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  • 251. Delgado-Barrio, Gerardo
    et al.
    Maruani, Jean
    Piecuch, Piotr
    Brändas, Erkki
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Special Issue: Proceedings from the Fourteenth European Workshop on Quantum Systems in Chemistry and Physics Preface2011In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 111, no 2, p. 203-204Article in journal (Other academic)
  • 252.
    Dew, Noel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Edsman, Katarina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Gel formation in systems composed of drug containing catanionic vesicles and oppositely charged hydrophobically modified polymer.2009In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 70, no 2, p. 187-197Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to explore if mixtures of drug containing catanionic vesicles and polymers give rise to gel formation, and if so, if drug release from these gels could be prolonged. Catanionic vesicles formed from the drug substances alprenolol or tetracaine, and the oppositely charged surfactant sodium dodecyl sulphate were mixed with polymers. Three polymers with different properties were employed: one bearing hydrophobic modifications, one positively charged and one positively charged polymer bearing hydrophobic modifications. The structure of the vesicles before and after addition of polymer was investigated by using cryo-TEM. Gel formation was confirmed by using rheological measurements. Drug release was studied using a modified USP paddle method. Gels were observed to form only in the case when catanionic vesicles, most likely with a net negative charge, were mixed with positively charged polymer bearing lipophilic modifications. The release of drug substance from these systems, where the vesicles are not trapped within the gel but constitute a founding part of it, could be significantly prolonged. The drug release rate was found to depend on vesicle concentration to a higher extent than on polymer concentration.

  • 253.
    Dew, Noel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Eriksson, Jonny
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Edsman, Katarina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Björk, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Gel formulations containing catanionic vesicles composed of alprenolol and SDS: effects of drug release and skin penetration on aggregate structure2012In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 89, p. 53-60Article in journal (Refereed)
    Abstract [en]

    To fully utilize the extended contact time of gel formulations a novel formulation with drug containing catanionic aggregates offering prolonged drug release and skin penetration were investigated. This study aimed to further explore the drug release process from catanionic vesicles in gels. Catanionic vesicles were formed from alprenolol and sodium dodecyl sulphate. Physical gels composed of catanionic vesicles and a SoftCAT polymer were used as well as covalent Carbopol gels. Drug release was measured in vitro using a modified USP paddle method and the skin penetration was studied using dermatomized pig ear skin mounted in horizontal Ussing chambers. The aggregate structure was visualized with cryo-TEM during the drug release and skin penetration process. The study results show that catanionic vesicles are present in the formulations throughout the drug release process and during the clinically relevant skin application time. Hence, the decreased skin penetration rate stems from the prolonged release of drug substance from the gels. The rheological investigation shows that the gel structure of the physically cross-linked gels is maintained even as the drug substance is released and the gel volume is decreased.These findings indicate that the applicability of formulations like these is a future possibility.

  • 254. Dos Santos, N.
    et al.
    Cox, K. A.
    McKenzie, C. A.
    van Baarda, E.
    Gallagher, B. C.
    Karlsson, G.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Edwards, K.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Mayer, L. D.
    Allen, C.
    Bally, M. B.
    Ph gradient loading of anthracyclines into cholesterol-free liposomes: Enhancing drug loading rates through use of ethanol2004In: Journal of Investigative Medicine, Vol. 52, no 1, p. S158-S158Article in journal (Refereed)
  • 255. Dos Santos, Nancy
    et al.
    Allen, Christine
    Doppen, Anne-Marie
    Anantha, Malathi
    Cox, Kelly A K
    Gallagher, Ryan C
    Karlsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Kenner, Gail
    Samuels, Lacey
    Webb, Murray S
    Bally, Marcel B
    Influence of poly(ethylene glycol) grafting density and polymer length on liposomes: Relating plasma circulation lifetimes to protein binding2007In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1768, no 6, p. 1367-1377Article in journal (Refereed)
    Abstract [en]

    The incorporation of poly(ethylene glycol) (PEG)-conjugated lipids in lipid-based carriers substantially prolongs the circulation lifetime of liposomes. However, the mechanism(s) by which PEG-lipids achieve this have not been fully elucidated. It is believed that PEG-lipids mediate steric stabilization, ultimately reducing surface-surface interactions including the aggregation of liposomes and/or adsorption of plasma proteins. The purpose of the studies described here was to compare the effects of PEG-lipid incorporation in liposomes on protein binding, liposome-liposome aggregation and pharmacokinetics in mice. Cholesterol-free liposomes were chosen because of their increasing importance as liposomal delivery systems and their marked sensitivity to protein binding and aggregation. Specifically, liposomes containing various molecular weight PEG-lipids at a variety of molar proportions were analyzed for in vivo clearance, aggregation state (size exclusion chromatography, quasi-elastic light scattering, cryo-transmission and freeze fracture electron microscopy) as well as in vitro and in vivo protein binding. The results indicated that as little as 0.5 mol% of 1,2-distearoyl-sn-glycero-3-phosphatidylethanolamine (DSPE) modified with PEG having a mean molecular weight of 2000 (DSPE-PEG(2000)) substantially increased plasma circulation longevity of liposomes prepared of 1,2-distearoyl-sn-glycero-3-phosphatidylcholine (DSPC). Optimal plasma circulation lifetimes could be achieved with 2 mol% DSPE-PEG(2000). At this proportion of DSPE-PEG(2000), the aggregation of DSPC-based liposomes was completely precluded. However, the total protein adsorption and the protein profile was not influenced by the level of DSPE-PEG(2000) in the membrane. These studies suggest that PEG-lipids reduce the in vivo clearance of cholesterol-free liposomal formulations primarily by inhibition of surface interactions, particularly liposome-liposome aggregation.

