Change search
Refine search result
123 1 - 50 of 103
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Agaton, Charlotta
    et al.
    KTH, Superseded Departments, Biotechnology.
    Uhlén, Mathias
    KTH, Superseded Departments, Biotechnology.
    Hober, Sophia
    KTH, Superseded Departments, Biotechnology.
    Genome-based proteomics2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 9, p. 1280-1288Article in journal (Refereed)
    Abstract [en]

    Protein-protein interactions play crucial roles in various biological pathways and functions. Therefore, the characterization of protein levels and also the network of interactions within an organism would contribute considerably to the understanding of life. The availability of the human genome sequence has created a range of new possibilities for biomedical research. A crucial challenge is to utilize the genetic information for better understanding of protein distribution and function in normal as well as in pathological biological processes. In this review, we have focused on different platforms used for systematic genome-based proteome analyses. These technologies are in many ways complementary and should be seen as various ways to elucidate different functions of the proteome.

  • 2.
    Aldaeus, Fredrik
    et al.
    KTH.
    Lin, Yuan
    KTH.
    Roeraade, Johan
    KTH.
    Amberg, Gustav
    KTH.
    Superpositioned dielectrophoresis for enhanced trapping efficiency2005In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 26, no 22, p. 4252-4259Article in journal (Refereed)
    Abstract [en]

    One of the major applications for dielectrophoresis is selective trapping and fractionation of particles. If the surrounding medium is of low conductivity, the trapping force is high, but if the conductivity increases, the attraction decreases and may even become negative. However, high-conductivity media are essential when working with biological material such as living cells. In this paper, some basic calculations have been performed, and a model has been developed which employs both positive and negative dielectrophoresis in a channel with interdigitated electrodes. The finite element method was utilized to predict the trajectories of Escherichia coli bacteria in the superpositioned electrical fields. It is shown that a drastic improvement of trapping efficiency can be obtained in this way, when a high conductivity medium is employed.

  • 3.
    Aldaeus, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Lin, Yuan
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Roeraade, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Superpositioned dielectrophoresis for enhanced trapping efficiency2005In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 26, no 22, p. 4252-4259Article in journal (Refereed)
    Abstract [en]

    One of the major applications for dielectrophoresis is selective trapping and fractionation of particles. If the surrounding medium is of low conductivity, the trapping force is high, but if the conductivity increases, the attraction decreases and may even become negative. However, high-conductivity media are essential when working with biological material such as living cells. In this paper, some basic calculations have been performed, and a model has been developed which employs both positive and negative dielectrophoresis in a channel with interdigitated electrodes. The finite element method was utilized to predict the trajectories of Escherichia coli bacteria in the superpositioned electrical fields. It is shown that a drastic improvement of trapping efficiency can be obtained in this way, when a high conductivity medium is employed.

  • 4.
    Amini, Ahmad
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Double-injection capillary electrophoresis for the identification of analytes2014In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 35, no 20, p. 2915-2921Article in journal (Refereed)
    Abstract [en]

    This paper presents a new approach for identifying analytes by CE. The compound to be identified is analyzed together with the corresponding reference standard during a double injection capillary electrophoretic run. The inter-plug distance is regulated by applying an electrical field over the capillary for a predetermined time period (tPE). The migration time of an analyte being exposed to the partial electrophoresis was calculated from the partial migration time (tmig(p)) as described in this paper. The identification is based on the closeness of agreement between the calculated migration time (tmig(c)) and observed migration time (tmig) of the reference standard. The validity of the derived equations was checked by analyzing several substances such as caffeine, melamine, acetyl salicylic acid, paracetamol, ibuprofen, metoprolol, naproxen, somatropin, several insulin analogs, as well as different pharmaceutical and natural products. The migration time ratios for the identified solutes varied between 0.996 and 1.006 (i.e., 1.001 ± 0.005), indicating good agreement between the observed and calculated migration times.

  • 5.
    Amini, Ahmad
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Lodén, Henrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Pettersson, Curt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Arvidsson, Torbjörn
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Principles for different modes of multiple-injection CZE2008In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 29, no 19, p. 3952-3958Article in journal (Refereed)
    Abstract [en]

    This paper introduces four different modes of multiple-injection CZE (MICZE). The validity of these MICZE models was evaluated by the experimental data. Prior to the application of MICZE, the electrophoretic conditions are developed in the single-injection mode by adjusting different experimental parameters such as pH, type and concentration of buffer additives and temperature. Based on the migration time difference (tmig) between the analyte and the internal standard or injection marker, one or more MICZE modes can be employed. The injection marker is added to the sample to compensate for injection-volume fluctuations. The inter-plug distance is regulated by applying an electrical field over the capillary for a short period of time between each injection. After the final injection, the separation is completed by electrophoresis for a time period corresponding to that in the single-injection mode

  • 6.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Jonsson, C.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Patterned self-assembled beads in silicon channels2001In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 22, no 18, p. 3876-3882Article in journal (Refereed)
    Abstract [en]

    A novel technique enabling selective bead trapping in microfluidic devices without the use of physical barriers is presented in this paper. It is a fast, convenient and simple method, involving microcontact printing and self-assembly, that can be applied to silicon, quartz or plastic substrates. In the first step, channels are etched in the substrate. The surface chemistry of the internal walls of the channels is then modified by microcontact printing. The chip is submerged in a bead slurry where beads self-assemble based on surface chemistry and immobilize on the internal walls of the channels. Silicon channels (100 mum wide and 50 mum deep) have been covered with monolayers of streptavidin-, amino- and hydroxy-functionalized microspheres and resulted in good surface coverage of beads on the channel walls. A high-resolution pattern of lines of self-assembled streptavidin beads, as narrow as 5 mum, has also been generated on the bottom of a 500 mum wide and 50 mum deep channel. Flow tests were performed in sealed channels with the different immobilized beads to confirm that the immobilized beads could withstand the forces generated by water flowing in the channels. The presented results indicate that single beads can be precisely positioned within microfluidic devices based on self-assembly which is useful as screening and analysis tools within the field of biochemistry and organic chemistry.

  • 7.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    van der Wijngaart, Wouter
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Micromachined filter-chamber array with passive valves for biochemical assays on beads2001In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 22, no 2, p. 249-257Article in journal (Refereed)
    Abstract [en]

    The filter-chamber array presented here enables a real-time parallel analysis of three different samples on beads in a volume of 3 nL, on a 1 cm(2) chip. The filter-chamber array is a system containing three filter-chambers, three passive valves at the inlet channels and a common outlet. The design enables parallel sample handling and time-controlled analysis. The device is microfabricated in silicon and sealed with a Pyrex lid to enable real-time analysis. Single nucleotide polymorphism analysis by using pyrose-quencing has successfully been performed in single filter-chamber devices. The passive valves consist of plasma-deposited octafluorocyclobutane and show a much higher resistance towards water and surface-active solutions than previous hydrophobic patches. The device is not sensitive to gas bubbles, clogging is rare and reversible, and the filter-chamber array is reusable. More complex (bio)chemical reactions on beads can be performed in the devices with passive valves than in the devices without valves.

