a convenient way to improve the thermal stability of alkanthiolate SAMs.

  • 234.
    Viljanen, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Larsson, Jenny
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Larsson (Kaiser), Andréas
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Broo, Kerstin S.
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    A Multipurpose Receptor Composed of Promiscuous Proteins. Analyte Detection through Pattern Recognition2007In: Bioconjugate Chemistry, ISSN 1043-1802, Vol. 18, no 6, p. 1935-1945Article in journal (Refereed)
    Abstract [en]

    A multipurpose receptor akin to the “electronic nose” was composed of coumarin-labeled mutants of human glutathione transferase A1. We have previously constructed a kit for site-specific modification of a lysine residue (A216K) using a thiol ester of glutathione (GSC-Coubio) as a modifying reagent. In the present investigation, we scrambled the hydrophobic binding site (H-site) of the protein scaffold through mutations at position M208 via random mutagenesis and isolated a representative library of 11 A216K/M208X mutants. All of the double mutants could be site-specifically labeled to form the K216Cou conjugates. The labeled proteins responded to the addition of different analytes with signature changes in their fluorescence spectra resulting in a matrix of 96 data points per analyte. Ligands as diverse as n-valeric acid, fumaric acid monoethyl ester, lithocholic acid, 1-chloro-2,4-dinitrobenzene (CDNB), glutathione (GSH), S-methyl-GSH, S-hexyl-GSH, and GS-DNB all gave rise to signals that potentially can be interpreted through pattern recognition. The measured Kd values range from low micromolar to low millimolar. The cysteine residue C112 was used to anchor the coumarin-labeled protein to a PEG-based hydrogel chip in order to develop surface-based biosensing systems. We have thus initiated the development of a multipurpose, artificial receptor composed of an array of promiscuous proteins where detection of the analyte occurs through pattern recognition of fluorescence signals. In this system, many relatively poor binders each contribute to detailed readout in a truly egalitarian fashion.

  • 235.
    Wang, Xiangjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    In-situ Wilhelmy balance surface energy determination of poly(3-hexylthiophene) and poly(3,4-ethylenedioxythiophene) during electrochemical doping-dedoping2006In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, no 22, p. 9287-9294Article in journal (Refereed)
    Abstract [en]

    Changes in the contact angle between conjugated polymers surface poly(3-hexylthiophene) [P3HT] and poly(3,4-ethylenedioxythiophene) (PEDOT) upon electrochemical doping−dedoping in aqueous electrolyte were determined in situ using a Wilhelmy plate tensiometer in an electrochemical cell. The hydrophobic P3HT was less hydrophobic in the oxidized state than in the neutral state; the more hydrophilic PEDOT was less hydrophilic in the oxidized state than when neutral. The tensiometry results were in good agreement with those measured by contact angle goniometry, and further corroborated by the capillary rise upon doping in a fluid cell with two parallel polymer coated plates, another in situ dynamic determination method. The contact angle changes depend on doping potential, electrolyte type, and concentration. We also deconvoluted the surface energy into components of van der Waals and acid−base interactions, using three probe liquids on the polymer surfaces, ex situ the electrochemical cell. The methods and the obtained results are relevant for the science and technology areas of printed electronics and electrochemical devices and for the understanding of surface energy modification by electrochemical doping.

  • 236.
    Wang, Xiangjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Östblom, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Johansson, Tomas
    Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    PEDOT surface energy pattern controls fluorescent polymer deposition by dewetting2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 449, no 1-2, p. 125-132Article in journal (Refereed)
    Abstract [en]

    An elastomeric stamp of poly(dimethylsiloxane) (PDMS) can modify the surface energy of some surfaces when brought into conformal contact with these for some time. The substrates under investigation are a conducting polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) and a polyelectrolyte poly(sodium 4-styrenesulfonate) (NaPSS). The changes in surface wetting are characterized by contact angle measurement. Changes are due to the PDMS stamp, which leaves low molecular weight residues on the surface, as shown by infrared reflection absorption spectroscopy. This process may also be operating when other inks are transferred in microcontact printing. Patterning of fluorescent polymer film with feature size of 10–100 μm range is done by confining polymer solutions on the modified surface, by means of spin- or dip-coating. The profile of the patterned film and factors that influence the profile are discussed. This technique is a convenient way to build polymer microstructures for application in organic and biomolecular electronics and photonics.