  • 256. Dos Santos, Nancy
    et al.
    Cox, Kelly A
    McKenzie, Cheryl A
    van Baarda, Floris
    Gallagher, Ryan C
    Karlsson, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Edwards, Katarina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Mayer, Lawrence D
    Allen, Christine
    Bally, Marcel B
    pH gradient loading of anthracyclines into cholesterol-free liposomes: enhancing drug loading rates through use of ethanol.2004In: Biochim Biophys Acta, ISSN 0006-3002, Vol. 1661, no 1, p. 47-60Article in journal (Refereed)
  • 257. Dos Santos, Nancy
    et al.
    Waterhouse, Dawn
    Masin, Dana
    Tardi, Paul
    Karlsson, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Edwards, Katarina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Bally, Marcel
    Substantial increases in idarubicin plasma concentration by liposome encapsulation mediates improved antitumor activity.2005In: J Control Release, ISSN 0168-3659, Vol. 105, no 1-2, p. 89-105Article in journal (Refereed)
  • 258. Drescher, Simon
    et al.
    Meister, Annette
    Blume, Alfred
    Karlsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Almgren, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Dobner, Bodo
    General Synthesis and Aggregation Behaviour of a Series of Single-Chain 1,ω-Bis(phosphocholines)2007In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, no 18, p. 5300-5307Article in journal (Refereed)
    Abstract [en]

    The synthesis and physicochem. characterization of a series of polymethylene-1,w-bis(phosphocholines) with even-numbered chain lengths between 22 and 32 carbon atoms is described. Two new synthetic strategies for the prepn. of long-chain 1,wo-diols as hydrocarbon building blocks are presented. The temp.-dependent self-assembly of the single-chain bolaamphiphiles was investigated by cryo transmission electron microscopy (cryo-TEM), differential scanning calorimetry (DSC), and Fourier transform IR spectroscopy (FTIR).

  • 259.
    Dunkel, M., Tri, N., Beckett, R., and Caldwell, K.D.
    Uppsala University, Centre for Surface Biotechnology.
    Electrical FFF: A Tool for Characterization of Colloidal Adsorption Complexes1997In: J. Microcol. Sep., Vol. 9, p. 177-183Article in journal (Refereed)
  • 260.
    Dunn, Halina K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Westin, Per-Oskar
    Staff, Daniel R.
    Peter, Laurence M.
    Waker, Alison B.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Determination of the Electron Diffusion Length in Dye-Sensitized Solar Cells by Substrate Contact Patterning2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 28, p. 13932-13937Article in journal (Refereed)
    Abstract [en]

    A new method to estimate the electron diffusion length in dye-sensitized solar cells (DSCs) is presented. DSCs were fabricated on conducting glass substrates that were patterned by laser ablation of the fluorine-doped tin oxide coating to form parallel contact strips separated by uncontacted strips of the same width. The relative collection efficiency was measured as a function of the gap between the contact strips, which determines the lateral distance traveled by electrons to reach the contacts. To avoid complications arising from non-linear recombination kinetics, current measurements were performed using small amplitude perturbations of the electron density close to open circuit and the maximum power point to minimize electron density gradients in the film. One and two-dimensional solutions of the continuity equation for electron transport and back reaction predict that the relative collection efficiency should fall as spacing between the contact strips exceeds the electron diffusion length and electrons are lost by back electron transfer during transit to the contacts. Measurements of the relative collection efficiency were fitted to the predicted dependence of the collection efficiency on the spacing between the contact strips to obtain the value of the electron diffusion length. The diffusion length is found to increase with voltage both at open circuit and at the maximum power point.

  • 261. Dunne, Lawrence J.
    et al.
    Brändas, Erkki J.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Kvantkemi.
    Two-fluid Model of Superconducting Condensates and Spin Gaps in dx2-dy2 Wave High Tc Cuprates from Repulsive Electronic Correlations2004In: International Journal of Quantum Chemistry, ISSN 0020-7608, Vol. 99, p. 798-804Article in journal (Refereed)
  • 262.
    Durbeej, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    On the primary event of phytochrome: quantum chemical comparison of photoreactions at C4, C10 and C152009In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, no 9, p. 1354-1361Article in journal (Refereed)
    Abstract [en]

    Phytochromes are widespread photoreceptors responsive to red and far-red light that exist in two photochromic forms Pr (inactive) and Pfr (active). The Pr → Pfr conversion proceeds through a series of events initiated by ZE photoisomerization of the tetrapyrrole chromophore, believed to occur at C15 of the methine bridge between rings C and D. Recent crystal structures show that ring D in Pr is less tightly packed by the protein than rings A, B and C, which should favor the C15 reaction over reactions at C4 (AB methine bridge) and C10 (BC). In the present work, quantum chemical methods are used to establish the intrinsic reactivity of the chromophore towards all three possible ZE isomerization events in the absence of steric effects and specific interactions with the protein. Using a level of theory that reproduces spectroscopic data with an accuracy of 0.2 eV, it is demonstrated that isolated conditions allow the C10 photoreaction to substantially dominate. This finding suggests that the different degrees of ring-packing observed in the protein are crucial not only to facilitate a reaction at C15, but also to prevent an intrinsically more favorable reaction at C10 from taking place.

  • 263. Durbeej, Bo
    et al.
    Borg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Eriksson, Leif
    Computational evidence in favor of a protonated chromophore in the photoactivation of phytochrome2005In: Chemical Physics Letters, Vol. 416, p. 83-Article in journal (Refereed)
  • 264. Durbeej, Bo
    et al.
    Borg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Eriksson, Leif
    Phytochromobilin C15-Z,syn -> C15-E,anti isomerization: concerted or stepwise?2004In: Physical Chemistry Chemical Physics, Vol. 6, p. 5066-Article in journal (Refereed)
  • 265.
    Durbeej, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Sandala, Gregory M.
    Bucher, Denis
    Smith, David M.
    Radom, Leo
    On the importance of ribose orientation in the substrate activation of the coenzyme B12-dependent mutases2009In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 34, p. 8578-8585Article in journal (Refereed)
    Abstract [en]

    The degree to which the corrin ring portion of coenzyme B-12 can   facilitate the H-atom-abstraction step in the glutamate mutase   (GM)-catalyzed reaction of (S)-glutamate has been investigated with   density functional theory. The crystal structure of GM identifies two   possible orientations of the ribose portion of coenzyme B-12. In one orientation (A), the OH groups of the ribose extend away from the   corrin ring, whereas in the other orientation (B) the OH groups, especially that involving O3', are instead directed towards the corrin   ring. Our calculations identify a sizable stabilization amounting to   about 30kJ mol(-1) in the transition structure (TS) complex   corresponding to orientation B (TS(B)Corlm). In the TS complex where   the ribose instead is positioned in orientation A, no such effect is   manifested. The observed stabilization in TS(B)CorIm appears to be the   result of favorable interactions involving O3' and the corrin ring,   including a C-H center dot center dot center dot O hydrogen bond. We   find that the degree of stabilization is not particularly sensitive to   the Co-C distance. Our calculations show that any potential   stabilization afforded to the H-atom-abstraction step by coenzyme B12   is sensitive to the orientation of the ribose moiety.