  • 8.
    Axén, Jakob
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Axelsson, Bengt-Olof
    Jörntén-Karlsson, Magnus
    Petersson, Patrik
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    An investigation of peak-broadening effects arising when combining CE with MS.2007In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 28, no 18, p. 3207-3213Article in journal (Refereed)
    Abstract [en]

    In this study, peak-broadening effects caused by nebulizing gas flow and lack of temperature control have been investigated for separation capillaries with three different inner diameters. The study was performed with serial UV/ESI-MS detection in an effort to distinguish between peak broadening arising in the separation and peak broadening arising in the ion source. The nebulizing gas was found to significantly affect both migration time and separation efficiency when using capillaries with 50 and 75 µm id. If the nebulizing gas is on during injection, the injection volume increases to such an extent that significant peak broadening is induced. Reducing the id to 25 µm minimizes the parabolic flow induced by the nebulizing gas. Results indicate that the nebulizing gas pressure can be optimized to minimize peak broadening in the ion source. A decrease in detection sensitivity, possibly related to the orthogonal design of the interface, was observed when the nebulizing gas pressure was increased. A tapered capillary tip was found to provide superior separation efficiency as well as sensitivity.

  • 9. Bacskay, Ivett
    et al.
    Takatsy, Aniko
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry.
    Vegvari, Akos
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry.
    Elfwing, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology, Centre for Surface Biotechnology.
    Balllagi-Pordany, Andras
    Kilar, Ferenc
    Hjertén, Stellan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry.
    Universal method for synthesis of artificial gel antibodies by the imprinting approach combined with a unique electrophoresis technique for detection of minute structural differences of proteins, viruses, and cells (bacteria). III: Gel antibodies against cells (bacteria)2006In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 27, no 23, p. 4682-4687Article in journal (Refereed)
    Abstract [en]

    Artificial antibodies in the form of gel granules were synthesized from the monomers acrylamide and N,N'-methylenebisacrylamide by the imprinting method in the presence of Echerichia coli bacteria as template. The electrophoretic migration velocities of the gel antibodies (i) saturated with the antigen (Escherichia coli MRE-600), (ii) freed of the antigen, and (iii) resaturated with bacteria, were determinated by electrophoresis in a rotating narrow-bore tube of 245 mm length and the 2.5 and 9.6 mm inner and outer diameters, respectively. Removal of bacteria from the gel antibodies was made by treatment with enzymes, followed by washing with SDS and buffer. Gel granules becoming charged by adsorption of bacteria move in an electrical field. We obtained a significant selectivity of gel antibodies for E coli MRE-600, since the granules did not interact with Lactococcus lactis; and when E coli BL21 bacteria were added to the gels selective for E coli MRE-600, a significant difference in the migration rate of the complexes formed with the two strains was observed indicating the ability of differentiation between the two strains. The gel antibodies can be used repeatedly. The new imprinting method for the synthesis of artificial gel antibodies against bioparticles described herein, and the classical electrophoretic analysis technique employed, thus represent - when combined - a new approach to distinguish between different types and strains of bacteria. The application area can certainly be extended to cover other classes of cells.

  • 10.
    Bergquist, Jonas
    et al.
    Department of Psychiatry and Neurochemistry, Göteborg University, Sahlgrenska University Hospital.
    Josefsson, E
    Division of Reproductive and Perinatal Health Care, Karolinska Institutet.
    Tarkowski, A
    Department of Rheumatology and Inflammation Research, University of Gothenburg.
    Ekman, R
    Department of Psychiatry and Neurochemistry, Göteborg University, Sahlgrenska University Hospital.
    Ewing, A
    Chemistry, Pennsylvania State University.
    Measurements of catecholamine-mediated apoptosis of immunocompetent cells by capillary electrophoresis.1997In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 18, no 10, p. 1760-6Article in journal (Refereed)
    Abstract [en]

    Single cell analysis with capillary electrophoresis, a technique capable of detecting zeptomole quantities (10(-21) mole) of neurochemical species, has been used to demonstrate that lymphocytes are capable of active synthesis of dopamine and norepinephrine. Exposure of lymphocytes to catecholamines at concentrations as low as 10 nM leads to decreased proliferation and differentiation, e.g. interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and immunoglobulin (Ig). In addition, both inhibition of dopamine uptake with nomifensine and inhibition of packing of catecholamines into vesicles with tetrabenazine, results in significantly lower levels of dopamine and norepinephrine (p < 0.01 and p < 0.05, respectively). The catecholamine-dependent inhibition of T- and B-lymphocyte activity is mediated via an induction of a Bcl-2/Bax and Fas/FasL involved apoptosis. These findings indicate a novel mechanism for regulation of lymphocyte activity in the central nervous system, whereby elevated regional levels of catecholamines might lead to the immunoprivilege of the brain.

  • 11.
    Bohlin, Maria E
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Blomberg, Lars G.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Heegaard, Niels H H
    Statens Serum Institut, Copenhagen.
    Effects of ionic strength, temperature and conformation on affinity interactions of β2-glycoprotein I monitored by capillary electrophoresis2011In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 32, p. 728-737Article in journal (Refereed)
    Abstract [en]

    We have used CE to evaluate the interaction between β2-glycoprotein I (β2gpI) and heparin. β2gpI is a human plasma protein involved in the blood coagulation cascade. It is of interest to functionally characterize the interactions of β2gpI because the exact function is not entirely known and because circulating autoantibodies against β2gpI are associated with an increased risk of thrombotic events.

     

    The effect of the ionic strength, temperature, and conformation of the protein on the interaction between β2gpI and heparin has been studied. The CE procedure for this study is simple, fast and automatic. β2gpI and heparin were allowed to interact during electrophoresis at different ionic strength buffers and at different capillary temperatures. To mimic perturbation of the conformation of β2gpI, different denaturing agents (SDS, ACN and urea) were added to the background electrolyte. While simple 1:1 binding isotherms were obtained at 22 °C the data strongly suggests that at physiological temperature the binding stoichiometry is not 1:1 and/or that cooperative interactions begin to play a role. We found that (i) the KD values differed by a factor of 60 at the ionic strengths studied (ii) β2gpI was resistant to denaturation with SDS and ACN, but was partially denatured by urea and (iii) the KD for the β2gpI-heparin interaction in the presence of urea was 10 times higher than the KD determined at the same conditions without urea added. Therefore, we conclude that the interaction between β2gpI and heparin is dependent on electrostatic interactions and on the conformation of β2gpI. 

  • 12.
    Bohlin, Maria E.
    et al.
    Karlstad University, Division for Chemistry.
    Blomberg, Lars G.
    Karlstad University, Division for Chemistry.
    Heegard, Niels H.H.
    Department of Autoimmunology, Statens Serum Institut, Copenhagen.
    Utilizing the pH hysteresis effect for versatile and simple electrophoretic analysis of protein in bare fused-silica capillaries2005In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 26, no 21, p. 4043-4049Article in journal (Refereed)
  • 13.
    Bohlin, Maria
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Johannesson, Ida
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Carlsson, Gunilla
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Heegaard, Nils H H
    Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Estimation of the amount of β2-glycoprotein I adsorbed at the inner surface of fused silica capillaries after acidic, neutral and alkaline pretreatment2012In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 33, no 12, p. 1695-1702Article in journal (Refereed)
    Abstract [en]

    Sample adsorption to the inner surface of fused silica capillaries is a common problem in

    CE when analyzingmacromolecules and is harmful to the analysis. We previously utilized

    the pH hysteresis effect of fused silica to facilitate electrophoresis of the strongly adsorbing

    protein β2gpI in plain-fused silica capillaries at neutral pH. In the present paper, the

    effect of different pretreatments of the capillary on the adsorption of the β2-glycoprotein

    I has been investigated using electroosmosis markers, SDS mobilization, and imaging

    based on indirect immunofluorescence microscopy for direct visualization. The amount

    of β2gpI adsorbed on the surface was probed using all these independent techniques after

    electrophoresis at neutral pH on capillaries pretreated with HCl, background electrolyte

    (BGE), and NaOH. BGE pretreatment was included as a positive control. We found that

    80% or more of the starting material was adsorbed to the inner surface of the silica

    capillaries during electrophoresis after pretreatment with only BGE or with NaOH, but

    after acidic pretreatment the loss was consistently less than 20%. NaOH most efficiently

    removes adsorbed protein between runs. A theoretical calculation of the pH change of

    the BGE showed that electrolysis affects the pH more than the deprotonation of silanols

    during electrophoresis. We conclude that acidic pretreatment of fused silica capillaries

    diminishes adsorption of β2gpI by decreasing charge-dependent wall adsorption.

