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  • 1.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Two new techniques for sample preparation in bioanalysis: Microextraction in packed sorbent (MEPS) and use of a bonded monolith as sorbent for sample preparation in polypropylene tips for 96-well plates2009In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 393, no 3, p. 797-807Article in journal (Refereed)
  • 2.
    Enmark, Martin
    et al.
    Karlstad Univ, Dept Engn & Chem Sci, S-65188 Karlstad, Sweden.;Uppsala Univ, Biomed Ctr, Dept Med Chem, Pharmacognosy, Box 574, S-75123 Uppsala, Sweden..
    Bagge, Joakim
    Karlstad Univ, Dept Engn & Chem Sci, S-65188 Karlstad, Sweden..
    Samuelsson, Jorgen
    Karlstad Univ, Dept Engn & Chem Sci, S-65188 Karlstad, Sweden..
    Thunberg, Linda
    AstraZeneca, BioPharmaceut R&D, Pharmaceut Sci, Early Chem Dev, S-43183 Molndal, Sweden..
    Ornskov, Eivor
    AstraZeneca, BioPharmaceut R&D, Pharmaceut Sci, Adv Drug Delivery, S-43183 Molndal, Sweden..
    Leek, Hanna
    AstraZeneca, BioPharmaceut R&D, Pharmaceut Sci, Early Chem Dev, S-43183 Molndal, Sweden..
    Lime, Fredrik
    Nouryon, Separat Prod, S-44580 Bohus, Sweden..
    Fornstedt, Torgny
    Karlstad Univ, Dept Engn & Chem Sci, S-65188 Karlstad, Sweden..
    Analytical and preparative separation of phosphorothioated oligonucleotides: columns and ion-pair reagentsIn: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650Article in journal (Refereed)
    Abstract [en]

    Oligonucleotide drugs represent an emerging area in the pharmaceutical industry. Solid-phase synthesis generates many structurally closely related impurities, making efficient separation systems for purification and analysis a key challenge during pharmaceutical drug development. To increase the fundamental understanding of the important preparative separation step, mass-overloaded injections of a fully phosphorothioated 16mer, i.e., deoxythymidine oligonucleotide, were performed on a C18 and a phenyl column. The narrowest elution profiles were obtained using the phenyl column, and the 16mer could be collected with high purity and yield on both columns. The most likely contribution to the successful purification was the quantifiable displacement of the early-eluting shortmers on both columns. In addition, the phenyl column displayed better separation of later-eluting impurities, such as the 17mer impurity. The mass-overloaded injections resulted in classical Langmuirian elution profiles on all columns, provided the concentration of the ion-pairing reagent in the eluent was sufficiently high. Two additional column chemistries, C4 and C8, were also investigated in terms of their selectivity and elution profile characteristics for the separation of 520mers fully phosphorothioated deoxythymidine oligonucleotides. When using triethylamine as ion-pairing reagent to separate phosphorothioated oligonucleotides, we observed peak broadening caused by the partial separation of diastereomers, predominantly seen on the C4 and C18 columns. When using the ion-pair reagent tributylamine, to suppress diastereomer separation, the greatest selectivity was found using the phenyl column followed by C18. The present results will be useful when designing and optimizing efficient preparative separations of synthetic oligonucleotides.

  • 3.
    Enmark, Martin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Uppsala University.
    Rova, Maria
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Samuelsson, Jörgen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Örnskov, Eivor
    IMED Biotech Unit, Sweden.
    Schweikart, Fritz
    IMED Biotech Unit, Sweden.
    Fornstedt, Torgny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Investigation of factors influencing the separation of diastereomers of phosphorothioated oligonucleotides2019In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 411, no 15, p. 3383-3394Article in journal (Refereed)
    Abstract [en]

    This study presents a systematic investigation of factors influencing the chromatographic separation of diastereomers of phosphorothioated pentameric oligonucleotides as model solutes. Separation was carried out under ion-pairing conditions using an XBridge C18 column. For oligonucleotides with a single sulfur substitution, the diastereomer selectivity was found to increase with decreasing carbon chain length of the tertiary alkylamine used as an ion-pair reagent. Using an ion-pair reagent with high selectivity for diastereomers, triethylammonium, it was found the selectivity increased with decreased ion-pair concentration and shallower gradient slope. Selectivity was also demonstrated to be dependent on the position of the modified linkage. Substitutions at the center of the pentamer resulted in higher diastereomer selectivity compared to substitutions at either end. For mono-substituted oligonucleotides, the retention order and stereo configuration were consistently found to be correlated, with Rp followed by Sp, regardless of which linkage was modified. The type of nucleobase greatly affects the observed selectivity. A pentamer of cytosine has about twice the diastereomer selectivity of that of thymine. When investigating the retention of various oligonucleotides eluted using tributylammonium as the ion-pairing reagent, no diastereomer selectivity could be observed. However, retention was found to be dependent on both the degree and position of sulfur substitution as well as on the nucleobase. When analyzing fractions collected in the front and tail of overloaded injections, a significant difference was found in the ratio between Rp and Sp diastereomers, indicating that the peak broadening observed when using tributylammonium could be explained by partial diastereomer separation.

  • 4.
    Lipponen, Katriina
    et al.
    Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Helsinki, Finland.
    Tähkä, Sari
    Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Helsinki, Finland.
    Samuelsson, Jörgen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Jauhiainen, Matti
    National Institute for Health and Welfare and FIMM, Institute of Molecular Medicine Finland, Biomedicum, Haartmaninkatu 8, FIN-00290 Helsinki,.
    Metso, Jari
    National Institute for Health and Welfare and FIMM, Institute of Molecular Medicine Finland, Biomedicum, Haartmaninkatu 8, FIN-00290 Helsinki, Finland,.
    Cilpa-Karhu, Geraldine
    Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Helsinki, Finland.
    Fornstedt, Torgny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Kostiainen, Mauri
    Biohybrid Materials, Department of Biotechnology and Chemical Technology, FIN-00076 Aalto University, Espoo, Finland.
    Riekkola, Marja-Liisa
    Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Helsinki, Finland.
    Partial-filling affinity capillary electrophoresis and quartz crystal microbalance with adsorption energy distribution calculations in the study of biomolecular interactions with apolipoprotein E as interaction partner2014In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 406, no 17, p. 4137-4146Article in journal (Refereed)
    Abstract [en]

    Adsorption energy distribution (AED) calculations were successfully applied to partial-filling affinity capillary electrophoresis (PF-ACE) to facilitate more detailed studies of biomolecular interactions. PF-ACE with AED calculations was employed to study the interactions between two isoforms of apolipoprotein E (apoE) and dermatan sulfate (DS), and a quartz crystal microbalance (QCM) was used in combination with AED calculations to examine the interactions of the 15-amino-acid peptide fragment of apoE with DS. The heterogeneity of the interactions was elucidated. Microscale thermophoresis was used to validate the results. The interactions studied are of interest because, in vivo, apolipoprotein E localizes on DS-containing regions in the extracellular matrix of human vascular subendothelium. Two-site binding was demonstrated for the isoform apoE3 and DS, but only one-site binding for apoE2–DS. Comparable affinity constants were obtained for the apoE2–DS, apoE3–D3, and 15-amino-acid peptide of apoE–DS using the three techniques. The results show that combining AED calculations with modern biosensing techniques can open up another dimension in studies on the heterogeneity and affinity constants of biological molecules.

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