  • 266.
    Díaz, T., Ståhl, U., Batista-Viera, F. and Carlsson, J.
    Uppsala University, Centre for Surface Biotechnology.
    Reversible immobilization of chemically modified Pullulanase1995In: Biotechnology Techniques, Vol. 9, no 7, p. 533-538Article in journal (Refereed)
  • 267.
    Ebbestad, Jan Ove R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Early Paleozoic gastropods of Anticosti Island, Gulf of St. Lawrence; outline of project2001In: Geological Association of Canada/Mineralogical Association of Canada Joint Annual Meeting, Memorial University, St. John's, Newfoundland, May 27-30 2001, 2001, p. 40-Conference paper (Other (popular science, discussion, etc.))
  • 268.
    Edström, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Fundamental Studies on Peak Shapes in Liquid Chromatography2010Licentiate thesis, comprehensive summary (Other academic)
  • 269.
    Edström, Lena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Samuelsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Fornstedt, Torgny
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Deformations of overloaded bands under pH-stable conditions in reversed phase chromatography2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 15, p. 1966-1973Article in journal (Refereed)
    Abstract [en]

    It has recently been demonstrated, using mathematical models, how peculiar overloaded band profiles of basic compounds are due to the local pH in the column when using low capacity buffers. In this study, overloaded peak shapes resulting after injection of carefully pH matched samples close to the pK(a) of the chosen solute are investigated primarily on two columns; one hybrid silica C18 column (Kromasil Eternity) and one purely polymeric column (PLRP-S), the latter lacking C18 ligands. It was found that distorted peaks of the basic test compound appear even though there is no difference in pH between the injected sample solution and the eluent; the previous explanation to why these effects occur is based on a pH mismatch. Thus, the unusual band shapes are not due to an initial pH difference. Furthermore, it was observed that the effect does not appear on polymeric columns without C18 ligands, but only on columns with C18 ligands, independently of the base matrix (silica, hybrid silica, polymeric).

  • 270.
    Edvardsson, David
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Quantum Chemistry. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. QUANTUM CHEMISTRY.
    Lunell, Sten
    Marian, Christel M.
    Calculation of potential energy curves for Rb2 including relativistic effects2003In: Molecular Physics, Vol. 101, no 15, p. 2381-2389Article in journal (Refereed)
  • 271.
    Edvinsson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Elvingson, Christer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Arteca, Gustavo
    Effect of compression on the molecular shape of polymer mushrooms with variable stiffness2002In: Journal of chemical physics, Vol. 116, p. 9510-Article in journal (Refereed)
  • 272.
    Edvinsson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Pschirer, Niel
    Schöneboom, Jan
    Eickemeyer, Felix
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Photoinduced electron transfer from a terrylene dye to TiO2: Quantification of band edge shift effects2009In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 357, no 1-3, p. 124-131Article in journal (Refereed)
    Abstract [en]

    A terrylene chromophore exhibiting a high extinction coefficient has been developed as a sensitizer for photovoltaic applications. The photophysical and photochemical properties of the dye were analyzed both experimentally and theoretically. Terrylene-sensitized nanocrystalline TiO2 solar cells yielded good photocurrents providing more than 60% in external quantum efficiency. The photoinduced electron transfer from the dye to TiO2 was found to be very sensitive to conduction band edge shifts in TiO2 induced, either by changes in the composition of the redox electrolyte or by UV-illumination. This sensitivity was observed in quantum efficiencies for photocurrent generation of terrylene-sensitized solar cells and in photoinduced absorption experiments. The conduction band shifts were quantified using charge extraction methods. The observed sensitivity of the injection efficiency suggests that photoinduced electron transfer occurs from the relaxed excited state, possibly due to poor electronic coupling between TMIMA excited states and TiO2 conduction band states.

  • 273.
    Edwards, Katarina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Johnsson, M
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Karlsson, G
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Silvander, M
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Effect of polyethyleneglycol-phospholipids on aggregate structure in preparations of small unilamellar liposomes1997In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 73, no 1, p. 258-266Article in journal (Other academic)
    Abstract [en]

    Phospholipids with covalently attached poly(ethylene glycol) (PEG lipids) are commonly used for the preparation of long circulating liposomes. Although it is well known that lipid/PEG-lipid mixed micelles may form above a certain critical concentration of PEG-lipid, little is known about the effects of PEG-lipids on liposome structure and leakage at submicellar concentrations. In this study we have used cryogenic transmission electron microscopy to investigate the effect of PEG(2000)-PE on aggregate structure in preparations of liposomes with different membrane compositions. The results reveal a number of important aggregate structures not documented before. The micrographs show that enclosure of PEG-PE induces the formation of open bilayer discs at concentrations well below those where mixed micelles begin to form. The maximum concentration of PEG-lipid that may be incorporated without alteration of the liposome structure depends on the phospholipid chain length, whereas phospholipid saturation or the presence of cholesterol has little or no effect. The presence of cholesterol does, however, affect the shape of the mixed micelles formed at high concentrations of PEG-lipid. Threadlike micelles form in the absence of cholesterol but adapt a globular shape when cholesterol is present.

