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  • 1.
    Bergkvist, Magnus
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Carlsson, J
    Uppsala University, Sweden.
    Karlsson, T
    Pharmacia and Upjohn Diagnostics, Sweden.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    TM-AFM Threshold Analysis of Macromolecular Orientation: A Study of the Orientation of IgG and IgE on Mica Surfaces.1998In: Journal of Colloid and Interface Science, ISSN 0021-9797, Vol. 206, no 2, p. 475-481Article in journal (Refereed)
    Abstract [en]

    Adsorption and orientation properties of two different types of immunoglobulin molecules on derivatized and native mica surfaces were investigated using TM-AFM. The analyses included height measurements at two different pH values and a new technique, presented here as threshold analysis, which displays the outer mantle shape of an adsorbed protein. A major difference in preferential orientation is observed upon comparing the adsorption of the two proteins onto the different surfaces. The characteristics of both the adsorbed immunoglobulin and the surface are important for any preferential orientation of the adsorbed protein.

  • 2.
    Bergkvist, Magnus
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering. Uppsala University, Sweden.
    Carlsson, Jan
    Uppsala University, Sweden.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering. Uppsala University, Sweden.
    Surface-dependent conformations of human plasma fibronectin adsorbed to silica, mica, and hydrophobic surfaces, studied with use of Atomic Force Microscopy2003In: Journal of biomedical materials research. Part A., ISSN 0021-9304, Vol. 64, no 2, p. 349-356Article in journal (Refereed)
    Abstract [en]

    Human plasma fibronectin (Fn) is a large flexible protein stabilized by intermolecular ionic interactions forming a compact structure. On altering solution conditions, the structure can revert to a more expanded state, thereby exposing previously hidden domains (e.g., cell-binding sites). Electron microscopy images of Fn air-sprayed onto mica surfaces show elongated protein structures, indicating a surface-induced structural change. This makes it interesting to investigate the influence of surface properties on the structure of adsorbed Fn. We have used intermittent-contact Atomic Force Microscopy to investigate the structure of Fn adsorbed onto mica, silica, and methylated silica surfaces. We observed that on silica surfaces, which is hydrophilic, most (70%) of the molecules had an elongated structure with partial intramolecular chain interactions, compare to molecules adsorbed on hydrophobic, methylated surfaces, where a compact structure predominated (70%). On mica surfaces, both compact and elongated protein structures were observed, with a slight preference for the elongated form (53%). Results show that surface physical properties influence the molecular structure of fibronectin on adsorption, which could provide useful information in understanding surface-induced in vivo responses.

  • 3.
    Berna, Nathalie
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Berna, P
    Uppsala University, Sweden.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Cosolvent-induced adsorption and desorption of serum proteins on an amphiphilic mercaptomethylene pyridine-derivatized agarose gel1996In: Arch Biochem Biophys, ISSN 0003-9861, Vol. 330, no 1, p. 188-192Article in journal (Refereed)
    Abstract [en]

    We studied the effects of the following cosolvents on the adsorption and desorption of serum proteins from an amphiphilic mercaptomethylene pyridine-derivatized agarose gel: glucose, sucrose, polyethylene glycol (PEG), 2-methyl-2,4-pentanediol (MFD), sorbitol, pentaerythritol, glycerol, and Na2SO4. The water-structuring salt 0.4 M Na2SO4 was the most potent promoter of protein adsorption, followed by 5 M sorbitol and, to a lesser extent, 0.2 M PEG 1000 and 2.25 M MPD. The other cosolvents (4 M glucose, 1.5 M sucrose, 0.3 M pentaerythritol, and 7.6 M glycerol) were unable to promote protein adsorption to the gel. Attempts to modulate the salt-promotion effect of Na2SO4 with different cosolvents demonstrated the occurrence of synergistic effects for pentaerythritol, sorbitol, and glucose and antagonistic effects for the other cosolvents. Sorbitol and glycerol were found to be the most interesting co-solvents studied, as the first promoted protein adsorption, whereas the other disrupted protein interaction. As a consequence of these novel findings we propose sorbitol and glycerol, both well-known protein stabilizers, as possible alternatives to water-structuring salts during the adsorption phase and to deleterious organic solvents during the desorption phase on amphiphilic gels.