     

  • 14.
    Boija, Elisabet
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Lundquist, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Nilsson, Mikael
    Department of Chemistry and Biomedical Sciences, University of Kalmar, Kalmar, Sweden.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Isaksson, Roland
    Department of Chemistry and Biomedical Sciences, University of Kalmar, Kalmar, Sweden.
    Johansson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Bilayer disk capillary electrophoresis: a novel method to study drug partitioning into membranes2008In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 29, no 16, p. 3377-3383Article in journal (Refereed)
    Abstract [en]

    CE in the presence of lipid bilayer disks was introduced as a new approach in membrane partitioning studies. The disks were used as a pseudostationary phase in the partial-filling mode of CE and the partitioning of cationic drugs was determined. The migration times of the analytes increased linearly with the lipid amount in the system. An appropriate algorithm for the calculation of a partition coefficient is presented. In the disk-shaped bilayers, which have excellent stability and shelf life, all of the lipids are readily available for interaction and the disks can be used as realistic cell membrane models.

  • 15.
    Bossi, A
    et al.
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Castelletti, L
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Piletsky, SA
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Turner, APF
    Cranfield University, UK.
    Righetti, PG
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Towards the development of an integrated capillary electrophoresis optical biosensor2003In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 24, no 19-20, p. 3356-3363Article in journal (Refereed)
    Abstract [en]

    Extending the previous preliminary study on the construction of a capillary electrophoresis (CE)/sensor for the detection of reducing analytes, we focus the interest on the simultaneous detection of redox active species, which are important indicators of the oxidative damage in tissues, of food preservation, and of pollution. The CE/sensor was built by modifying the detector-portion of the capillary with the redox-sensitive polymer polyaniline (PANI). The analyte is detected by monitoring the changes in optical absorption of the PANI film. The CE/sensor was tested, with good results, with ascorbic acid, glutathione (GSH), as well as with compounds with very close similarity (ascorbic and isoascorbic acid). The kinetics of oxidation and reduction of PANI were evaluated. Further a PANI/CE-biological sensor was developed by coupling an enzyme, glucose oxidase (GOD), to the PANI-modified portion of the capillary. The stability of the immobilized GOD and the sensitivity of the CE/biosensor were studied, by using glucose as test analyte in concentrations within the physiological range. The results indicate that the CE/biosensor had good stability (more than 75% of original activity retained after 30 operational days), manufacturing reproducibility and a sensing range convenient for monitoring physiological glucose (1-24 mm).

  • 16.
    Bossi, A
    et al.
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Piletsky, SA
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Turner, APF
    Cranfield University, UK.
    Righetti, PG
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Repartition effect of aromatic polyaniline coatings on the separation of bioactive peptides in capillary electrophoresis2002In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 23, no 2, p. 203-208Article in journal (Refereed)
    Abstract [en]

    The capillary walls of fused-silica capillary electrophoresis (CE) columns were modified with a thin film of polyaniline (PANI), providing open-tubular columns with a stable coating containing aromatic groups and amine functionalities. Fast and efficient separations were observed for small bioactive peptides under acidic conditions on PANI-coated columns. The mechanism of separation is based on hydrophobic interactions between the analytes and the polymeric matrix. Good reproducibility was observed from run-to-run. Due to the simple derivatization procedure, method flexibility, the uniformity of the coating and its stability, conjugated polymers could find practical application in capillary zone electrophoresis (CZE) separations.

  • 17.
    Bus, Magdalena M.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medicinsk genetik och genomik.
    Karas, Ognjen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medicinsk genetik och genomik.
    Allen, Marie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medicinsk genetik och genomik.
    Multiplex pyrosequencing of InDel markers for forensic DNA analysis2016In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 37, no 23-24, p. 3039-3045Article in journal (Refereed)
    Abstract [en]

    The capillary electrophoresis (CE) technology is commonly used for fragment length separation of markers in forensic DNA analysis. In this study, pyrosequencing technology was used as an alternative and rapid tool for the analysis of biallelic InDel (insertion/deletion) markers for individual identification. The DNA typing is based on a subset of the InDel markers that are included in the Investigator (R) DIPplex Kit, which are sequenced in a multiplex pyrosequencing analysis. To facilitate the analysis of degraded DNA, the polymerase chain reaction (PCR) fragments were kept short in the primer design. Samples from individuals of Swedish origin were genotyped using the pyrosequencing strategy and analysis of the Investigator (R) DIPplex markers with CE. A comparison between the pyrosequencing and CE data revealed concordant results demonstrating a robust and correct genotyping by pyrosequencing. Using optimal marker combination and a directed dispensation strategy, five markers could be multiplexed and analyzed simultaneously. In this proof-of-principle study, we demonstrate that multiplex InDel pyrosequencing analysis is possible. However, further studies on degraded samples, lower DNA quantities, and mixtures will be required to fully optimize InDel analysis by pyrosequencing for forensic applications. Overall, although CE analysis is implemented in most forensic laboratories, multiplex InDel pyrosequencing offers a cost-effective alternative for some applications.

  • 18.
    Castelletti, L
    et al.
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Piletsky, SA
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Turner, APF
    Cranfield University, UK.
    Righetti, PG
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Bossi, A
    University Verona, Department Science and Technology, I-37134 Verona, Italy; Cranfield University, Institute Biosci and Technology, Silsoe, Beds, England; .
    Development of an integrated capillary electrophoresis/sensor for L-ascorbic acid detection2002In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 23, no 2, p. 209-214Article in journal (Refereed)
    Abstract [en]

    A CE/biosensor for measuring ascorbic acid was developed by coupling a polyaniline optical sensor and capillary electrophoresis (CE). The capillary column was partially modified with a thin film of polyaniline redox sensitive material. Ascorbic acid was detected by monitoring the changes in optical absorbance occurring to the polyaniline film upon the reduction reaction. The sensor response (change in optical absorbance at 650 nm) is proportional to the concentration of ascorbic acid over a range of 2.5-250 mg/L and the response range has shown a clear dependence on the characteristics of the polymerized film. High specificity and sensitivity of the present method, low sample consumption, short times of response (ca. 2 min) and the reproducibility of the results demonstrate that the CE/polyaniline-sensor could be further employed in the study of the relation between the content of L-ascorbic acid in body fluids and clinical parameters, e.g., cell ageing.