  • 274.
    Edwards, M O M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Andersson, M
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Gruszecki, T
    Pettersson, H
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Thunman, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thuraisingham, G
    Vestling, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hagfeldt, A
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Charge-discharge kinetics of electric-paint displays2004In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 565, no 2, p. 175-184Article in journal (Refereed)
  • 275.
    Egyed L., Ballagi-Pordany A., Bartha A. and Belak, S.
    Uppsala University, Centre for Surface Biotechnology.
    Studies of in vivo distribution of bovine herpesvirus type 4 in the natural host1996In: J Clin Microbiol, Vol. 34, no 5, p. 1091-1095Article in journal (Refereed)
  • 276.
    Ehteshami, G.R., Porath, J. and Guzman, R.Z.
    Uppsala University, Centre for Surface Biotechnology.
    Interactions and Applications of Soluble Heterobifunctional Affinity Chelating Polymers in Immobilized Metal Affinity Chromatography1996In: J. Mol Recog., Vol. 9, p. 733-737Article in journal (Refereed)
  • 277.
    Ek, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Li, Jin-Ping
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Pettersson, Gunilla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Gong, Feng
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Identification and characterization of a mammalian 14-kDa phosphohistidine phosphatase2002In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 269, p. 5016-5023Article in journal (Refereed)
    Abstract [en]

    Protein histidine phosphorylation in eukaryotes has beensparsely studied compared to protein serine/threonine andtyrosine phosphorylation. In an attempt to rectify this byprobing porcine liver cytosol with the phosphohistidinecontainingpeptide succinyl-Ala-His(P)-Pro-Phe-p-nitroanilide(phosphopeptide I), we observed a phosphataseactivity that was insensitive towards okadaic acid andEDTA. This suggested the existence of a phosphohistidinephosphatase different from protein phosphatase 1, 2Aand 2C. A 1000-fold purification to apparent homogeneitygave a 14-kDa phosphatase with a specific activity of 3lmolÆmin)1Æmg)1 at pH 7.5 with 7 lM phosphopeptide Ias substrate. Partial amino-acid sequence determination ofthe purified porcine enzyme by MS revealed similaritywith a human sequence representing a human chromosome9 gene of hitherto unknown function. Molecularcloning from a human embryonic kidney cell cDNAlibraryfollowed by expression and purification, yielded aprotein with a molecular mass of 13 700 Da, and anEDTA-insensitive phosphohistidine phosphatase activityof 9 lmolÆmin)1Æmg)1 towards phosphopeptide I. Nodetectable activity was obtained towards a set of phosphoserine-,phosphothreonine-, and phosphotyrosine peptides.Northern blot analysis indicated that the humanphosphohistidine phosphatase mRNA was present preferentiallyin heart and skeletal muscle. These resultsprovide a new tool for studying eukaryotic histidinephosphorylation/dephosphorylation.

  • 278.
    Ekegren, Titti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Hanrieder, Jörg
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Aquilonius, Sten-Magnus
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Focused proteomics in post-mortem human spinal cord2006In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 5, no 9, p. 2364-2371Article in journal (Refereed)
    Abstract [en]

    With a highly sensitive electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS) system, proteins were identified in minimal amounts of spinal cord from patients with the neurodegenerative disease amyotrophic lateral sclerosis (ALS) and compared to proteins in spinal cord from control subjects. The results show 18 versus 16 significantly identified ( p < 0.05) proteins, respectively, all known to be found in the central nervous system. The most abundant protein in both groups was the glial fibrillary acidic protein, GFAP. Other proteins were, for example, hemoglobin alpha- and, chain, myelin basic protein, thioredoxin, R enolase, and cholin acetyltransferase. This study also includes the technique of laser microdissection in combination with pressure catapulting (LMPC) for the dissection of samples and specific neurons. Furthermore, complementary experiments with nanoLC-matrix assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-TOF MS) confirmed the results of the ESI-FTICR MS screening and provided additional results of further identified proteins.

  • 279.
    Ekegren, Titti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Hanrieder, Jörg
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Clinical perspectives of high-resolution mass spectrometry-based proteomics in neuroscience: Exemplified in amyotrophic lateral sclerosis biomarker discovery research2008In: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 43, no 5, p. 559-571Article in journal (Refereed)
    Abstract [en]

    Biomarker discovery is a central application in today's proteomic research. There is an urgent need for valid biomarkers to improve diagnostic tools and treatment in many disorders, such as the rapidly progressing neurodegenerative disorder amyotrophic lateral sclerosis (ALS) that has a fatal outcome in about 3 years and yet no curative treatment. Screening for clinically relevant biomarkers puts high demands on high-throughput, rapid and precise proteomic techniques. There is a large variety in the methods of choice involving mainly gel-based approaches as well as chromatographic techniques for multi-dimensional protein and peptide separations followed by mass spectrometry (MS) analysis. This special feature article will discuss some important aspects of MS-based clinical proteomics and biomarker discovery in the field of neuro degenerative diseases and ALS research respectively, with the aim to provide a prospective view on current and future research aspects in the field. Furthermore, examples for application of high-resolution MS-based proteomic strategies for ALS biomarker discovery will be demonstrated with two studies previously reported by our group. These studies include among others, utilization of capillary liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR-MS) for advanced protein pattern classification in cerebrospinal fluid (CSF) samples of ALS patients as well as highly sensitive protein identification in minimal amounts of postmortem spinal cord tissue and laser micro-dissected motor neurons using FT-ICR-MS in conjunction with nanoflow LC coupled to matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (LC-MALDI-TOF-TOF-MS).

  • 280.
    Ekert, Artur
    et al.
    Centre for Quantum Computation, Univ.of Oxford, UK.
    Ericsson, Marie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Hayden, Patrick
    Centre for Quantum Computation, Univ.of Oxford, UK.
    Inamori, H.
    Centre for Quantum Computation, Univ.of Oxford, UK.
    Jones, Jonathan A.
    Centre for Quantum Computation, Univ.of Oxford, UK.
    Oi, Daniel K.L.
    Centre for Quantum Computation, Univ.of Oxford, UK.
    Vedral, Vlatko
    Centre for Quantum Computation, Univ.of Oxford, UK.
    Geometric Quantum Computation2000In: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 47, no 14-15, p. 2501-2513Article in journal (Refereed)
    Abstract [en]

    We describe in detail a general strategy for implementing a conditional geometric phase between two spins. Combined with single-spin operations, this simple operation is a universal gate for quantum computation, in that any unitary transformation can be implemented with arbitrary precision using only single-spin operations and conditional phase shifts. Thus quantum geometrical phases can form the basis of any quantum computation. Moreover, as the induced conditional phase depends only on the geometry of the paths executed by the spins it is resilient to certain types of errors and offers the potential of a naturally fault-tolerant way of performing quantum computation.

