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    Calixarene-immobilized monolithic cryogels for preparative protein chromatography
    (Elsevier B.V., 2018) Guven I.; Gezici O.; Bayrakci M.; Morbidelli M.
    New cation exchanger monolithic stationary phases were prepared by immobilization of three different calixarene derivatives (i.e. tetracarboxylate calix[4]arene, CLX-COO, tetrasulfonate calix[4]arene, CLX-SO3, and tetraphosphonate calix[4]arene, CLX-PO4) onto a monolithic cryogel support (i.e. poly(2-hydroksyethylmethacrilate-co-glycidyl methacrylate, P) and investigated with respect to preparative protein chromatography. The obtained monoliths were characterized through various techniques such as FTIR spectroscopy, isoelectric point measurements, titrimetric analyses, and mercury intrusion porosimetry. Protein retention was investigated using some model proteins (i.e. lysozyme, cytochrome c, and ?-chymotrypsinogen A, human serum albumin, and myoglobin), and the role of modifier (i.e. NaCl) concentration and pH was thoroughly analyzed under isocratic and gradient elution conditions. Overloading experiments were also conducted to study dynamic adsorption capacity and the obtained values were found to be ranging between 3 and 8 mg/mL depending on the type of calixarene molecule. Hence, higher or comparable protein adsorption capacities were seen to be applicable on calixarene-immobilized cryogels when compared to any other functionalized cryogels in the literature. Combined with the favorable properties of these monoliths, with respect to mass transport of large molecules, these results qualify calixarene functionalized monolithic cryogels as promising stationary phases for protein preparative purification. © 2018 Elsevier B.V.
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    Protein ion-exchange chromatography on a biomacromolecule-immobilized monolithic cryogel
    (TUBITAK, 2018) Özkan A.E.; Güven I.; Gezici O.
    An efficient and inexpensive monolithic stationary phase (PHEMA-HA) has been prepared through an easy process comprising addition of humic acid (HA) to a mixture of 2-hydroxyethyl methacrylate (HEMA) and N,N’-methylenebisacrylamide (MBAAm) and subsequent radical-polymerization at –20?C. The prepared monolithic material was characterized in terms of various techniques and methods such as elemental analysis, FTIR spectroscopy, scanning electron microscopy, mercury porosimetry, hydrolytic stability tests, pHpzc measurements, water-holding capacity, and water permeability. The amount of HA incorporated into the structure was calculated as 45 mg/g from the elemental analysis results. The study was conceptualized on the basis of protein ion-exchange chromatography, and some model proteins (i.e. a-chymotrypsinogen a, cytochrome c, lysozyme, human serum albumin, and myoglobin) were used in the chromatographic experiments. The effect of ionic strength and pH (5.0, 6.0, 7.0) on the retention behavior of proteins was investigated. The results revealed a typical ion-exchange behavior for the PHEMA-HA stationary phase, and with increasing gradient slope the model proteins were found to elute faster. Some model proteins could be separated by applying gradient elution where NaCl was used as the modifier. Dynamic adsorption capacity of PHEMA-HA was obtained by frontal analysis and was found as 4 mg/mL for Lys. © TÜBITAK.