  • 19. Curcio, M.
    et al.
    Stalhandske, P.
    Lindberg, P.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Multiplex high-throughput solid-phase minisequencing by capillary electrophoresis and liquid core waveguide fluorescence detection2002In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 23, no 10, p. 1467-1472Article in journal (Refereed)
    Abstract [en]

    Minisequencing, solid-phase single-nucleotide primer extension reaction, is a robust method for performing multiplex single-nucleotide polymorphism (SNP) analysis. We have combined this technology with capillary gel electrophoresis in a multicapillary format, using liquid core waveguide (LCW) fluorescence detection. Polymerase chain reaction (PCR) amplification of multiple DNA targets is performed with one primer for each target biotinylated. Separation of the complementary strands, minisequencing and washing steps are carried out using streptavidin-coated magnetic beads. Dideoxynucleotides analogues labelled with different fluorophores are used for the extension of the minisequencing primers. The extended oligonucleotides, the length of which defines the position on the target and the color the identity of the polymorphism, are then separated in a gel-filled array of capillaries, coated on the outside with a layer of a fluoropolymer to provide the liquid core waveguide characteristics. The technology has a potential for extremely high throughputs when a combination of multiplex PCR-minisequencing is used together with a large array of capillaries, four-color detection and high-speed separation.

  • 20.
    Drabek, Jiri
    et al.
    Palacky Univ, Fac Med & Dent, Inst Mol & Translat Med, Hnevotinska 5, Olomouc 77900, Czech Republic..
    Smolikova, Michaela
    Palacky Univ, Dept Biochem, Olomouc, Czech Republic..
    Kalendar, Ruslan
    Univ Helsinki, LUKE BI Plant Genome Dynam, Inst Biotechnol, Helsinki, Finland.;Minist Educ & Sci Republ Kazakhstan, Sci Comm, RSE Natl Ctr Biotechnol, Astana, Kazakhstan..
    Lopes Pinto, Fernando A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Pavlousek, Pavel
    Mendel Univ Brno, Dept Viticulture & Enol, Brno, Czech Republic..
    KleparnIk, Karel
    ASCR, Inst Analyt Chem, Brno, Czech Republic..
    Frebort, Ivo
    Palacky Univ, Fac Sci, Ctr Reg Hana Biotechnol & Agr Res, Olomouc, Czech Republic..
    Design and validation of an STR hexaplex assay for DNA profiling of grapevine cultivars2016In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 37, no 23-24, p. 3059-3067Article in journal (Refereed)
    Abstract [en]

    Although the analysis of length polymorphism at STR loci has become a method of choice for grape cultivar identification, the standardization of methods for this purpose lags behind that of methods for DNA profiling in human and animal forensic genetics. The aim of this study was thus to design and validate a grapevine STR protocol with a practically useful level of multiplexing. Using free bioinformatics tools, published primer sequences, and nucleotide databases, we constructed and optimized a primer set for the simultaneous analysis of six STR loci (VVIi51, scu08vv, scu05vv, VVMD17, VrZAG47, and VrZAG83) by multiplex PCR and CE with laser-induced fluorescence, and tested it on 90 grape cultivars. The new protocol requires subnanogram quantities of the DNA template and enables automated, high-throughput genetic analysis with reasonable discriminatory power. As such, it represents a step toward further standardization of grape DNA profiling.

  • 21. Dzieciatkowska, Monika
    et al.
    Schweda, Elke K. H.
    Södertörn University, School of Life Sciences.
    Moxon, E. Richard
    Richards, James C.
    Li, Jianjun
    Characterization of intact lipopolysaccharides from the Haemophilus influenzae strain RM 118 using electrophoresis-assisted open-tubular liquid chromatography-mass spectrometry2008In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 29, no 10, p. 2171-2181Article in journal (Refereed)
    Abstract [en]

    We have applied an electrophoresis-assisted open-tubular LC-MS method for analyzing intact lipopolysaccharides (LPSs) from Haemophilus influenzae strain RM 118 (Rd). We were able to obtain structural information on both core oligosaccharides (OSs) and the lipid A moiety including the sialylation, glycylation, and the distribution of fatty acid residues on the disaccharide backbone of lipid A. The fragmentation patterns of sodiated and protonated LPS molecules were investigated for determining the location of sialic acid. It was found that the tandem mass spectra of sodiated ions provided unambiguous evidence of both sialylated lactose and sialylated lacto-N-neotetraose. In contrast, the fragment ions of protonated ions only offered the evidence for the existence of sialylated lacto-N-neotetraose. The lipid A of Gram-negative bacteria, as the principal endotoxic component of LP S, plays a major role in the pathogenesis of bacterial infections. We have previously characterized lipid. A species after mild acid hydrolysis of LPS during which lipid A precipitates. In this study, intact LPS was directly introduced to a tandem mass spectrometer. In-source dissociation strategy was employed, followed by multiple-stage MS/MS on the ions originating from the lipid part to obtain structural information. This is the first time that the structure of lipid A of H. influenzae was characterized by MS/MS on intact LPS molecules without any prior chemical modifications. In the same way information on the OS can be obtained by MS/MS by focusing on ions originating from core OS.

  • 22. Ehn, M.
    et al.
    Ahmadian, Afshin
    KTH, Superseded Departments, Biotechnology.
    Nilsson, Peter
    KTH, Superseded Departments, Biotechnology.
    Lundeberg, Joakim
    KTH, Superseded Departments, Biotechnology.
    Hober, Sophia
    KTH, Superseded Departments, Biotechnology.
    Escherichia coli single-stranded DNA-binding a molecular tool for improved sequence protein quality in pyrosequencing2002In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 23, no 19, p. 3289-3299Article in journal (Refereed)
    Abstract [en]

    Pyrosequencing is a four-enzyme bioluminometric DNA sequencing technique based on a DNA sequencing by synthesis principle. Currently, the technique is limited to analysis of short DNA sequences exemplified by single-nucleotide polymorphism analysis. In order to expand the field for pyrosequencing, the read length needs to be improved and efforts have been made to purify reaction components as well as add single-stranded DNA-binding protein (SSB) to the pyrosequencing reaction. In this study, we have performed a systematic effort to analyze the effects of SSB by comparing the pyrosequencing result of 103 independent complementary DNA (cDNA) clones. More detailed information about the cause of low quality sequences on templates with different characteristics was achieved by thorough analysis of the pyrograms. Also, real-time biosensor analysis was performed on individual cDNA clones for investigation of primer annealing and SSB binding on these templates. Results from these studies indicate that templates with high performance in pyrosequencing without SSB possess efficient primer annealing and low SSB affinity. Alternative strategies to improve the performance in pyrosequencing by increasing the primer-annealing efficiency have also been evaluated.

  • 23.
    El Deeb, Sami
    et al.
    TU Braunschweig, Inst Med & Pharmaceut Chem, D-38106 Braunschweig, Germany..
    Waetzig, Hermann
    TU Braunschweig, Inst Med & Pharmaceut Chem, D-38106 Braunschweig, Germany..
    El-Hady, Deia Abd
    Univ Jeddah, Dept Chem, Fac Sci, Jeddah, Saudi Arabia.;Assiut Univ, Dept Chem, Fac Sci, Assiut, Egypt..
    Sänger-van de Griend, Cari
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry. Kantisto BV, Baarn, Netherlands.;Univ Tasmania, Australian Ctr Res Separat Sci ACROSS, Sch Chem, Hobart, Tas, Australia..
    Scriba, Gerhard K. E.
    Univ Jena, Sch Pharm, Dept Pharmaceut Med Chem, Jena, Germany..
    Recent advances in capillary electrophoretic migration techniques for pharmaceutical analysis (2013-2015)2016In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 37, no 12, p. 1591-1608Article, review/survey (Refereed)
    Abstract [en]

    This review updates and follows-up a previous review by highlighting recent advancements regarding capillary electromigration methodologies and applications in pharmaceutical analysis. General approaches such as quality by design as well as sample injection methods and detection sensitivity are discussed. The separation and analysis of drug-related substances, chiral CE, and chiral CE-MS in addition to the determination of physicochemical constants are addressed. The advantages of applying affinity capillary electrophoresis in studying receptor-ligand interactions are highlighted. Finally, current aspects related to the analysis of biopharmaceuticals are reviewed. The present review covers the literature between January 2013 and December 2015.