  • 281. Ekert, Artur
    et al.
    Ericsson, Marie
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Quantum Chemistry. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Quantum Chemistry.
    Hayden, Patrick
    Inamori, Hitoshi
    Jones, Jonathan A.
    Oi, Daniel K.L.
    Vedral, Vlatko
    Geometric quantum computation2000In: Journal of Modern Optics, Vol. 47, p. 2501-Article in journal (Refereed)
    Abstract [en]

    We describe in detail a general strategy for implementing a conditional geometric phase between two spins. Combined with single-spin operations, this simple operation is a universal gate for quantum computation, in that any unitary transformation can be implemented with arbitrary precision using only single-spin operations and conditional phase shifts. Thus quantum geometrical phases can form the basis of any quantum computation. Moreover, as the induced conditional phase depends only on the geometry of the paths executed by the spins it is resilient to certain types of errors and offers the potential of a naturally fault-tolerant way of performing quantum computation.

  • 282.
    Eklund, Birgitta I.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Moberg, My
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Mannervik, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Divergent activities of human glutathione transferases in the bioactivation of azathioprine2006In: Molecular Pharmacology, ISSN 0026-895X, E-ISSN 1521-0111, Vol. 70, no 2, p. 747-754Article in journal (Refereed)
    Abstract [en]

    Azathioprine is a thiopurine prodrug clinically used for immunosuppression in the treatment of inflammatory diseases and in pharmacological regimens of organ transplantations. Its pharmacological action is based on the release of 6-mercaptopurine, but the biochemical processes underlying this biotransformation have remained obscure. In this investigation, human glutathione transferases (GSTs) from seven distinct classes were assayed with azathioprine. GSTs A1-1, A2-2, and M1-1, all abundantly expressed in human liver, displayed the highest activity among the 14 GSTs tested. The uncatalyzed reaction of azathioprine with glutathione was estimated to be less than 1% of the GST-catalyzed biotransformation. GST M1-1 is polymorphic with a frequently occurring null allele, and GSTs A1-1 and A2-2 show variable expression levels in human subjects, implying significant differences in the rate of 6-mercaptopurine release from azathioprine. Individuals expressing high GST activity are apparently predisposed for adverse reactions to azathioprine treatment, both by promoting excessively high concentrations of free 6-mercaptopurine and its toxic metabolites and by depleting cellular glutathione. These novel aspects of GST-dependent azathioprine biotransformation have not been considered previously.

  • 283. Ekman, Anna
    et al.
    Campos, Monica
    Lindahl, Sofia
    Co, Michelle
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Borjesson, Pal
    Karlsson, Eva Nordberg
    Turner, Charlotta
    Bioresource utilisation by sustainable technologies in new value-added biorefinery concepts - two case studies from food and forest industry2013In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 57, p. 46-58Article in journal (Refereed)
    Abstract [en]

    This paper presents a trans-disciplinary assessment of new and innovative biorefinery concepts producing high-value chemical compounds from residues from agriculture, food and forest industries. There is a significant potential of biomass residues in Sweden suitable for the extraction of various compounds, including upgrading by biocatalytic processes, in addition to current energy generation. Two examples presented are quercetin extracted from onion waste by pressurised hot water in conjunction with enzymatic hydrolysis, and betulin from birch bark extracted by liquid CO2 containing ethanol. Inherent in these two extraction processes and production routes is the ability to show good environmental performance from a life cycle perspective. Extraction of high-value compounds also provides possibilities for innovation in the current agricultural, food and forest industry potentially leading to socio-economical benefits.

  • 284. Ekström, Jesper
    et al.
    Abrahamsson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Olson, Carol
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Kaynak, Filiz B.
    Eriksson, Lars
    Su, Licheng
    Becker, Hans-Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Åkermark, Björn
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Bio-inspired, side-on attachment of a ruthenium photosensitizer to an iron hydrogenase active site model2006In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 38, p. 4599-4606Article in journal (Refereed)
    Abstract [en]

    The first ruthenium - diiron complex [(mu- pdt) Fe-2(CO)(5){PPh2(C(6)H(4)CCbpy)} Ru(bpy)(2)](2+) 1 (pdt = propyldithiolate, bpy = 2,2'-bipyridine) is described in which the photoactive ruthenium trisbipyridyl unit is linked to a model of the iron hydrogenase active site by a ligand directly attached to one of the iron centers. Electrochemical and photophysical studies show that the light-induced MLCT excited state of the title complex is localized towards the potential diiron acceptor unit. However, the relatively mild potential required for the reduction of the acetylenic bipyridine together with the easily oxidized diiron portion leads to a reductive quenching of the excited state, instead. This process results in a transiently oxidized diiron unit which may explain the surprisingly high light sensitivity of complex 1.

  • 285. El Jastimi, R
    et al.
    Edwards, K
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Lafleur, M
    Characterization of permeability and morphological perturbations induced by nisin on phosphatidylcholine membranes.1999In: Biophys J, ISSN 0006-3495, Vol. 77, no 2, p. 842-52Article in journal (Refereed)
  • 286.
    Elfwing, A.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Surface Biotechnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    LeMarc, Y.
    Baranyi, J.
    Ballagi, A
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Surface Biotechnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Observing Growth and Division of Large Numbers of Individual Bacteria by Image Analysis2004In: Applied and Environmental Microbiology, Vol. 70, no 2, p. 675-678Article in journal (Refereed)
    Abstract [en]

    We describe a method that enabled us to observe large numbers of individual bacterial cells during a long period of cell growth and proliferation. We designed a flow chamber in which the cells attached to a transparent solid surface. The flow chamber was mounted on a microscope equipped with a digital camera. The shear force of the flow removed the daughter cells, making it possible to monitor the consecutive divisions of a single cell. In this way, kinetic parameters and their distributions, as well as some physiological characteristics of the bacteria, could be analyzed based on more than 1,000 single-cell observations. The method which we developed enabled us to study the history effect on the distribution of the lag times of single cells.