  • 4.
    Berner, S.
    et al.
    Uppsala University, Sweden.
    Biela, S.
    Uppsala University, Sweden.
    Ledung, G.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Gogoll, A.
    Uppsala University, Sweden.
    Bäckvall, J.E.
    Stockholm University, Sweden.
    Puglia, C.
    Uppsala University, Sweden.
    Oscarsson, S.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Activity boost of a biomimetic oxidation catalyst by immobilization onto a gold surface2006In: Journal of Catalysis, ISSN 0021-9517, Vol. 244, no 1, p. 86-91Article in journal (Refereed)
    Abstract [en]

    Thiol-functionalized cobalt porphyrins were used as a model system for investigating catalytic activity in homogeneous and heterogeneous oxidation catalysis. Self-assembled monolayers of thiol-functionallized cobalt porphyrins were prepared on a gold surface and served as heterogeneous catalysts. These immobilized molecules prevented the strong inactivation observed for their homogeneous congener. As a result, the turnover number per molecule in heterogeneous catalysis was at least 100 times higher than that of the corresponding homogeneous catalyst. It is atypical for a heterogenized catalyst to outperform its homogeneous congener. The properties of the molecular layers were characterized on the molecular level by means of X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). The results demonstrate that the performance of these biomimetic catalysts can be dramatically improved if the catalyst arrangement can be controlled on the molecular level.

  • 5.
    Buijs, Jos
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Håkansson, Kristina
    Uppsala University, Sweden.
    Hagman, Charlotte
    Uppsala University, Sweden.
    Håkansson, Per
    Uppsala University, Sweden.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    A new method for the accurate determination of the isotopic state of single amide hydrogens within peptides using Fourier transform ion cyclotron resonance mass spectrometry2000In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, Vol. 14, no 19, p. 1751-1756Article in journal (Refereed)
    Abstract [en]

    A new method is presented to accurately determine the probability of having a deuterium or hydrogen atom on a specific amide position within a peptide after deuterium/hydrogen (D/H) exchange in solution. Amide hydrogen exchange has been proven to be a sensitive probe for studying protein structures and structural dynamics. At the same time, mass spectrometry in combination with physical fragmentation methods is commonly used to sequence proteins based on an amino acid residue specific mass analysis. In the present study it is demonstrated that the isotopic patterns of a series of peptide fragment ions obtained with capillary-skimmer dissociation, as observed with a 9.4 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer, can be used to calculate the isotopic state of specific amide hydrogens. This calculation is based on the experimentally observed isotopic patterns of two consecutive fragments and on the isotopic binomial distributions of the atoms in the residue constituting the difference between these two consecutive fragments. The applicability of the method is demonstrated by following the sequence-specific D/H exchange rate in solution of single amide hydrogens within some peptides.

  • 6.
    Buijs, Jos
    et al.
    Uppsala University, Sweden.
    Ramström, Margareta
    Uppsala University, Sweden.
    Danfelter, Mikael
    Uppsala University, Sweden.
    Larsericsdotter, Helén
    Mälardalen University, Department of Biology and Chemical Engineering.
    Håkansson, Per
    Mälardalen University, Department of Biology and Chemical Engineering.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Localized changes in the structural stability of myoglobin upon adsorption onto silica particles, as studied with hydrogen/deuterium exchange mass spectrometry2003In: Journal of Colloid and Interface Science, ISSN 0021-9797, Vol. 263, no 2, p. 441-448Article in journal (Refereed)
    Abstract [en]

    A new method is presented for monitoring the conformational stability of various parts of a protein that is physically adsorbed onto nanometer-sized silica particles. The method employs hydrogen/deuterium (H/D) exchange of amide hydrogens, a process that is extremely sensitive to structural features of proteins. The resulting mass increase is analyzed with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Higher structural specificity is obtained by enzymatically cleaving the adsorbed proteins prior to mass spectrometric analysis. The mass increases of four peptic fragments of myoglobin are followed as a function of the H/D exchange time. The four peptic fragments cover 90% of the myoglobin structure. Two of the peptic fragments, located in the middle of the myoglobin sequence and close to the heme group, do not show any adsorption-induced changes in their structural stability, whereas the more stable C- and N-terminal fragments are destabilized. Interestingly, for the N-terminal fragment, comprising residues 1–29, two distinct and equally large conformational populations are observed. One of these populations has a stability similar to that in solution (−23 kJ/mol), whereas the other population is highly destabilized upon adsorption (−11 kJ/mol).