  • 237.
    Wang, Yusong
    et al.
    Nanyang Technology University, Singapore Nanyang Technology University, Singapore .
    Aili, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Selegård, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Tay, Yeeyan
    Nanyang Technology University, Singapore .
    Baltzer, Lars
    Uppsala University, Sweden .
    Zhang, Hua
    Nanyang Technology University, Singapore Nanyang Technology University, Singapore .
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Specific functionalization of CTAB stabilized anisotropic gold nanoparticles with polypeptides for folding-mediated self-assembly2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 38, p. 20368-20373Article in journal (Refereed)
    Abstract [en]

    Anisotropic nanoparticles stabilized by cetyltrimethylammonium bromide (CTAB) are notoriously difficult to homogenously functionalize using conventional gold-thiol chemistry. Using surface assisted laser desorption time of flight mass spectroscopy and scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, we demonstrate that silver species adsorbed on the particle surface prevent effective surface functionalization. When covered by a thin gold film, particle functionalization was drastically improved. A thiol-containing polypeptide was immobilized on arrowhead gold nanorods (NRs) and was subsequently able to selectively heteroassociate with a complementary polypeptide resulting in a folding-mediated bridging aggregation of the NRs. Despite using arrowhead NRs with a pronounced difference in surface arrangement on the {111} facets on the arrowheads compared to the {100} facets at the particle sides, the polypeptides were efficiently and homogeneously immobilized on the particles after gold film overgrowth.

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  • 238.
    Wetterö, Jonas
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rheumatology.
    Hellerstedt, T.
    Nygren, Patrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Broo, K.
    Occupational and Environmental Medicine, Sahlgrenska University Hospital, Göteborg University, Göteborg, Sweden.
    Aili, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics.
    Magnusson, Karl-Eric
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology.
    Immobilized chemoattractant peptides mediate adhesion and distinct calcium-dependent cell signaling in human neutrophils2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 13, p. 6803-6811Article in journal (Refereed)
    Abstract [en]

    Chemotaxis is the stimulated directional migration of cells in response to chemotactic factors, manifested for instance during leukocyte interaction with chemoattractants in inflammation. The N-formyl-Met-Leu-Phe (fMLF) bacterial peptide family is particularly potent in attracting and activating neutrophilic granulocytes. To accomplish defined circumstances for recruitment and activation of cells, we fabricated semitransparent gold-coated glass coverslips functionalized with chemoattractant fMLF receptor peptide agonist analogues. Peptides based on a common leading four-amino-acid sequence Gly-Gly-Gly-Cys were thus coupled to two potent fMLF receptor agonists, N-formyl-Tyr-Nle-Phe-Leu- Nle-Gly-Gly-Gly-Cys and N-formyl-Met-Leu-Phe-Gly-Gly-Gly-Cys, and a formylated control peptide, N-formyl-Gly-Gly-Gly-Cys. They were anchored via the SH group of Cys either directly to the gold surface or a mixed self-assembled monolayer composed of maleimide- and hydroxyl-terminated oligo(ethylene glycol) alkyldisulfides. The overall peptide immobilization procedure was characterized with ellipsometry, contact angle measurement, and infrared spectroscopy. When exposed to granulocytes, the agonist surface rapidly recruited neutrophils and the cells responded with extensive spreading and intracellular calcium transients within minutes. The reference peptide generated no such activation, and the cells maintained a more spherical morphology, suggesting that we have been able to immobilize chemoattractant receptor agonist peptides with retained bioactivity. This is a crucial step in designing surfaces with specific effects on cellular behavior. © 2008 American Chemical Society.

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  • 239.
    Wibisono, Yusuf
    et al.
    University of Twente, Netherlands; Wetsus, Netherlands.
    Yandi, Wetra
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Golabi, Mohsen
    Nugraha, Roni
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Cornelissen, Emile R.
    KWR Watercycle Research Institute, Netherlands.
    Kemperman, Antoine J. B.
    University of Twente, Netherlands.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Nijmeijer, Kitty
    University of Twente, Netherlands.
    Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation2015In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 71, p. 171-186Article in journal (Refereed)
    Abstract [en]

    Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG(10)MA), cationic (polyDMAEMA) and anionic (polySPMA) hydrogels have been successfully grafted onto polypropylene (PP) feed spacers via plasma-mediated UV-polymerization. These coatings maintained their chemical stability after 7 days incubation in neutral (pH 7), acidic (pH 5) and basic (pH 9) environments. Anti-biofouling properties of these coatings were evaluated by Escherichia coli attachment assay and nanofiltration experiments at a TMP of 600 kPag using tap water with additional nutrients as feed and by using optical coherence tomography. Especially the anionic polySPMA-coated PP feed spacer shows reduced attachment of E. coli and biofouling in the spacer-filled narrow channels resulting in delayed biofilm growth. Employing this highly hydrophilic coating during removal of biofouling by two-phase flow cleaning also showed enhanced cleaning efficiency, feed channel pressure drop and flux recoveries. The strong hydrophilic nature and the presence of negative charge on polySPMA are most probably responsible for the improved antifouling behavior. A combination of polySPMA-coated PP feed spacers and two-phase flow cleaning therefore is promising and an environmentally friendly approach to control biofouling in NF/RO systems employing spiral-wound membrane modules.

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  • 240.
    Wigenius, Jens
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Magnusson, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Björk, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Andersson, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    DNA Chips with Conjugated Polyelectrolytes in Resonance Energy Transfer Mode2010In: LANGMUIR, ISSN 0743-7463, Vol. 26, no 5, p. 3753-3759Article in journal (Refereed)
    Abstract [en]

    We show how to use well-defined conjugated polyelectrolytes (CPEs) combined With Surface energy patterning to Fabricate DNA Chips utilizing A fluorescence signal amplification. Cholesterol-modified DNA strands in complex with it CPE are adsorbed to a surface energy pattern, formed by printing with soft elastomer stamps. Hybridization of the surface bound DNA strands with it short complementary strand from Solution is monitored using both fluorescence microscopy and imaging surface plasmon resonance. The CPEs act as antennas, enhancing resonance energy transfer to the dye-labeled DNA when complementary hybridization of the double strand occurs.

  • 241.
    Yakimova, Rositza
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Selegård, Linnea
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, The Institute of Technology.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pearce, Ruth
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    ZnO materials and surface tailoring for biosensing2012In: Frontiers in bioscience (Elite edition), ISSN 1945-0508, Vol. 4, no 1, p. 254-278Article in journal (Refereed)
    Abstract [en]

    ZnO nanostructured materials, such as films and nanoparticles, could provide a suitable platform for development of high performance biosensors due to their unique fundamental material properties. This paper reviews different preparation techniques of ZnO nanocrystals and material issues like wettability, biocompatibility and toxicity, which have an important relevance to biosensor functionality. Efforts are made to summarize and analyze existing results regarding surface modification and molecular attachments for successful biofunctionalization and understanding of the mechanisms involved. A section is devoted to implementations of tailored surfaces in biosensors. We end with conclusions on the feasibility of using ZnO nanocrystals for biosensing.