  • 287.
    Elhamili, Anisa
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Capillary electrophoresis of peptides and proteins using surface modified capillaries and enhancement of peak efficiencies2009Licentiate thesis, comprehensive summary (Other academic)
  • 288.
    Elhamili, Anisa
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Development of Capillary Electrophoresis Methods Coupled to Mass Spectrometry for Biomedical and Pharmaceutical Analysis2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The analysis of large intact proteins and complex biological samples containing drug molecules is a common complicated task for many scientists. However, due to the importance of these molecules, there is a growing interest in pharmaceutical and medicinal research to develop rapid, highly sensitive and efficient analytical techniques. The advantages of capillary electrophoresis (CE) in combination with mass spectrometry (MS) provide a powerful analytical tool. However, further improvement and development of these techniques are required to extend their utility and to meet the challenges of selected analytes. Thus, the scope of this thesis deals with the development of novel analytical methods to achieve efficient and high performance analysis of peptides, intact proteins, digests of complex samples and basic pharmaceutical drug compounds in biological matrices.

    Implementation of CE for routine analysis of proteins and complex samples is constrained by the partial adsorption to the capillary wall. Consequently, the use of surface modified capillaries is required to control the surface properties and prevent analyte adsorption. In this thesis, analyte adsorption was successfully prevented using tailored covalent cationic (M7C4I) and electrostatic cationic (PVPy-Me) coatings. Rapid and efficient separations of peptides, proteins and digests of complex samples such as cerebrospinal fluids were obtained with these coatings. The M7C4I coating showed a distinct ability to handle large intact proteins with a molecular size of over 0.5 MDa. The highest peak efficiencies and surprisingly high peak stacking effects were obtained by adding salts to the protein samples. The effect of salt additives on peak efficiencies of intact proteins was further demonstrated and compared using different surface modified capillaries. Additionally, rapid CE-ESI-MS quantification of pharmaceutical drug molecules in human plasma was performed after a SCX-SPE sample preparation method using the M7C4I coating. In conclusion, the results presented in this thesis show the strong potential of CE in combination with MS using electrospray ionization (ESI) for the analysis of peptides and large intact proteins and the applicability for clinical monitoring of the levels of pharmaceutical drug molecules in human plasma with high sensitivity and efficiency.

    List of papers
    1. Rapid capillary electrophoresis time-of-flight mass spectrometry separations of peptides and proteins using a monoquaternarized piperazine compound (M7C4l) for capillary coatings
    Open this publication in new window or tab >>Rapid capillary electrophoresis time-of-flight mass spectrometry separations of peptides and proteins using a monoquaternarized piperazine compound (M7C4l) for capillary coatings
    Show others...
    2008 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 29, no 8, p. 1619-1625Article in journal (Refereed) Published
    Abstract [en]

    A monoquaternarized piperazine, 1-(4-iodobutyl) 4-aza-1-azoniabicyclo[2,2,2] octane iodide (M7C4I), has been evaluated as a surface derivatization reagent for CE in combination with TOF MS for the analysis of proteins, peptides, and protein digests. The M7C4I piperazine, at alkaline pH, forms a covalent bond via alkylation of the ionized silanols producing a cationic surface with a highly stable and reversed EOF. The obtained surface yields rapid separations (less than 5 min) of peptides and proteins at acidic pH with high separation efficiencies (up to 1.1 X 10(6) plates/m for peptides and up to 1.8 x 10(6) plates/m for proteins) and no observed bleeding of the coating reagent into the mass spectrometer. The simplicity of the coating procedure also enables fast (2 min) regeneration of the surface, if necessary. This is useful in the analysis of complex samples in order to prevent possible memory effects. The potential of using M7C4I-coated capillaries for MS analysis of complex samples is demonstrated by the separation of peptides, proteins, and protein digests. Even more, the spectacular thing in which large intact proteins with molecular masses over 0.5 MDa could be separated. The coating showed good ability to handle these large proteins with high efficiency and retained peak shape as demonstrated by separation of IgG(1) (150 kDa) and thyroglobulin (669 kDa).

    Keywords
    Capillary electrophoresis, M7C4l, Peptides, Proteins, Protein digests, Time-of-flight
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-16217 (URN)10.1002/elps.200700737 (DOI)000255703100005 ()
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2017-12-08Bibliographically approved
    2. Analysis of peptides using N-methylpolyvinylpyridium as silica surface modifier for CE-ESI-MS
    Open this publication in new window or tab >>Analysis of peptides using N-methylpolyvinylpyridium as silica surface modifier for CE-ESI-MS
    Show others...
    2010 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 31, no 7, p. 1151-1156Article in journal (Refereed) Published
    Abstract [en]

    In this study, the N-methylpolyvinylpyridinuim polymer has for the first time been used as a silica surface modifier for CE in combination with ESI MS (CE-ESI-MS). The compatibility for ESI-MS was demonstrated by the analysis of peptides and protein digests. The N-methylpolyvinylpyridium surface interacts electrostatically with the ionized silanol groups, giving a cationic surface with a reversed EOF. The surface modifier gave rapid and repeatable separations of peptides, proteins and protein digests at acidic pH for more than 4 h of continuous use. The CE separation yielded peak efficiencies of up to 4.3 x 10(5) plates/m. The surface coating is highly compatible with ESI and facilitates the separation and analysis of complex peptide mixtures as shown by the analysis of BSA digests.

    Keywords
    CE, ESI, MS, N-methylpolyvinylpyridinuim, peptides
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-125809 (URN)10.1002/elps.200900536 (DOI)000276811000005 ()20209570 (PubMedID)
    Available from: 2010-05-28 Created: 2010-05-28 Last updated: 2017-12-12Bibliographically approved
    3. The effect of sample salt additives on capillary electrophoresis analysis of intact proteins using surface modified capillaries.
    Open this publication in new window or tab >>The effect of sample salt additives on capillary electrophoresis analysis of intact proteins using surface modified capillaries.
    Show others...
    2009 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 17, p. 3613-3620Article in journal (Refereed) Published
    Abstract [en]

    The effect of adding alkali salts to protein samples for capillary electrophoretic (CE) analysis of intact proteins was studied. A high degree of peak stacking, even for large proteins, was found to occur when alkali salts were added to the sample. The addition of salt to the protein sample promotes a strong improvement in the peak efficiency of individual proteins giving up to 2.1 x 10(6) apparent plates/m. The concentration of salt required in the sample to reach optimal peak efficiency show dependency on both the molecular weight and molar concentration of the protein. However, adding salt will, at a sufficiently high concentration, cause a mixture of proteins to co-migrate to one very sharp peak. The observed sample stacking effect was obtained with a number of different surface modified silica capillaries indicating a general phenomenon and not surface coating specific.