  • 24. El Deeb, Sami
    et al.
    Wätzig, Hermann
    Abd El-Hady, Deia
    Albishri, Hassan M.
    Sänger - van de Griend, Cari
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Scriba, Gerhard K. E.
    Recent advances in capillary electrophoretic migration techniques for pharmaceutical analysis2014In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 35, no 1, p. 170-189Article, review/survey (Refereed)
    Abstract [en]

    Since the introduction about 30 years ago, CE techniques have gained a significant impact in pharmaceutical analysis. The present review covers recent advances and applications of CE for the analysis of pharmaceuticals. Both small molecules and biomolecules such as proteins are considered. The applications range from the determination of drug-related substances to the analysis of counterions and the determination of physicochemical parameters. Furthermore, general considerations of CE methods in pharmaceutical analysis are described.

  • 25.
    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.

  • 26.
    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.

  • 27.
    Elhamili, Anisa
    et al.
    Uppsala University, Sweden.
    Samuelsson, Jörgen
    Uppsala universitet.
    Bergquist, Jonas
    Uppsala University, Sweden.
    Wetterhall, Magnus
    Uppsala University, Sweden.
    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 omega-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 6 min for all TCA analytes under the optimized condition with peak efficiencies up to 1.4 x 10(5) plates/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.

  • 28.
    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).

  • 29.
    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.

  • 30. Emmelkamp, J.
    et al.
    Wolbers, F.
    Andersson, Helene
    KTH, Superseded Departments, Biotechnology.
    DaCosta, R. S.
    Wilson, B. C.
    Vermes, I.
    van den Berg, A.
    The potential of autofluorescence for the detection of single living cells for label-free cell sorting in microfluidic systems2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 21-22, p. 3740-3745Article in journal (Refereed)
    Abstract [en]

    A novel method for studying unlabeled living mammalian cells based on their autofluorescence (AF) signal in a prototype microfluidic device is presented. When combined, cellular AF detection and microfluidic devices have the potential to facilitate high-throughput analysis of different cell populations. To demonstrate this, unlabeled cultured cells in microfluidic devices were excited with a 488 nm excitation light and the AF emission (> 505 nm) was detected using a confocal fluorescence microscope (CFM). For example, a simple microfluidic three-port glass microstructure was used together with conventional electroosmotic flow (EOF) to switch the direction of the fluid flow. As a means to test the potential of AF-based cell sorting in this microfluidic device, granulocytes were successfully differentiated from human red blood cells (RBCs) based on differences in AF This study demonstrated the use of a simple microfabricated device to perform high-throughput live cell detection and differentiation without the need for cell-specific fluorescent labeling dyes and thereby reducing the sample preparation time. Hence, the combined use of microfluidic devices and cell AF may have many applications in single-cell analysis.

  • 31.
    Emmer, Åsa
    et al.
    KTH, Superseded Departments, Chemistry.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Wall deactivation with fluorosurfactants for capillary electrophoretic analysis of biomolecules2001In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 22, no 4, p. 660-665Article in journal (Refereed)
    Abstract [en]

    This paper describes the use of fluorosurfactants as buffer additives for capillary electrophoretic separation of proteins and peptides. Due to fluorosurfactant bilayer formation at the capillary inner wall, the surface charge can be adjusted and even reversed. If the running buffer pH is kept at a level where the proteins have the same sign of charge as the wall, electrostatic repulsion will be obtained. The protein wall adsorption can therefore be reduced and the separation performance can be noticeably increased. The separation performance can also be further improved by including mixtures of different types of fluorosurfactants in the running buffer. The buffer system can accordingly be adapted for a certain separation problem. Mechanisms for the use of fluorosurfactants for wall deactivation in capillary electrophoretic protein separations is discussed in the present work and some examples of applications are also presented.

  • 32. Ericsson, O.
    et al.
    Sivertsson, A.
    Lundeberg, Joakim
    KTH, Superseded Departments, Biotechnology.
    Ahmadian, Afshin
    KTH, Superseded Departments, Biotechnology.
    Microarray-based resequencing by apyrase-mediated allele-specific extension2003In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 24, no 19-20, p. 3330-3338Article in journal (Refereed)
    Abstract [en]

    We have developed an array-based resequencing method to determine genetic alterations in putative cancer genes. The method relies on that the specificity of DNA polymerase in allele-specific extensions can be enhanced by terminating the extension reactions with apyrase and that a tiling set of primers are synthesized covering the investigated gene sequence. We report on such apyrase-mediated allele-specific primer extension (AMASE) assay as a method suitable for high-throughout resequencing and mutation detection in tumor suppressor genes and oncogenes. In the experimental setup, primers complementary to codons 12, 13 and codon 61 of the N-ras proto-oncogene were spotted onto glass slides. Overlapping sense and anti-sense primers were designed so that complementary primers for all possible mutations in each base position were investigated. The extension reactions were performed in a single step following hybridization of target DNA to the immobilized primers on the array surface. Mutation detection limits and the possibility of quantifying the mutations were investigated using synthetic oligonucleotides. In addition, 64 clinical samples were sequenced and 16 of these showed mutations in the N-ras gene.

  • 33.
    Eriksson, Björn
    et al.
    Karlstad University, Faculty of Technology and Science.
    Dahl, Magnus
    Karlstad University, Faculty of Technology and Science.
    Andersson, Magnus
    Department of Analytical Chemistry, Pharmaceutical and Analytical Research & Development, AstraZeneca, Sweden.
    Blomberg, Lars
    Karlstad University, Faculty of Technology and Science.
    Changes in mobile phase ion distribution when combining pressurized flow and electric field2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 18-19, p. 3092-3097Article in journal (Refereed)
  • 34.
    Eriksson, Jonas
    et al.
    KTH, Superseded Departments, Biotechnology.
    Gharizadeh, Baback
    KTH, Superseded Departments, Biotechnology.
    Nordström, Tommy
    KTH, Superseded Departments, Biotechnology.
    Nyrén, Pål
    KTH, Superseded Departments, Biotechnology.
    Pyrosequencing (TM) technology at elevated temperature2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 1, p. 20-27Article in journal (Refereed)
    Abstract [en]

    To date, the Pyrosequencing(TM) technology has been performed at 28degreesC due to the low thermostability of the firefly luciferase. In this study, firefly luciferase was stabilized in the presence of glycine betaine, allowing DNA sequencing at 37degreesC. By increasing the temperature to 37degreesC, false signals due to primer-dimers and loop-structures were decreased significantly. In addition, a combination of (i) replacing the natural dGTP with 7'deaza-dGTP in the polymerase chain reaction (PCR), (ii) 1.6 m glycine betaine, and (iii) an increase of the temperature to 37degreesC enabled us to sequence a DNA template with the initial sequence 3'-ATGGCCCGGGGGGGAGCTCCA . . . 5'. Furthermore, we describe a method to analyze if a primer forms a primer-dimer with extendable 3'-ends.