  • 7.
    Ell, A.H.
    et al.
    Stockholm University, Sweden.
    Csjernyik, G.
    Stockholm University, Sweden.
    Slagt, V.F.
    Stockholm University, Sweden.
    Bäckvall, J.E.
    Stockholm University, Sweden.
    Berner, S.
    Uppsala University, Sweden.
    Puglia, C
    Uppsala University, Sweden.
    Ledung, G
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Oscarsson, S
    Mälardalen University, School of Sustainable Development of Society and Technology. Uppsala University, Sweden.
    Synthesis of thioacetate-functionalized cobalt(II) porphyrins and their immobilization on gold surface - Characterization by X-ray photoelectron spectroscopy2006In: European Journal of Organic Chemistry, ISSN 1434-193X, no 5, p. 1193-1199Article in journal (Refereed)
    Abstract [en]

    Cobalt tetraarylporphyrins 1-Co and 2-Co with thioacetate-functionalized carbon chains on the aryl groups were synthesized. The cobalt porphyrin 2-Co was immobilized on a gold surface after deprotection of the S-acetyl group. The immobilized porphyrin was studied by X-ray Photoelectron Spectroscopy (XPS) and the results suggest that a complete monolayer of porphyrins is formed.

  • 8.
    Gunnarsson, K
    et al.
    Uppsala University, Sweden.
    Roy, P.E.
    Uppsala University, Sweden.
    Felton, S.
    Uppsala University, Sweden.
    Pihl, J.
    Uppsala University, Sweden.
    Svedlindh, P.
    Uppsala University, Sweden.
    Berner, S
    Mälardalen University, Department of Biology and Chemical Engineering. Uppsala University, Sweden.
    Lidbaum, H.
    Uppsala University, Sweden.
    Oscarsson, S
    Mälardalen University, Department of Biology and Chemical Engineering. Uppsala University, Sweden.
    Programmable motion and separation of single magnetic particles on patterned magnetic surfaces2005In: Advanced Materials, ISSN 0935-9648, Vol. 17, no 14, p. 1730-1734Article in journal (Refereed)
    Abstract [en]

    Motion of single micrometer-sized magnetic particles on patterned magnetic surfaces is controlled by a rotating magnetic field (see Figure and cover). Patterns of thin-film magnetic elements are tailored to form transport lines. Individual particles are separated by adding junctions to the transport lines. The method can improve existing applications in biotechnology and generate new ones in life sciences.

  • 9.
    Göthelid, Emmanuelle
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Benito, N
    Universidad Miguel Hernández de Elche, Bio-Engineering Institute, Valencia KM.87, 03550 Alicante, Spain.
    Gonzalez, D
    Universidad Miguel Hernández de Elche, Bio-Engineering Institute, Valencia KM.87, 03550 Alicante, Spain.
    Fernandez, E
    Universidad Miguel Hernández de Elche, Bio-Engineering Institute, Valencia KM.87, 03550 Alicante, Spain.
    Granstam, Cecilia
    Mälardalen University, Department of Biology and Chemical Engineering.
    Chow, Winnie
    Mälardalen University, Department of Biology and Chemical Engineering.
    Geuens, D
    Uppsala University.
    Neves, H
    Uppsala University.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Hyaluronic acid Grafting on Silicon Surfaces: Towards an Increased Biocomp of Brain Micro-Electorde arrays2008In: 8th World Biomaterials Congress 2008, Volume 2, 2008, p. 1081-Conference paper (Other (popular science, discussion, etc.))
  • 10. Johansson, LarsErik
    et al.
    Gunnarsson, Klas
    Bijelovic, Stojanka
    Eriksson, Kristofer
    Surpi, Alessandro
    Gothelid, Emmanuelle
    Svedlindh, Peter
    Oscarsson, Sven
    A magnetic microchip for controlled transport of attomole levels of proteins2010In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 10, no 5, p. 654-661Article in journal (Refereed)
  • 11.
    Larsericsdotter, Helén
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Buijs, Jos
    Mälardalen University, Department of Biology and Chemical Engineering. Uppsala University, Sweden.
    Thermodynamic analysis of lysozyme adsorbed to silica2004In: Journal of colloid and interface science, ISSN 0021-9797, Vol. 276, no 2, p. 261-268Article in journal (Refereed)
    Abstract [en]