    Keywords
    Capillary electrophoresis, alkali salt, intact protein analysis, coated capillary, stacking effect
    National Category
    Chemical Sciences
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-100628 (URN)10.1016/j.chroma.2008.12.037 (DOI)000265467200004 ()19150070 (PubMedID)
    Available from: 2009-04-03 Created: 2009-04-03 Last updated: 2017-12-13Bibliographically approved
    4. Optimizing the extraction, separation and quantification of tricyclic antidepressant drugs in human plasma with CE-ESI-TOF-MS using cationic coated capillaries
    Open this publication in new window or tab >>Optimizing the extraction, separation and quantification of tricyclic antidepressant drugs in human plasma with CE-ESI-TOF-MS using cationic coated capillaries
    2011 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 32, no 6-7, p. 647-658Article in journal (Refereed) Published
    Abstract [en]

    In this study, the extraction and CE-ESI-TOF-MS analysis of tricyclic antidepressant (TCA) drugs imipramine, desipramine, clomipramine and norclomipramine in human plasma has been optimized. The CE capillaries were modified with ω-iodo-alkyl ammonium salt (M7C4I coating) to reduce analyte adsorption to the silica wall. The use of a strong cation exchange (SCX) solid-phase extraction (SPE) column specifically designed for the extraction of basic drug species from biofluids gave very clean extracts with high and reproducible recoveries. The extraction recoveries were ranging between 87 and 91% with % RSD values of 0.5-1.7% (n=3). The obtained strong cation exchange-SPE extracts of the TCA in human plasma only contained the analytes of interest. The optimized CE separation conditions were obtained by adding ACN and acetic acid to the sample while using an aqueous BGE. The CE-ESI-TOF-MS analysis was performed within 6min for all TCA analytes under the optimized condition with peak efficiencies up to 1.4×105plates/m and an average % RSD of the migration times of the analytes of 0.3% (n=5). The presented method can readily be used for the extraction and quantification of basic drug species in human biological fluids and in pharmaceutical formulations.

    Keywords
    Capillary electrophoresis, Mass spectrometry, Tricyclic Antidepressant Drugs, Quantification, Human plasma
    National Category
    Other Basic Medicine
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-143784 (URN)10.1002/elps.201000566 (DOI)000288602000001 ()21341290 (PubMedID)
    Available from: 2011-01-25 Created: 2011-01-25 Last updated: 2018-01-12Bibliographically approved
    5. A method for quantitative analysis of an anticancer drug in human plasma with CE-ESI-TOF-MS
    Open this publication in new window or tab >>A method for quantitative analysis of an anticancer drug in human plasma with CE-ESI-TOF-MS
    2011 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 32, no 13, p. 1778-1785Article in journal (Refereed) Published
    Abstract [en]

    In this study, the extraction recoveries of an anticancer drug (Imatinib) from human plasma using a common liquid-liquid extraction (LLE) method and a new strong cation exchange (SCX) solid-phase extraction (SPE) column was investigated. The extracts were analyzed with CE coupled on-line to electrospray ionization (ESI) time-of-flight mass spectrometry (TOF-MS) using a monoquaternarized piperazine compound (M7C4I) for capillary coatings. Clean extracts with high and reproducible extraction recoveries ranging between 85 and 91% with % RSD values of 2.5% (n = 3) were obtained using the SCX-SPE columns. This can be compared with the recoveries obtained with the LLE method ranging between 30 and 35%. The CE-ESI-TOF-MS analysis was performed in = 0.997 and % RSD values of 0.5% (n = 3). The intra-day and inter-day assay variations were lower than 8%. The presented CE-ESI-TOF-MS method with the use of SCX-SPE columns yielded rapid, efficient and high extraction recoveries together with high sensitivity (LOD 5 ng/mL), selectivity and good linearity. Accordingly, the method can readily be used for accurate determination and therapeutic monitoring of the Imatinib blood levels for more effective patient treatment. In addition, it can be applied for the extraction, quantification and clinical assessments of metabolites of Imatinib and other basic pharmaceutical drug molecules in biological fluids or pharmaceutical dosage forms.

    Keywords
    Capillary electrophoresis, Human plasma, Imatinib, Mass spectrometry, Quantification, Theraputic drug monitoring.
    National Category
    Other Basic Medicine
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-143791 (URN)10.1002/elps.201100121 (DOI)000292971000027 ()
    Available from: 2011-01-25 Created: 2011-01-25 Last updated: 2018-01-12Bibliographically approved
  • 289.
    Elhamili, Anisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    A method for quantitative analysis of an anticancer drug in human plasma with CE-ESI-TOF-MS2011In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 32, no 13, p. 1778-1785Article in journal (Refereed)
    Abstract [en]

    In this study, the extraction recoveries of an anticancer drug (Imatinib) from human plasma using a common liquid-liquid extraction (LLE) method and a new strong cation exchange (SCX) solid-phase extraction (SPE) column was investigated. The extracts were analyzed with CE coupled on-line to electrospray ionization (ESI) time-of-flight mass spectrometry (TOF-MS) using a monoquaternarized piperazine compound (M7C4I) for capillary coatings. Clean extracts with high and reproducible extraction recoveries ranging between 85 and 91% with % RSD values of 2.5% (n = 3) were obtained using the SCX-SPE columns. This can be compared with the recoveries obtained with the LLE method ranging between 30 and 35%. The CE-ESI-TOF-MS analysis was performed in = 0.997 and % RSD values of 0.5% (n = 3). The intra-day and inter-day assay variations were lower than 8%. The presented CE-ESI-TOF-MS method with the use of SCX-SPE columns yielded rapid, efficient and high extraction recoveries together with high sensitivity (LOD 5 ng/mL), selectivity and good linearity. Accordingly, the method can readily be used for accurate determination and therapeutic monitoring of the Imatinib blood levels for more effective patient treatment. In addition, it can be applied for the extraction, quantification and clinical assessments of metabolites of Imatinib and other basic pharmaceutical drug molecules in biological fluids or pharmaceutical dosage forms.