  • 35.
    Eriksson, Jonas
    et al.
    Department of Biotechnology, Stockholm Center for Physics, Astronomy and Biotechnology (SCFAB), Stockholm.
    Gharizadeh, Baback
    Department of Biotechnology, Stockholm Center for Physics, Astronomy and Biotechnology (SCFAB), Stockholm.
    Nordström, Tommy
    Department of Biotechnology, Stockholm Center for Physics, Astronomy and Biotechnology (SCFAB), Stockholm.
    Nyrén, Pål
    Department of Biotechnology, Stockholm Center for Physics, Astronomy and Biotechnology (SCFAB), Stockholm.
    Pyrosequencing trade mark technology at elevated temperature2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 1, p. 20-27Article in journal (Refereed)
    Abstract [en]

    To date, the Pyrosequencing trade mark technology has been performed at 28 degrees C due to the low thermostability of the firefly luciferase. In this study, firefly luciferase was stabilized in the presence of glycine betaine, allowing DNA sequencing at 37 degrees C. By increasing the temperature to 37 degrees C, false signals due to primer-dimers and loop-structures were decreased significantly. In addition, a combination of (i) replacing the natural dGTP with 7'deaza-dGTP in the polymerase chain reaction (PCR), (ii) 1.6 M glycine betaine, and (iii) an increase of the temperature to 37 degrees C enabled us to sequence a DNA template with the initial sequence 3'-ATGGCCCGGGGGGGAGCTCCA em leader 5'. Furthermore, we describe a method to analyze if a primer forms a primer-dimer with extendable 3'-ends.

  • 36.
    Frisk, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Rydholm, Susanna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Andersson, Helene
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    A concept for miniaturized 3-D cell culture using an extracellular matrix gel2005In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 26, no 24, p. 4751-4758Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel method to embed, anchor, and cultivate cells in a controlled 3-D flow-through microenvironment. This is realized using an etched silicon pillar flow chamber filled with extracellular matrix (ECM) gel mixed with cells. At 4 degrees C, while in liquid form, ECM gel is mixed with cells and injected into the chamber. Raising the temperature to 37 degrees C results in a gel, with cells embedded. The silicon pillars both stabilize and increase the surface to volume ratio of the gel. During polymerization the gel shrinks, thus creating channels, which enables perfusion through the chip. The pillars increase the mechanical stability of the gel permitting high surface flow rates without surface modifications. Within the structure cells were still viable and proliferating after 6 days of cultivation. Our method thus makes it possible to perform medium- to long-term cultivation of cells in a controlled 3-D environment. This concept opens possibilities to perform studies of cells in a more physiological environment compared to traditional 2-D cultures on flat substrates.

  • 37.
    Frisk, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Rydholm, Susanna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Liebmann, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    A microfluidic device for parallel 3-D cell cultures in asymmetric environments2007In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 28, no 24, p. 4705-4712Article in journal (Refereed)
    Abstract [en]

    We demonstrate a concept for how a miniaturized 3-D cell culture in biological extracellular matrix (ECM) or synthetic gels bridges the gap between organ-tissue culture and traditional 2-D cultures. A microfluidic device for 3-D cell culture including microgradient environments has been designed, fabricated, and successfully evaluated. In the presented system stable diffusion gradients can be generated by application of two parallel fluid flows with different composition against opposite sides of a gel plug with embedded cello. Culture for up to two weeks was performed showing cells still viable and proliferating. The cell tracer dye calcein was used to verify gradient formation as the fluorescence intensity in exposed cells was proportional to the position in the chamber. Cellular response to an applied stimulus was demonstrated by use of an adenosine triphosphate gradient where the onset of a stimulated intracellular calcium release also depended on cell position.

  • 38. Gharizadeh, B.
    et al.
    Ghaderi, M.
    Donnelly, D.
    Amini, B.
    Wallin, K. L.
    Nyrén, Pål
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Multiple-primer DNA sequencing method2003In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 24, no 08-jul, p. 1145-1151Article in journal (Refereed)
    Abstract [en]

    A multiple-primer DNA sequencing approach suitable for genotyping, detection and identification of microorganisms and viruses has been developed. In this new method two or m ore sequencing primers, combined in a pool, are added to a DNA sample of interest. The oligonucleotide that hybridizes to the DNA sample will function as a primer during the subsequent DNA sequencing procedure. This strategy is suited for selective detection and genotyping of relevant microorganisms and samples harboring different DNA targets such as,multiple variant/infected samples as well as unspecific amplification products. This method is used here in a model system for detection and typing of high-risk oncogenic human papilloma viruses (HPVs) in samples containing multiple infections/variants or unspecific amplification products. Type-specific sequencing primers were designed for four of the most oncogenic (high-risk) HPV types (HPV-16, HPV-18, HPV-33, and HPV-45). The primers were combined and added to a sample containing a mixture of one high-risk (16, 18, 33, or 45) and one or two low-risk types. The DNA samples were sequenced by the Pyrosequencing(TM) technology and the Sanger dideoxy sequencing method. Correct genotyping was achieved in all tested combinations. This multiple-sequencing primer approach also improved the sequence data quality for samples containing unspecific amplification products. The new strategy is highly suitable for diagnostic typing of relevant species/genotypes of microorganisms.

  • 39.
    Ghasemzadeh, Nasim
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Tore W. Wilhelmsen, Tore W.
    Norwegian Medicines Agency.
    Nyberg, Fred
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Hjertén, Stellan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry.
    Precautions to improve the accuracy of quantitative determinations of biomarkers in clinical diagnostics2010In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 31, no 16, p. 2722-2729Article in journal (Refereed)
    Abstract [en]

    Although protein biomarkers have a great potential as biomarkers for diagnosis of diseases, they are seldom used in hospitals. There are many reasons for this, for instance, the difficulties to (i) find a biomarker for which the concentration in body fluids clearly differs between patients and healthy subjects, (ii) attain purification of the biomarker close to 100%, which is required for production of conventional protein antibodies as well as artificial gel antibodies for selective capture of a biomarker, (iii) design a standard curve for rapid and accurate determination of the concentration of the biomarker in the body fluid because of adsorption of the biomarker onto vials, pipettes, etc., (iv) determine accurately the sample volume delivered by a pipette, (v) avoid polymerization of the biomarker upon storage and to decide whether it is in the form not only of monomers, but also of dimers, trimers, etc., in the native state, (vi) determine the degree of possible glycosylation and amidation of the biomarker and (vii) decide whether glycosylation and amidation positively or negatively affects the possibility to use the protein as a biomarker. In this article, we discuss in quantitative terms the difficulties (iii-vii) and how to overcome them, which also may help to overcome the difficulty (ti), which in turn minimizes difficulty (i).

  • 40.
    Haglöf, Jakob
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Pettersson, Curt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Separation of amino alcohols using divalent dipeptides as counter ions in aqueous CE2010In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 31, no 10, p. 1706-1712Article in journal (Refereed)
    Abstract [en]

    Divalent dipeptides have been introduced as counter ions in aqueous CZE. The dipeptides form ion pairs with amino alcohols in the BGE and facilitate the separation of amino alcohols. High concentrations of dipeptide caused reversed effective mobility for the analytes. The net charge of the dipeptide can be controlled using a buffer or a strong base, and regulates the interaction between the dipeptide and the amino alcohol. A stronger interaction and higher selectivity of amino alcohols was observed when the dipeptides were used as divalent counter ions, than in monovalent or uncharged form. Association constants for ion pairs between divalent dipeptides and amino alcohols can be used to enhance selectivity for amino alcohols in CZE. No chiral separation of amino alcohols was observed when using the dipeptides as ion-pairing chiral selectors in aqueous BGE, but addition of methanol to the BGE promoted enantioselectivity.