    The structural stability of hen egg white lysozyme in solution and adsorbed to small colloidal silica particles at various surface concentrations was investigated using hydrogen-deuterium (H/D) exchange in combination with mass spectrometry (HDX-MS) and differential scanning calorimetry (DSC). The combination of HDX-MS and DSC allows a full thermodynamic analysis of the lysozyme structure as both the enthalpy and the Gibbs free energy can be derived from the various measurements. Moreover, both HDX-MS and DSC provide information on the relative structural heterogeneity of lysozyme in the adsorbed state compared to that in solution. Results demonstrated that at high surface coverage, the structural stability of lysozyme was only marginally affected by adsorption to silica particles whereas the unfolding enthalpy decreased by more than 10%, meaning that the entropy of lysozyme increased with a similar value upon adsorption. Furthermore, the structural heterogeneity increased considerably. At lower surface concentrations, the structural heterogeneity increased further whereas the enthalpy of unfolding decreased. Further analyses of the HDX-MS experiments clearly indicated that folding/unfolding of lysozyme occurs through a two-domain process. These two domains had a similar amount of structural elements and a difference in stabilization energy of 8 kJ/mol, regardless if lysozyme was in solution or adsorbed to silica.

  • 12.
    Larsericsdotter, Helén
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Buijs, Jos
    Mälardalen University, Department of Biology and Chemical Engineering. Uppsala University,, Sweden.
    Thermodynamic Analysis of Proteins Adsorbed on Silica Particles: Electrostatic Effects.2001In: Journal of colloid and interface science, ISSN 0021-9797, Vol. 237, no 1, p. 98-103Article in journal (Refereed)
    Abstract [en]

    Electrostatic effects on protein adsorption were investigated using differential scanning calorimetry (DSC) and adsorption isotherms. The thermal denaturation of lysozyme, ribonuclease A (RNase), and alpha-lactalbumin in solution and adsorbed onto silica nanoparticles was examined at three concentrations of cations: 10 and 100 mM of sodium and 100 mM of sodium to which 10 mM of calcium was added. The parameters investigated were the denaturation enthalpy (DeltaH), the temperature at which the denaturation transition was half-completed (T(m)), and the temperature range of the denaturation transition. For lysozyme and RNase, adsorption isotherms depend strongly on the ionic strength. At low ionic strength both proteins have a high affinity for the silica particles and adsorption is accompanied by a 15-25% reduction in DeltaH and a 3-6 degrees C decrease in T(m), indicating that the adsorbed state of the proteins is destabilized. Also, an increase in the width of the denaturation transition is observed, signifying a larger conformational heterogeneity of the surface bound proteins. At higher ionic strengths, both with and without the addition of calcium, no significant adsorption-induced alteration in DeltaH was observed for all three proteins. The addition of calcium, however, decreases the width of the denaturation transition for lysozyme and RNase in the adsorbed state.