  • 290.
    Elhamili, Anisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Samuelsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Wetterhall, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Optimizing the extraction, separation and quantification of tricyclic antidepressant drugs in human plasma with CE-ESI-TOF-MS using cationic coated capillaries2011In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 32, no 6-7, p. 647-658Article in journal (Refereed)
    Abstract [en]

    In this study, the extraction and CE-ESI-TOF-MS analysis of tricyclic antidepressant (TCA) drugs imipramine, desipramine, clomipramine and norclomipramine in human plasma has been optimized. The CE capillaries were modified with ω-iodo-alkyl ammonium salt (M7C4I coating) to reduce analyte adsorption to the silica wall. The use of a strong cation exchange (SCX) solid-phase extraction (SPE) column specifically designed for the extraction of basic drug species from biofluids gave very clean extracts with high and reproducible recoveries. The extraction recoveries were ranging between 87 and 91% with % RSD values of 0.5-1.7% (n=3). The obtained strong cation exchange-SPE extracts of the TCA in human plasma only contained the analytes of interest. The optimized CE separation conditions were obtained by adding ACN and acetic acid to the sample while using an aqueous BGE. The CE-ESI-TOF-MS analysis was performed within 6min for all TCA analytes under the optimized condition with peak efficiencies up to 1.4×105plates/m and an average % RSD of the migration times of the analytes of 0.3% (n=5). The presented method can readily be used for the extraction and quantification of basic drug species in human biological fluids and in pharmaceutical formulations.

  • 291.
    Elhamili, Anisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Wetterhall, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Arvidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Sebastiano, Roberto
    Righetti, Pier Giorgio
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Rapid capillary electrophoresis time-of-flight mass spectrometry separations of peptides and proteins using a monoquaternarized piperazine compound (M7C4l) for capillary coatings2008In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 29, no 8, p. 1619-1625Article in journal (Refereed)
    Abstract [en]

    A monoquaternarized piperazine, 1-(4-iodobutyl) 4-aza-1-azoniabicyclo[2,2,2] octane iodide (M7C4I), has been evaluated as a surface derivatization reagent for CE in combination with TOF MS for the analysis of proteins, peptides, and protein digests. The M7C4I piperazine, at alkaline pH, forms a covalent bond via alkylation of the ionized silanols producing a cationic surface with a highly stable and reversed EOF. The obtained surface yields rapid separations (less than 5 min) of peptides and proteins at acidic pH with high separation efficiencies (up to 1.1 X 10(6) plates/m for peptides and up to 1.8 x 10(6) plates/m for proteins) and no observed bleeding of the coating reagent into the mass spectrometer. The simplicity of the coating procedure also enables fast (2 min) regeneration of the surface, if necessary. This is useful in the analysis of complex samples in order to prevent possible memory effects. The potential of using M7C4I-coated capillaries for MS analysis of complex samples is demonstrated by the separation of peptides, proteins, and protein digests. Even more, the spectacular thing in which large intact proteins with molecular masses over 0.5 MDa could be separated. The coating showed good ability to handle these large proteins with high efficiency and retained peak shape as demonstrated by separation of IgG(1) (150 kDa) and thyroglobulin (669 kDa).

  • 292.
    Elhamili, Anisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Wetterhall, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Puerta, Angel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Westerlund, Douglas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    The effect of sample salt additives on capillary electrophoresis analysis of intact proteins using surface modified capillaries.2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 17, p. 3613-3620Article in journal (Refereed)
    Abstract [en]

    The effect of adding alkali salts to protein samples for capillary electrophoretic (CE) analysis of intact proteins was studied. A high degree of peak stacking, even for large proteins, was found to occur when alkali salts were added to the sample. The addition of salt to the protein sample promotes a strong improvement in the peak efficiency of individual proteins giving up to 2.1 x 10(6) apparent plates/m. The concentration of salt required in the sample to reach optimal peak efficiency show dependency on both the molecular weight and molar concentration of the protein. However, adding salt will, at a sufficiently high concentration, cause a mixture of proteins to co-migrate to one very sharp peak. The observed sample stacking effect was obtained with a number of different surface modified silica capillaries indicating a general phenomenon and not surface coating specific.

  • 293.
    Elhamili, Anisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Wetterhall, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Sjödin, Marcus O.D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Sebastiano, Roberto
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Analysis of peptides using N-methylpolyvinylpyridium as silica surface modifier for CE-ESI-MS2010In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 31, no 7, p. 1151-1156Article in journal (Refereed)
    Abstract [en]

    In this study, the N-methylpolyvinylpyridinuim polymer has for the first time been used as a silica surface modifier for CE in combination with ESI MS (CE-ESI-MS). The compatibility for ESI-MS was demonstrated by the analysis of peptides and protein digests. The N-methylpolyvinylpyridium surface interacts electrostatically with the ionized silanol groups, giving a cationic surface with a reversed EOF. The surface modifier gave rapid and repeatable separations of peptides, proteins and protein digests at acidic pH for more than 4 h of continuous use. The CE separation yielded peak efficiencies of up to 4.3 x 10(5) plates/m. The surface coating is highly compatible with ESI and facilitates the separation and analysis of complex peptide mixtures as shown by the analysis of BSA digests.

  • 294.
    Elmgren, Maja
    Uppsala University, University Administration. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Att gå från ord till handling: Bologna som språngbräda för pedagogisk utveckling genom samverkan med pedagogiska ledare2007Conference paper (Refereed)
  • 295.
    Elmgren, Maja
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Förebilder och auktoriteter2009In: Den beprövade erfarenheten: pedagogiska utvecklare : ett yrksekunnande i vardande. / [ed] El Gaidi, Khalid & Högfeldt, Anna-Karin, Stockholm: KTH, Learning lab , 2009, p. 20-25Chapter in book (Other (popular science, discussion, etc.))
  • 296.
    Elmgren, Maja
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Erhardsson, Margareta
    Apelgren, Karin
    Winka, Katarina