  • 41. Hanning, A.
    et al.
    Westberg, J.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    A liquid core waveguide fluorescence detector for multicapillary electrophoresis applied to DNA sequencing in a 91-capillary array2000In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 21, no 15, p. 3290-3304Article in journal (Refereed)
    Abstract [en]

    A new laser-induced fluorescence (LIF) detector for multicapillary electrophoresis is presented. The detection principle is based on waveguiding of the emitted fluorescence from the point of illumination to the capillary ends by total internal reflection (TIR) and imaging of the capillary ends. The capillaries themselves thus act as liquid core waveguides (LCWs). At the illumination point, the capillaries are arranged in a planar array, which allows clean and efficient illumination with a line-focused laser beam. The capillary ends are rearranged into a small, densely packed two-dimensional array, which is imaged end-on with high light collection efficiency and excellent image quality. Wavelength dispersion is obtained with a single prism. Intercapillary optical crosstalk is less than 0.5%, and rejection of stray light is very efficient. The detector is applied to four-color DNA sequencing by gel electrophoresis in a 91-capillary array, with simple fluorescein and rhodamine dyes as fluorophores. Since the imaged two-dimensional array is so compact, the detector has a high potential for very large-scale multiplexing.

  • 42.
    Harang, Valérie
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Eriksson, Jessica
    Sänger-van de Griend, Cari
    Jacobsson, Sven P.
    Westerlund, Douglas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Microemulsion electrokinetic chromatography of drugs varying in charge and hydrophobicity: I. Impact of parameters on separation performance evaluated by multiple linear regression models2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 1, p. 80-93Article in journal (Refereed)
    Abstract [en]

    The separation of anionic, cationic and neutral drugs in microemulsion electrokinetic chromatography (MEEKC) was studied with a statistical experimental design. The concentration of sodium dodecyl sulfate (SDS, surfactant), 1-butanol (co-surfactant) and borate buffer and the factors Brij 35 (surfactant), 2-propanol (organic solvent) and cassette temperature were varied simultaneously, while the parameters pH (9.2), the concentration of octane (oil, 0.8% w/w), the voltage (10 kV) and the dimension of the fused-silica capillary, were kept constant. Eight different model substances were chosen with different hydrophobicities. Two of the analytes were positively charged, two were negatively charged, and the remaining four were neutral or close to neutral at the pH explored. The importance of each parameter on the separation window, the plate height and the retention factor for each of the analytes was studied by means of multiple linear regression (MLR) models. A new response was evaluated for anions, the quotient between the effective mobility in the microemulsion and the effective mobility in the corresponding buffer. Factors affecting selectivity changes were also explored, and it was found that SDS and 2-propanol had the largest effect on selectivity.

  • 43.
    Harang, Valérie
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Jacobsson, Sven P.
    Westerlund, Douglas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Microemulsion electrokinetic chromatography of drugs varying in charge and hydrophobicity: II. Strategies for optimisation of separation2004In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, no 12, p. 1792-1809Article in journal (Refereed)
    Abstract [en]

    The separation of anionic, cationic, and neutral drugs in microemulsion electrokinetic chromatography (MEEKC) was studied. The concentration of sodium dodecyl sulfate (SDS; surfactant) and 2-propanol (organic solvent) was varied in a three-level full factorial design. 29 different model substances were chosen with different hydrophobicities and charges (neutral, positive, and negative). The models were calculated by means of multiple linear regression (MLR). The compounds were divided into five different subgroups, and different strategies for optimization of the separation within each group were investigated. The optimization was done by maximizing the selectivity using response surface plots in MODDE, by calculation of different chromatographic functions, and by using the software DryLab. For all the different groups, MODDE, almost all chromatographic functions and DryLab gave approximately the same settings of the factors for optimum separation. Attempts were made to fit descriptors of the compounds to the retention data from the three-level full factorial design by means of partial least squares projection to latent structures (PLS). Between 86 and 89% of all predictions of migration times were acceptable (80-120% of the observed value).

  • 44. Harang, Valérie
    et al.
    Tysk, Marcus
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Westerlund, Douglas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Isaksson, Roland
    Johansson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    A statistical experimental design to study factors affecting enantioseparation of propranolol by capillary electrophoresis with cellobiohydrolase (Cel7A) as chiral selector.2002In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 23, no 14, p. 2306-2319Article in journal (Refereed)
    Abstract [en]

    The capillary electrophoretic enantioseparation of rac-propranolol using cellobiohydrolase Tr Cel7A as selector was optimized by an unbiased statistical experimental design. A set of pre-experiments was performed in order to identify critical experimental factors. In the definitive chemometric design pH, ranging from 5 to 7, ionic strength ranging between 0.01 and 0.02 and organic solvent additive in concentration from 1 to 19% v/v were studied. The response surface plot revealed a separation optimum in the pH interval studied. When all parameters were taken into account, a background electrolyte consisting of 0.016 M bistris-acetate buffer with pH 6.5 and 17% v/v acetonitrile gave the optimum separation. The significance of the statistical design was confirmed by the generally good agreement obtained between predicted response and actual experimental data.

  • 45.
    Hedeland, Ylva
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Haglöf, Jakob
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Beronius, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Pettersson, Curt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Effect of alkali metal hydroxides on the enantioseparation of amines using di-O-isopropylidene-keto-L-gulonic acid as the selector in NACE2006In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 27, no 22, p. 4469-4479Article in journal (Refereed)
    Abstract [en]

    The present work demonstrates the importance of the ionic composition in the BGE for enantioseparation. (-)-2,3:4,6-di-O-Isopropylidene-2-keto-L-gulonic acid ((-)-DIKGA) has been used as the chiral selector in methanolic and ethanolic BGEs. The influence of added alkali metal hydroxides on the EOF and the chiral separation of amines; (atenolol, isoprenaline, pindolol and propranolol) have been studied. The ion-pair formation constants in ethanol were determined by precision conductometry for the enantiomers of pindolol with (-)-DIKGA, for Li+, Na+ and Cs+ with (-)-DIKGA, and also for the corresponding alkali metal hydroxides. The effective mobilities and the enantiomeric mobility differences were affected by the type of alkali metal hydroxide (LiOH, NaOH, KOH, RbOH or CsOH) added to the BGE. The effective mobility and mobility difference were increased with decrease in solvated radius of the alkali metal cation. These differences could partly be correlated to the ion-pair formation constants of the alkali metal cations with the chiral selector, affecting the equilibrium concentration of the free selector. The electroosmosis was also affected by the alkali metal hydroxide added to the BGE. The cathodic electroosmosis decreased with decreasing solvated radius of the alkali metal cation added to the BGE. Interestingly, the cathodic EOF was even reversed, i.e. became anodic in the ethanolic BGEs containing KOH, RbOH or CsOH and the methanolic ones with RbOH and CsOH.