  • 13.
    Larseriksdotter, Helén
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Jansson, Östen
    Biacore AB, Sweden.
    Zhukov, Andrei
    Biacore AB, Sweden.
    Areskoug, Daphne
    Biacore AB, Sweden.
    Oscarsson, S
    Mälardalen University, Department of Biology and Chemical Engineering.
    Buijs, J
    Biacore AB, Sweden.
    Optimizing the surface plasmon resonance/mass spectrometry interface for functional proteomics applications2006In: Proteomics, ISSN 1615-9853, Vol. 6, no 8, p. 2355-2364Article in journal (Refereed)
    Abstract [en]

    A great challenge in functional or interaction proteomics is to map protein networks and establish a functional relationship between expressed proteins and their effects on cellular processes. These cellular processes can be studied by characterizing binding partners to a "bait" protein against a complex background of other molecules present in cells, tissues, or biological fluids. This so-called ligand fishing process can be performed by combining surface plasmon resonance biosensors with MS. This combination generates a unique and automated method to quantify and characterize biomolecular interactions, and identify the interaction partners. A general problem in chip-based affinity separation systems is the large surface-to-volume ratio of the fluidic system. Extreme care, therefore, is required to avoid nonspecific adsorption, resulting in losses of the target protein and carry-over during the affinity purification process, which may lead to unwanted signals in the final MS analysis and a reduction in sensitivity. In this study, carry-over of protein and low-molecular weight substances has been investigated systematically and cleaning strategies are presented. Furthermore, it is demonstrated that by the introduction of colloidal particles as a capturing and transporting agent, the recovery yield of the affinity-purified ligand could be improved nearly twofold.

  • 14.
    Larseriksdotter, Helén
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Oscarsson, S
    Mälardalen University, Department of Biology and Chemical Engineering.
    Buijs, J
    Biacore AB, Sweden.
    Structure Stability and Orientation of BSA Adsorbed to Silica2005In: Journal of Colloid and Interface Science, ISSN 0021-9797, Vol. 289, no 1, p. 26-35Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    In this investigation, the structure, stability, and orientation of bovine serum albumin (BSA) adsorbed onto silica particles were studied using differential scanning calorimetry (DSC) and limited proteolysis in combination with mass spectrometry (MS). DSC gave information on the overall structural stability of BSA while limited proteolysis was used to probe the accessibility of enzymatic cleavage sites, thereby yielding information on the orientation and structure of BSA adsorbed to silica surfaces. Thermal investigation of BSA in various buffers, both free in solution and in the adsorbed state, showed that solutes that surround the protein played an important role with respect to the overall structural stability and the structural heterogeneity of BSA. Limited proteolysis with trypsin and chymotrypsin indicated that BSA in the adsorbed state is oriented with domain 2 facing the silica surface. Also, upon adsorption, no additional cleavage sites were exposed. The combination of the results presented in this study implied that BSA molecules adsorbed onto silica particles were significantly reduced in their structural stability, but not to an extent that internal residues within the nativP structure became fully exposed to the solution.

  • 15.
    Ledung, Erika
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Eriksson, Per-Olov
    Mälardalen University, Department of Biology and Chemical Engineering.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    A strategic crossflow filtration methodology for the initial purification of promegapoietin from inclusion bodies2009In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 141, no 1-2, p. 64-72Article in journal (Refereed)
    Abstract [en]

    A novel crossflow filtration methodology is demonstrated for the initial purification of the therapeutic protein, promegapoietin-1a (PMP), produced as inclusion bodies (IBs) in a recombinant Escherichia coli bioprocess. Two strategic separation steps were performed by utilizing a filtration unit with a 1000 kDa polyethersulphone membrane. The first step, aiming for separation of soluble contaminants, resulted in a 50% reduction of the host cell proteins, quantified by total amino acid analysis and a 70% reduction of all DNA, quantified by fluorometry, when washing the particulate material with a 10 mM EDTA in 50 mM phosphate buffer, pH 8. The second step, aiming for separation of particulate contaminants from solubilized IBs, resulted in a 97-99.5% reduction of endotoxin, used as a marker for cell debris, and was quantified by the kinetic turbidimetric LAL endotoxin assay. The overall PMP yield was 58% and 33% respectively for the two solubilizations investigated, guanidine hydrochloride and arginine, as measured by RP-HPLC. The scope was also to investigate the physical characteristics of the intermediate product/s with regard to the choice of 113 solvent. Preliminary results from circular dichroism spectroscopy measurements indicate that the protein secondary structure was restored when arginine was used in the second step.