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  • 242.
    Yang, Yi
    et al.
    Chinese Academy of Science.
    Zhang, Jing
    Chinese Academy of Science.
    Zhou, Ye
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Zhao, Guangjin
    Chinese Academy of Science.
    He, Chang
    Chinese Academy of Science.
    Li, Yongfang
    Chinese Academy of Science.
    Andersson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Solution-Processable Organic Molecule with Triphenylamine Core and Two Benzothiadiazole-Thiophene Arms for Photovoltaic Application2010In: JOURNAL OF PHYSICAL CHEMISTRY C, ISSN 1932-7447, Vol. 114, no 8, p. 3701-3706Article in journal (Refereed)
    Abstract [en]

    A new solution-processable biarmed organic molecule With triphenylamine (TPA) core and benzothiadiazole-hexylthiophene (BT-HT) arms, B(TPA-BT-HT), has been synthesized by a Heck reaction, and characterized by UV-vis absorption, cyclic voltammetry, and theoretical calculation. Photovoltaic properties of B(TPA-BT-HT) as light-harvesting and electron-donating material in organic solar cells (OSCs), with [6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) as acceptors, were systematically investigated. The performance of the OSCs varied significantly with B(TPA-BT-HT)/fullerene weight ratio, active layer thickness, and solvents Used For spin-coating the active layer. The optimized device with the B(TPA-BT-HT)/PC70BM weight ratio of 1:2 and a thickness of 55 nm with the active layer spin-coated from DCB solution Shows a power conversion efficiency of 1.96% with a short-circuit current density of 5.50 mA/cm(2) and in open-circuit voltage of 0.96 V under (lie illumination of AM 1.5, 100 mw/cm(2).

  • 243.
    Zhou, Ye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Andersson, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Lindberg, Peter
    Biacore AB, Rapsgatan 7, S-754 50, Uppsala, Sweden.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Protein Microarrays on Carboxymethylated Dextran Hydrogels: Immobilization, Characterization and Application2004In: Microchimica Acta, ISSN 0026-3672, E-ISSN 1436-5073, Vol. 147, no 1-2, p. 21-30Article in journal (Refereed)
    Abstract [en]

    Tetraoctadecylammonium bromide (TOAB, (CH3(CH2)17)4N+Br) has been used to print temporary hydrophobic barriers on carboxymethylated dextran (CMD) hydrogels to create a generic platform for protein microarray applications. The primary reason for printing temporary hydrophobic barriers is to prevent cross-contamination and overflow during microdrop dispensing. Equally important is to eliminate the risk for non-specific binding to the barriers during analyte exposure. This has been accomplished by introducing a regeneration step that removes the barriers after ligand immobilization. The overall fabrication process was characterized by microscopic wetting, atomic force microscopy, imaging ellipsometry, fluorescence microscopy, surface plasmon microscopy and biospecific interaction analysis. A series of model proteins including transferrin, Protein A, anti-myoglobin and bovine serum albumin was spotted into the TOAB-defined areas under different experimental conditions, e.g. at increased humidity and reduced substrate temperature or with glycerol as an additive in the protein solution. Much emphasis was devoted to studies aiming at exploring the homogeneity and activity of the immobilized proteins. The printed barriers were removed after protein immobilization using tert-n-butyl alcohol (TBA). TBA was found to be a very efficient agent as compared to previously used salt regeneration solutions, and the regeneration time could be reduced from 30 to 10 minutes. Finally, the potential of using the well established CMD hydrogel chemistry as a platform for protein microarrays was exploited using surface plasmon microscopy.

  • 244.
    Zhou, Ye
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Andersson, Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lindberg, P.
    Biacore AB, Rapsgatan 7, S-754 50 Uppsala, Sweden.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Reversible hydrophobic barriers introduced by microcontact printing: Application to protein microarrays2004In: Mikrochimica Acta, ISSN 0026-3672, E-ISSN 1436-5073, Vol. 146, no 3-4, p. 193-205Article in journal (Refereed)
    Abstract [en]

    Microcontact printing (µCP) has been used to introduce temporary hydrophobic barriers on carboxymethylated dextran (CMD) hydrogels on gold. Among the investigated types of inks, tetraoctadecylammonium bromide (TOAB), electrostatically bound to the CMD layer, provided the most well-defined features both with respect to pattern-definition and reversibility upon exposure to a regeneration solution. The printed patterns were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), microscopic wetting and imaging null ellipsometry to explore the influence of concentration of ink solution and contact time on the appearance of the printed layer. AFM revealed that the printed TOAB molecules aggregated into clusters rather than into a homogeneous mono- or multilayer on the CMD hydrogel. It was also observed that printed areas of TOAB that are larger than 25?µm are inhomogeneous most likely because of an edge transfer lithography (ETL) mechanism. A protein model system based on Protein A-rabbit antimouse Fc ? was used to evaluate the potential of the patterned surface as a protein microarray chip by means of surface plasmon microscopy (SPM). Moreover, non-specific adsorption of several proteins onto TOAB barriers was also studied using surface plasmon resonance (SPR), and it is evident that undesired adsorption can be eliminated by removing barriers after ligand immobilization, but prior to analyte exposure, by treating the patterned surface with a simple salt regeneration solution. © Springer-Verlag/Wien 2004.

  • 245.
    Zhou, Ye
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Gorochovceva, Natalija
    Polymer chemistry Vilnius University.
    Makuska, Ricardas
    Polymer Chemistry Vilnius University.
    Dedinaite, Andra
    Surface Chemistry KTH.
    Claesson, Per M.
    Surface Chemistry KTH.
    Chitosan-N-poly(ethylene oxide) brush polymers for reduced nonspecific protein adsorption2007In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 305, no 1, p. 62-71Article in journal (Refereed)
    Abstract [en]

    The possibility of using a novel comb polymer consisting of a chitosan backbone with grafted 44 units long poly(ethylene oxide) side chains for reducing nonspecific protein adsorption to gold surfaces functionalized by COOH-terminated thiols has been explored. The comb polymer was attached to the surface in three different ways: by solution adsorption, covalent coupling, and microcontact printing. The protein repellant properties were tested by monitoring the adsorption of bovine serum albumin and fibrinogen employing surface plasmon resonance and imaging null ellipsometry. It was found that a significant reduction in protein adsorption is achieved as the comb polymer layer is sufficiently dense. For solution adsorption this was achieved by adsorption from high pH solutions. On the other hand, the best performance of the microcontact printed surfaces was obtained when the stamp was inked either at low or at high pH. For a given comb polymer layer thickness/poly(ethylene oxide) density, significant differences in protein repellant properties were observed between the different preparation methods, and it is suggested that a reduction in the mobility of the comb polymer layer generated by covalent attachment favors a reduced protein adsorption. © 2006 Elsevier Inc. All rights reserved.

  • 246.
    Zhou, Ye
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Valiokas, Ramunas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Structural characterization of microcontact printed arrays of hexa(ethylene glycol)-Terminated alkanethiols on gold2004In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, no 15, p. 6206-6215Article in journal (Refereed)
    Abstract [en]

    This paper reports on the structural characteristics of microcontact printed oligo(ethylene glycol)-terminated alkanethiol layers, HS(CH 2)15CONH-(CH2CH2O)6-H (hereafter EG6), on gold. Microwetting, contact angle goniometry, imaging null ellipsometry, and infrared reflection-absorption spectroscopy (IRAS) are used to characterize the printed EG6 layers, and the quality of these layers in terms of layer thickness and the crystallinity of the alkyl and ethylene glycol portions is compared with data obtained from analogous layers prepared by solution self-assembly. The outcome of the printing process is critically dependent on the experimental parameters used to prepare the patterns. It is found that high quality layers, consisting of densely packed all-trans alkyl chains terminated with relatively helical hexa( ethylene glycol) tails, are formed by inking the poly(dimethylsiloxane) (PDMS) stamp with a 1 mM EG6 solution and contacting it with gold for 15 min. The homogeneity of printed layers is not as good as the homogeneity of those prepared from solution under similar conditions, most likely because of simultaneous transfer of low molecular weight residues from the PDMS stamp. These residues, however, can be easily removed upon ultrasonication in ethanol without affecting the quality of the printed layer. Further on, the microscopic square-shaped bare gold patterns formed after microcontact printing (µCP) are subsequently filled with 16-hexadecanoic acid (hereafter THA) or HS(CH 2)15CONH-(CH2CH2O)6-COOH (hereafter EG6COOH) to provide a microarray platform for further covalent attachment of biomolecules. Well-defined structures in terms of wettability contrast, sharpness, and height differences between the printed and back-filled areas are confirmed by imaging null ellipsometry and microscopic wetting.