  • 46.
    Hellqvist, Alexander
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Hedeland, Ylva
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Pettersson, Curt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Evaluation of electroosmotic markers in aqueous and nonaqueous capillary electrophoresis2013In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 34, no 24, p. 3252-3259Article in journal (Refereed)
    Abstract [en]

    The most common method to determine the EOF in CE is to measure the migration time for a neutral marker. In this study, 12 compounds (three novel and some previously used) were investigated as EOF markers in aqueous and nonaqueous BGEs. In the aqueous buffer systems (ammonium acetate, sodium phosphate, and sodium borate) the evaluation included a wide pH range (2-12). Two BGEs contained chiral selectors (sulphated-β-CD, (-)-diketogulonic acid) and one that contained a micellar agent (SDS) were included in the study. The majority of the evaluated compounds were found to migrate with the EOF in the water-based BGEs and are thus useful as EOF markers. However, in the SDS-based BGE only four of the compounds (acetone, acrylamide, DMSO, and ethanol) were found to be applicable. In the nonaqueous BGEs 11 markers (acetone, acetophenone, acrylamide, anthracene, benzene, 4-(4-methoxybenzylamino)-7-nitro-2,1,3-benzoxadiazole, benzyl alcohol, 2,5-diphenyloxazole, ethanol, flavone, and mesityl oxide) seemed to be functional as EOF markers. Even though several of the evaluated compounds can be used as EOF markers in the investigated BGEs, the authors would recommend the use of acrylamide as a general marker for UV detection. Furthermore, the four fluorescent markers (of which three were novel) gave RSD values equal to the other markers and can be used for the determination of the EOF in CE or microchip CE with fluorescence detection.

  • 47.
    Henry, Olivier
    et al.
    Universitat Rovira I Virgili, Tarragona, Spain.
    Fragoso, Alex
    Universitat Rovira I Virgili, Tarragona, Spain.
    Beni, Valerio
    Universitat Rovira I Virgili, Tarragona, Spain.
    Laboria, Noemi
    Universitat Rovira I Virgili, Tarragona, Spain.
    Acero Sanchez, Jose Luis
    Universitat Rovira I Virgili, Tarragona, Spain.
    Latta, Daniel
    Institut für Mikrotechnik Mainz GmbH, Mainz, Germany.
    Von Germar, Frithoj
    Institut für Mikrotechnik Mainz GmbH, Mainz, Germany.
    Drese, Klaus
    Institut für Mikrotechnik Mainz GmbH, Mainz, Germany.
    Katakis, Ioanis
    Universitat Rovira I Virgili, Tarragona, Spain.
    O´Sullivan, Ciara K.
    Universitat Rovira I Virgili, Tarragona, Spain.
    Design and testing of a packaged microfluidic cell for the multiplexed electrochemical detection of cancer markers2009In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 30, no 19, p. 3398-3405Article in journal (Refereed)
    Abstract [en]

    We present the rapid prototyping of electrochemical sensor arrays integrated to microfluidicstowards the fabrication of integrated microsystems prototypes for point-of-carediagnostics. Rapid prototyping of microfluidics was realised by high-precision milling ofpolycarbonate sheets, which offers flexibility and rapid turnover of the desired designs. Onthe other hand, the electrochemical sensor arrays were fabricated using standard photolithographicand metal (gold and silver) deposition technology in order to realise threeelectrodecells comprising gold counter and working electrodes as well as silver referenceelectrode. The integration of fluidic chips and electrode arrays was realised via a lasermachineddouble-sided adhesive gasket that allowed creating the microchannels necessaryfor sample and reagent delivery. We focused our attention on the reproducibility of theelectrode array preparation for the multiplexed detection of tumour markers such ascarcinoembryonic antigen and prostate-specific antigen as well as genetic breast cancermarkers such as estrogen receptor-a, plasminogen activator urokinase receptor, epidermalgrowth factor receptor and erythroblastic leukemia viral oncogene homolog 2. We showedthat by carefully controlling the electrode surface pre-treatment and derivatisation viathiolated antibodies or short DNA probes that the detection of several key health parameterson a single chip was achievable with excellent reproducibility and high sensitivity.

  • 48. Holmberg, A.
    et al.
    Blomstergren, A.
    Nord, O.
    Lukacs, M.
    Lundeberg, Joakim
    KTH, School of Biotechnology (BIO), Gene Technology.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics.
    The biotin-streptavidin interaction can be reversibly broken using water at elevated temperatures2005In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 26, no 3, p. 501-510Article in journal (Refereed)
    Abstract [en]

    The biotin-streptavidin system is the strongest noncovalent biological interaction known, having a dissociation constant, K-d, in the order of 4 x 10(-14) m. The strength and specificity of the interaction has led it to be one of the most widely used affinity pairs in molecular, immunological, and cellular assays. However, it has previously been impossible to re-use any streptavidin solid support, since the conditions needed to break the interaction with biotin has led to the denaturation of the streptavidin. Here, we show that a short incubation in nonionic aqueous solutions at temperatures above 70degreesC can efficiently break the interaction without denaturing the streptavidin tetramer. Both biotin and the streptavidin remain active after dissociation and both molecules can therefore be re-used. The efficiency of the regeneration allowed solid supports with streptavidin to be used many times, here exemplified with the multiple re-use of streptavidin beads used for sample preparation prior to automated DNA sequencing. The results suggest that streptavidin regeneration can be introduced as an improvement in existing methods and assays based on the streptavidin system as well as emerging solid phase applications in fields, such as microfluiclics and nanotechnology.

  • 49.
    Jacksén, Johan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Frisk, Thomas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Redeby, Theres
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Parmar, Varun
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Off-line integration of CE and MALDI-MS using a closed-open-closed microchannel system2007In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 28, no 14, p. 2458-2465Article in journal (Refereed)
    Abstract [en]

    In this work, a new technique for off-line hyphenation between CE and MALDI-MS is presented. Two closed fused-silica capillaries were connected via a silicon chip comprising an open microcanal. The EOF in the system was evaluated using mesityloxide or leucine-enkephalin as a sample and with a running buffer that rendered the analyte neutrally charged. Comparison was made between the EOF in a closed system (first capillary solely included in the electrical circuit) and in a closed-open system (first capillary and microcanal included in the electrical circuit). It was concluded that the experimental values of the EOF agreed with the theory. The influence of the capillary outer diameter on the peak dispersion was investigated using a closed-open-closed system (first capillary, microcanal and second capillary included in the electrical circuit). It was clearly seen that a capillary with 375 mu m od induced considerably higher peak dispersion than a 150 mu m od capillary, due to a larger liquid dead volume in the connection between the first capillary outlet and the microcanal. Mass spectrometric analysis has also been performed following CE separation runs in a closed-open-closed system with cytochrome c and lysozyme as model proteins. It was demonstrated that a signal distribution profile of the separated analytes could be recorded over a 30 mm long microcanal.

  • 50. Jarmalavičienė, Reda
    et al.
    Szumski, Michał
    Kornyšova, Olga
    Kłodzińska, Ewa
    Westerlund, Douglas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Analytisk Farmaceutisk Kemi.
    Krawczyk, Stanislas
    Mickevičius, Donatas
    Buszewski, Bogusław
    Maruška, Audrius
    Coupling of solid-phase microextraction continuous bed (monolithic) capillaries with capillary zone electrophoresis for direct analysis of drugs in biological fluids.2008In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 29, no 8, p. 1753-1760Article in journal (Refereed)
    Abstract [en]

    Hyperlink robust biocompatible solid-phase microextraction (SPME) devices were prepared using continuous bed (monolithic) restricted-access media (RAM) as the SPME capillary insert The RAM-based SPME approach was able to simultaneously separate proteins from a biological sample, while directly extracting the active components of caffeine, paracetamol and acetylsalicylic acid from the drug NeoCitramonum. The devices were interfaced with a CZE system and fully automated analysis for sample preconcentration, desorption, separation and quantification of analytes was evaluated. Comparative study of in-line coupled SPME-CZE using RAM and RP capillary inserts was carried out. Using an SPME (RAM) insert, the calculated caffeine, paracetamol and acetylsalicylic acid LODs in a bovine plasma sample were 0.3, 0.8 and 1.9 ng/mL, respectively.

123 1 - 50 of 103
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf