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    Preparation and characterization of polymer coated superparamagnetic magnetite nanoparticle agglomerates
    (Pergamon-Elsevier Science Ltd, 2009) Tural, Bilsen; Ozkan, Necati; Volkan, Murvet
    In order to produce magnetic microparticles (agglomerates), magnetite (Fe3O4) particles were synthesized using coprecipitation of FeSO4 center dot 7H(2)O and FeCl3 center dot 6H(2)O with the presence of poly (methacrylic acid) (PMAA) in aqueous solution.. Transmission electron microscopy (TEM), X-ray diffraction, and vibrating sample magnetometry (VSM) methods were used to characterize the PMAA coated superparamagnetic agglomerates. The influences of various processing parameters such as the process temperature, PMAA content, and the addition of surfactant on the agglomerate size and size distribution of produced magnetic microparticles were investigated. The particle size and size distribution characteristics, (the volume weighted mean size (1)[4,31, surface weighted mean size D[3,2], the geometric standard deviation, and span value) of the magnetic agglomerates were determined using the laser diffraction technique. The PMAA coated magnetic agglomerates with surface weighted mean sizes ranging from 1.5 to 3 mu m were produced successfully. (C) 2009 Elsevier Ltd. All rights reserved.
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    Öğe
    Preparation and characterization of surface modified ?-Fe2O3 (maghemite)-silica nanocomposites used for the purification of benzaldehyde lyase
    (Pergamon-Elsevier Science Ltd, 2011) Tural, Bilsen; Sopaci, S. Betul; Ozkan, Necati; Demir, Ayhan S.; Volkan, Murvet
    gamma-Fe2O3 (maghemite)-silica nanocomposite particles were synthesized using a sol-gel method. The condensation products of 3-glycidoxy propyltrimethoxy silane (GPTMS) and nitrilotriacetic acid (NTA) were introduced onto the surfaces of the gamma-Fe2O3 silica nanocomposite particles and subsequently, these modified surfaces were complexed with cobalt (Co+2) metal ions. A possibility of using these surface modified gamma-Fe2O3-silica particles for the purification of 6 x histidine tagged recombinant benzaldehyde lyase (BAL, EC 4.1.2.38) based on magnetic separation was investigated. X-ray diffraction (XRD), thermal analysis, and vibrating sample magnetometry (VSM) methods were used to characterize the surface modified superparamagnetic gamma-Fe2O3 (maghemite)-silica nanoparticles. XRD (Scherer's equation) results indicate that the primary particle size of maghemite was around 11 nm. Magnetic characterization results confirmed that the gamma-Fe2O3 (maghemite)-silica nanoparticles were superparamagnetic. According to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results, these superparamagnetic nanoparticles specifically capture 6 x His-tagged BAL from crude extract of Escherichia coli (E. coli) BL21(DE3)pLysS/BAL(HIS). This study shows that the surface modified gamma-Fe2O3 (maghemite)-silica nanoparticles are eligible for immobilized metal-ion affinity adsorption for histidine tagged recombinant proteins with its high capacity (3.16 +/- 0.4 mg/g) and selectivity. (C) 2011 Elsevier Ltd. All rights reserved.