  • 247.
    Zhou, Ye
    et al.
    Lund Univ, Div Solid State Phys, SE-22100 Lund, Sweden.
    Xu, Hongxing
    Lund Univ, Div Solid State Phys, SE-22100 Lund, Sweden.
    Dahlin, Andreas B.
    Lund Univ, Div Solid State Phys, SE-22100 Lund, Sweden.
    Vallkil, Jacob
    Lund Univ, Dept Immunotechnol, SE-22007 Lund, Sweden.
    Borrebaeck, Carl A. K.
    Lund Univ, Dept Immunotechnol, SE-22007 Lund, Sweden.
    Wingren, Christer
    Lund Univ, Dept Immunotechnol, SE-22007 Lund, Sweden.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Hook, Fredrik
    Lund Univ, Div Solid State Phys, SE-22100 Lund, Sweden.
    Quantitative interpretation of gold nanoparticle-based bioassays designed for detection of immunocomplex formation2007In: BIOINTERPHASES, ISSN 1559-4106, Vol. 2, no 1Article in journal (Refereed)
    Abstract [en]

    The authors present in this paper how the extended Mie theory can be used to translate not only end-point data but also temporal variations of extinction peak-position changes, Delta lambda(peak)(t), into absolute mass uptake, Gamma(t), upon biomacromolecule binding to localized surface plasmon resonance (SPR) active nanoparticles (NPs). The theoretical analysis is applied on a novel sensor template composed of a three-layer surface architecture based on (i) a self-assembled monolayer of HS(CH2)(15)COOH, (ii) a 1:1 mixture of biotinylated and pure poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), and (iii) NeutrAvidin. Assisted by independent estimations of the thickness of the three-layer architecture using quartz crystal microbalance with dissipation (QCM-D) monitoring, excellent agreement with parallel mass-uptake estimations using planar SPR is obtained. Furthermore, unspecific binding of serum to PLL-g-PEG was shown to be below the detection limit, making the surface architecture ideally suited for label-free detection of immunoreactions. To ensure that the immunocomplex formation occurred within the limited sensing depth (similar to 10 nm) of the NPs, a compact model system composed of a biotinylated human recombinant single-chain antibody fragment (empty set similar to 2 nm) directed against cholera toxin was selected. By tracking changes in the centroid (center of mass) of the extinction peak, rather than the actual peak position, signal-to-noise levels and long-term stability upon cholera toxin detection are demonstrated to be competitive with results obtained using conventional SPR and state-of-the-art QCM-D data. (C) 2007 American Vacuum Society.

  • 248.
    Östblom, Mattias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Ekeroth, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Konradsson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Structure and desorption energetics of ultrathin D2O ice overlay ers on serine- And serinephosphate-terminated self-assembled monolayers2006In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, no 4, p. 1695-1700Article in journal (Refereed)
    Abstract [en]

    This paper reports on the structure and desorption dynamics of thin D 2O ice overlayers (0.2-10 monolayers) deposited on serine- and serinephosphate- (with H+, Na+, Ca2+ counterions) terminated self-assembled monolayers (SAMs). The D2O ice overlayers are deposited on the SAMs at ~85 K in ultrahigh vacuum and characterized with infrared reflection absorption spectroscopy (IRAS). Reflection absorption (RA) spectra obtained at sub-monolayer D2O coverage reveal that surface modes, e.g. free dangling OD stretch, dominate on the serine SAM surface, whereas vibrational modes characteristic for bulk ice are more prominent on the serinephosphate SAMs. Temperature programmed desorption mass spectrometry (TPD-MS) and TPD-IRAS are subsequently used to investigate the energetics and the structural transitions occurring in the ice overlayer during temperature ramping. D2O ice (~2.5 monolayers) on the serine SAMs undergoes a gradual change from an amorphous- to a crystalline-like phase upon increasing the substrate temperature. This transition is not as pronounced on the serine phosphate SAM most likely because of reduced mobility due to strong pinning to the surface. We show also that the energy of desorption for a sub-monolayer of D2O ice on serinephosphate SAM surfaces with a Na+ and Ca2+ counterions is equally high or even exceeds previously reported values for analogous high-energy SAMs. © 2006 American Chemical Society.

