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    Megaporous poly(hydroxy ethylmethacrylate) based poly(glycidylmethacrylate-N-methacryloly-(L)-tryptophan) embedded composite cryogel
    (Elsevier Science Bv, 2015) Türkmen, Deniz; Bereli, Nilay; Derazshamshir, Ali; Perçin, Işık; Shaikh, Huma; Yılmaz, Fatma
    One-step activation, purification, and stabilization of lipase enzyme were performed by using composite hydrophobic support at low ionic strength with increased surface area during embedding process. A novel hydrophobic poly(hydroxyethylmethacrylate) [PHEMA] based, poly(glycidyl methacrylate-N-methacryloly-(L)-tryptophan) [PGMATrp] bead embedded composite cryogel membrane having specific surface area of 195 m(2)/g was used as hydrophobic matrix for adsorption of commercial Candida Rugosa lipase in a continuous system. PGMATrp embedded PHEMA cryogel membrane with 60-100 mu m pore size was obtained by dispersion polymerization of GMA and MATrp to form PGMATrp beads followed by embedding of PGMATrp to HEMA via APS and TEMED redox pair. The introduction of hydrophobic MATrp monomer into bead structure aiming to increase interaction between lipase and composite membrane was estimated using nitrogen stoichiometry of elemental analysis and found to be 239 mu mol/g of polymer. Hydophobicity increment due to embedding process was confirmed by measuring contact angle, it was found 42 degrees and 48.4 degrees for the PHEMA and PHEMA/PGMATrp composite cryogel respectively. Some parameters i.e. pH, flow-rate, protein concentration, temperature, salt type and ionic intensity were evaluated on the adsorption capacity in a continuous system. Fast protein liquid chromatography (FPLC) studies were performed for specific adsorption of lipase onto the PHEMA/PGMATrp embedded composite cryogel membrane. (C) 2015 Elsevier B.V. All rights reserved.
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    Study on an Hydrophilic Interaction Electrochromatography Method for Separation of Sulfonamide Antibiotics
    (2014) Aydoğan, Cemil; Yılmaz, Fatma; Çimen, Duygu; Andaç, Müge; Shaikh, Huma; Denizli, Adil
    This study describes the preparation of a hydrophilic monolithic column and its application to sulfonamide antibiotics. The column was prepared by single step in situ polymerization of 2-hydroxyethyl methacrylate (HEMA), ethylene dimethacrylate (EDMA) and methacrylic acid (MAA) in a binary porogenic solvent consisting of toluene and 1-dodecanol, inside a 100 µm-i.d. capillary. The resulting monolith was electrochromatographically characterized as well as SEM. The prepared column showed hydrophilic behaviour using thiourea and toluene as markers. The SEM images showed that the monolithic column composed of spherical particles of approximately 2 µm in diameter. Using this hydrophilic monolith as stationary phase, hydrophilic interaction electrochromatography of sulfonamide antibiotics as a new method was developed. The method was successfully used for the separation of sulfonamide antibiotics. Some parameters including acetonitrile (ACN) content, pH and ionic strength on the separation of the sulfonamides, namely sulfaprydine, sulfadiazine, sulfamethazine, sulfisoxazole and sulfadoxine were also investigated. A typical hydrophilic interaction separation mechanism was revealed at higher organic solvent content (ACN > 60%).