• MURAT UYGUN

      Articles written in Bulletin of Materials Science

    • Hydrophobic nano-carrier for lysozyme adsorption

      CANAN ALTUNBAS FULDEN ZEYNEP URAL MURAT UYGUN NESIBE AVCIBASI UGUR AVCIBASI DENIZ AKTAS UYGUN SINAN AKGÖL

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      In this work, poly(HEMA–APH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique.Magnetic behaviour was introduced by simple addition of Fe$_3$O$_4$ into the polymerization medium.Characterization of the nanoparticle was carried out by FTIR, ESR, SEM, AFM and EDX analyses. These synthesized magnetic nanoparticles were used for adsorption of lysozyme. For this purpose, adsorption conditions wereoptimized and maximum lysozyme binding capacity was found to be 278.8 mg g$^{−1}$ polymer in pH 7.0 phosphate buffer at 25$^{\circ}$C. Desorption and reusability properties of the nanoparticles were investigated and lysozyme adsorption efficiency did not change significantly at the end of the 10 successive reuses.

    • Reversible papain immobilization onto poly(AAm–MMA)-based cryogels

      MURAT UYGUN RUKIYE YAVASER DENI Z AKTAS UYGUN

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      In the present work, new dye ligand affinity chromatographic support for papain adsorption was synthesized. For this purpose, poly(acrylamide–methyl methacrylate) [poly(AAm–MMA)] cryogels were synthesized by using the free radical cryopolymerization technique. These cryogels were then functionalized with Reactive Green 19 dye and were characterized with Fourier transform infrared, environmental scanning electron microscopy, macroporosityand energy-dispersiveX-ray spectrometer analyses. Incorporation of the dye molecule onto cryogel structure was clearly demonstrated by these characterization techniques and pore diameter of the cryogel was found to bearound 30–40 $\mu$m. Effects of medium pH, initial papain concentration, medium temperature and ionic strength on the papain adsorption onto dye-attached cryogel were also investigated. Maximum papain adsorption was found to be 40.66 mg g$^{−1}$ cryogel by using pH 5.5 acetate buffer at 25$^{\circ}$C. Reusability profile of the cryogel was also investigatedand it was found that the adsorption capacity of the cryogel decreased only about 2.13% at the end of the 10 reuses. Activity studies of papain in desorption medium were carried out and it was found that desorbed papain wasactive and showed 88.5% of its initial activity.

    • Metal-chelated cryogels for amyloglucosidase adsorption: application for continuous starch hydrolysis

      SINEM EVLI HANDE ORHAN PELIN SÖZEN AKTAS MURAT UYGUN DENIZ AKTAS UYGUN

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      In the present work, a newmetal-chelating platformwas designed by using IDA as a chelating agent and Cu(II) as an affinity component for amyloglucosidase adsorption. Poly(AAm-GMA) cryogels were used as structural elements, whileGMA monomer served reactive epoxy groups for IDA immobilization. Synthesized cryogels were characterized by FTIR, SEM and EDX studies. Pore diameter of the whole polymeric structure was 3–10 $\mu$m. Effects of medium pH, temperature,ionic strength along with amyloglucosidase concentrationwere also investigated for more effective amyloglucosidase adsorption and maximum adsorbed amount of amyloglucosidase was 2.93 mg g$^{−1}$ cryogel by the optimum conditions. Reusability profile of the poly(AAm-GMA)-IDA-Cu$^{2+}$ cryogels was also studied and it was found that the synthesized cryogels could be used repeatedly for many times without any significant decrease on their adsorption capacity. Also continuous hydrolysis of starch by using immobilized form of amyloglucosidase in a column system was studied.

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