  • 249.
    Östblom, Mattias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Demers, L.M.
    Department of Chemistry, Center for Nanofabrication and Molecular Self-Assembly, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208.
    Mirkin, C.A.
    Department of Chemistry, Center for Nanofabrication and Molecular Self-Assembly, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208.
    On the structure and desorption dynamics of DNA bases adsorbed on gold: A temperature-programmed study2005In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 31, p. 15150-15160Article in journal (Refereed)
    Abstract [en]

    The structure and desorption dynamics of mono- and multilayer samples of adenine, cytosine, guanine, and thymine on polycrystalline gold thin films are studied using temperature-programmed desorption-infrared reflection absorption spectroscopy (TPD-IRAS) and temperature-programmed desorption-mass spectroscopy (TPD-MS). It is shown that the pyrimidines, adenine and guanine, adsorb to gold in a complex manner and that both adhesive (adenine) and cohesive (guanine) interactions contribute the apparent binding energies to the substrate surface. Adenine displays at least two adsorption sites, including a high-energy site (210°C, ~136 kj/mol), wherein the molecule coordinates to the gold substrate via the NH2 group in an sp3-like, strongly perturbed, nonplanar configuration. The purines, cytosine and thymine, display a less complicated adsorption/desorption behavior. The desorption energy for cytosine (160°C, ~122 kJ/mol) is similar to those obtained for adenine and guanine, but desorption occurs from a single site of dispersed, nonaggregated cytosine. Thymine desorbs also from a single site but at a significantly lower energy (100°C, ~104 kJ/mol). Infrared data reveal that the monolayer architectures discussed herein are structurally very different from those observed for the bases in the bulk crystalline state. It is also evident that both pyrimidines and purines adsorb on gold with the plane of the molecule in a nonparallel orientation with respect to the substrate surface. The results of this work are discussed in the context of improving the understanding of the design of capturing oligonucleotides or DNA strands for bioanalytical applications, in particular, for gold nanoparticle-based assays. © 2005 American Chemical Society.

  • 250.
    Östblom, Mattias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Valiokas, Ramunas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Konradsson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry .
    Svensson, Stefan
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Garrett, M.
    Department of Chemistry and Materials Science, Pennsylvania State University, University Park, PA 16802.
    Allara, D.L.
    Department of Chemistry and Materials Science, Pennsylvania State University, University Park, PA 16802.
    Ice nucleation and phase behavior on oligo(ethylene glycol) and hydroxyl self-assembled monolayers: Simulations and experiments2006In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, no 4, p. 1830-1836Article in journal (Refereed)
    Abstract [en]

    The nucleation and phase behavior of ultrathin D2O-ice overlayers have been studied on oligo(ethylene glycol) (OEG)-terminated and hydroxyl self-assembled monolayers (SAMs) at low temperatures in ultrahigh vacuum. Infrared reflection-absorption spectroscopy (IRAS) is used to characterize the ice overlayers, the SAMs, and the interactions occurring between the ice and the SAM surfaces. Spectral simulations, based on optical models in conjunction with Maxwell Garnett effective medium theory, point out the importance of including voids in the modeling of the ice structures, with void fractions reaching 60% in some overlayers. The kinetics of the phase transition from amorphous-like to crystalline-like ice upon isothermal annealing at 140 K is found to depend on the conformational state of the supporting OEG SAM surface. The rate is fast on the helical OEG SAMs and slow on the corresponding all-trans SAMs. This difference in kinetics is most likely due to a pronounced D2O interpenetration and binding to the all-trans segments of the ethylene glycol portion of the SAM. No such penetration and binding was observed on the helical OEG SAM. © 2006 American Chemical Society.

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