  • 16.
    Ledung, G.
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Bergkvist, M.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Quist, A.P.
    Uppsala University, Sweden.
    Gelius, U.
    Uppsala University, Sweden.
    Carlsson, J.
    Uppsala University, Sweden.
    Oscarsson, S.
    Uppsala University, Sweden.
    Novel method for preparation of disulfides on silicon2001In: Langmuir, ISSN 0743-7463, Vol. 17, no 2, p. 6056-6058Article in journal (Refereed)
    Abstract [en]

    This work describes an efficient novel method to incorporate reactive disulfide bonds onto a silica surface under mild reaction conditions. The reactive thiol groups introduced onto the silicon surface in the first reaction step will be oxidized but easily converted into highly reactive thiopyridyl groups, which can therefore easily be utilized for further organic synthesis involving thiol-containing molecules. This is done in a way that yields approximately a monolayer of reactant on the surface, thereby not adding to the roughness of the surface, of special importance, for instance, for single molecule interaction studies.

  • 17.
    Ledung, G.
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Gothelid, E.
    Berner, S.
    Backvall, J.E.
    Puglia, C.
    Oscarsson, S.
    The performance of a biomimetic oxidation catalyst immobilized on silicon wafers: A comparison with the catalyst in solution and immobilized on goldManuscript (Other academic)
  • 18.
    Ledung, Greger
    et al.
    Mälardalen University.
    Göthelid, Emmanuelle
    Mälardalen University. Uppsala University, Sweden.
    Berner, Simon
    University of Zurich, Switzerland.
    Bäckvall, Jan-E.
    Stockholm University, Sweden.
    Puglia, Carla
    Uppsala University, Sweden.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    The Performance of a Biomimetic Oxidation Catalyst Immobilised on Gold and Silica Substrates2007In: International Symposium on Relations between Homogeneous and Heterogeneous Catalysis: Abstracts / [ed] Gabor Somorjai, 2007, p. 180-Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Thiol-functionalized cobalt porphyrins were used as a model system for investigating catalytic activity in homo-geneous and heterogeneous oxidation catalysis. Self-assembled monolayers of thiol-functionalized cobalt porphyrins were prepared on a gold surface and served as heterogeneous catalysts. The immobilization of the molecules prevented the strong inactivation observed for their homogeneous congener. As a result, the turnover number permolecule in heterogeneous catalysis was at least 100 times higher than that of the corresponding homogeneouscatalyst. It is atypical for a heterogenized catalyst to outperform its homogeneous congener. The properties of themolecular layers were characterized on the molecular level by means of X-ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). The results demonstrate that the performance of these biomimetic catalysts can be dramatically improved if the catalyst arrangement can be controlled on the molecular level. In order to further investigate the influence of the substrate on the catalytic performance, monolayers of the cobalt porphyrins were grafted onto silica surfaces. The observed catalytic activity together with the surface analytical results are interpreted in relation to the supporting substrate. Preliminary results from this investigation (silicon wafer) show that the catalytic activity is similar to that of gold substrates.

  • 19.
    Oscarsson, S
    Mälardalen University, Department of Biology and Chemical Engineering.
    Programmable Motion and Separation of Single Magnetic Particles on Patterned Magnetic Surfaces2005In: Proceedings of, 2005Conference paper (Refereed)
  • 20.
    Oscarsson, S
    Mälardalen University, Department of Biology and Chemical Engineering.
    Separation of Single magnetic Particles for Life Science Application2005In: Proceedings of European Conference on Biomaterials, 2005Conference paper (Refereed)
  • 21.
    Oscarsson, S
    Uppsala University, Sweden.
    Special Invited Lectures: Surface Nano-Biotechnology2007In: The 2nd Annual IEEE International Conference on Nano/Micro Engineered and Molecualr System, 2007, p. 82-83Conference paper (Refereed)
    Abstract [en]

    With the intention to develop alternative approaches to lab on a chip for organisation and transport of biomolecules on surfaces several unique concepts have been developed. Electro contact printing (1) is a method with the potential to site specifically organise molecules at tenth of nanometers. This method has also been used for segmented derivatisation of micron sized magnetic beads. Controlled transport of magnetic beads on surfaces is a new technological platform (2) with a great potential for Surface Nanobiotechnology as macromolecule and cell transporter, cell and macromolecule sorter and nanosensor for studies of friction and quantification of macromolecules. (1) Nanoscale Site-Specific Immobilisation of Proteins through Electroactivated Disulphide Exchange Nanoletters (2003) Vol.3, No.6, pp. 779-781 (2) Programmable Motion of Magnetic Beads using Thin Film Magnetic Elements Advanced Materials, (2005) 17, 1730-1736.

  • 22.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Factors affecting protein interaction at sorbent interfaces1997In: Journal of Chromatography B: Biomedical Applications, ISSN 1572-6495, Vol. 699, no 1-2, p. 117-131Article in journal (Refereed)
    Abstract [en]

    Interactions between surfaces and macromolecules are the fundamentals in separation and detection of diverse solutes. In this very brief review the central aspects of protein-surface interactions are discussed with the intention of identifying the important factors influencing such processes and placing them in relation to the established knowledge in this field. Some perspectives of new techniques related to scanning probe microscopy for studying interactions at the nanometer level are also discussed.

  • 23.
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Influence of salts on protein interactions at interfaces of amphiphilic polymers and adsorbents1995In: J Chromatogr B Biomed Appl, ISSN 0378-4347, Vol. 666, no 1, p. 21-31Article in journal (Refereed)
    Abstract [en]

    The protein-binding capacity of two different amphiphilic adsorbents was investigated to determine the effect of solvent additives on the binding of proteins in hydrophobic-interaction chromatography. There was no simple correlation between binding capacity and the lyotropic series such as those suggested by the two different theories proposed by Arakawa and Narhi and Melander and Horvath. Proteins are known to be dynamic flexible objects which continuously undergo changes in conformation and which may well be influenced by chaotropic salts. Are conformational changes of proteins at interfaces an important parameter involved in protein interactions with amphiphilic polymers and adsorbents? In an attempt to answer this question, the reactivity of the thiol group in human serum albumin (HSA) toward N-ethyl-3-(2-pyridyldisulfanyl)propionamide dextran was used as a model system to evaluate its correlation with the lyotropic series. The results indicate that the thiol-disulfide exchange reaction at interfaces of amphiphilic polymers is influenced by the type of salt used.

  • 24.
    Oscarsson, Sven
    et al.
    Mälardalen University, Department of Biology and Chemical Engineering.
    Kårsnäs, Per
    PerCreative, Gothenburg, Sweden.
    Salt-promoted adsorption of proteins onto amphiphilic agarose-based adsorbents. II. Effects of salt and salt concentration1998In: Journal of Chromatography A, ISSN 0021-9673, Vol. 803, no 1-2, p. 83-93Article in journal (Refereed)
    Abstract [en]

    The effects of different types of salts and salt concentrations on the selectivity in the adsorption of serum proteins have been compared for the amphiphilic agarose-based adsorbents Phenyl-Sepharose, Octyl-Sepharose, butyl-agarose and mercaptopyridine-derivatized agarose. By use of multivariate analysis, the complex interrelationships for the different combined effects were evaluated. From these analyses conclusions about similarities and/or dissimilarities in the mechanisms involved in adsorption of proteins on respective adsorbent were made.

  • 25. Quist, Arjan P.
    et al.
    Pavlovic, Elisabeth
    Oscarsson, Sven
    Mälardalen University, Department of Biology and Chemical Engineering.
    Recent advances in microcontact printing2005In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 381, no 3, p. 591-600Article in journal (Refereed)
    Abstract [en]

    Microcontact printing is a remarkable surface patterning technique. Developed about 10 years ago, it has triggered enormous interest from the surface science community, as well as from engineers and biologists. The last five years have been rich in improvements to the microcontact printing process itself, as well as in new technical innovations, many designed to suit new applications. In this review, we describe the evolution of microcontact printing over the past five years. The review is categorized into three main sections: the improvements made to the technique, new variations, and new applications.

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