Yazar "Andac, Muge" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • [ X ]
    Öğe
    Cadmium removal out of human plasma using ion-imprinted beads in a magnetic column
    (Elsevier, 2009) Candan, Nilgun; Tuzmen, Nalan; Andac, Muge; Andac, Cenk A.; Say, Ridvan; Denizli, Adil
    The aim of this study is to utilize ion-imprinted magnetic beads in the selective removal of Cd2+ ions out of human plasma overdosed with Cd2+ ions. The Cd (2+) imprinted magnetic poly(HEMA-MAC) (mPHEMAC-Cd2+) beads were produced by suspension polymerization in the presence of magnetite Fe3O4 in a nano-powder form. The template Cd2+ ions could be reversibly detached from the matrix to form mPHEMAC-Cd2+ beads using 0.1 M thiourea solution. The specific surface area of the mPHEMAC-Cd2+ beads was found to be 24.7 m(2)/g. The MAC and Fe3O4 contents of the mPHEMAC-Cd2+ beads were found to be 41.8 mu mol/g polymer and 8.2% on the average. The Cd2+ adsorption capacity of mPHEMAC-Cd2+ columns decreased drastically from 48.8 mu mol/g to 20.0 mu mol/g as the flow rate is increased from 0.50 ml/min to 3.0 ml/min. The maximum adsorption capacity of the mPHEMAC-Cd2+ beads was determined to be 48.8 mu mol Cd2+/g on the average. The relative selectivity coefficients of the mPHEMAC beads for Cd2+/Pb2+ and Cd2+/Zn2+ were 22.6 and 160.7 times greater than those of the non-imprinted magnetic PHEMAC (mPHEMAC) beads, respectively. The mPHEMAC-Cd2+ beads are reusable for many times with no significant decrease in their adsorption capacities. (C) 2008 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    Molecular Recognition-Based Detoxification of Aluminum in Human Plasma
    (Taylor & Francis Ltd, 2009) Demircelik, Ahmet H.; Andac, Muge; Andac, Cenk A.; Say, Ridvan; Denizli, Adil
    Molecular recognition-based Al3+-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-L-glutamic acid) (PHEMAGA-Al3+) beads were prepared to be used in selective removal of Al3+ out of human plasma overdosed with Al3+ cations. The PHEMAGA-Al3+ beads were synthesized by suspension polymerization in the presence of a template-monomer complex (MAGA-Al3+). The specific surface area of PHEMAGA-Al3+ beads was found to be 55.6 m(2)/g on the average. The MAGA content in the PHEMAGA-Al3+ beads were found to be 640 mu mol/g polymer. The template Al3+ cations could be reversibly detached from the matrix to form PHEMAGA-Al3+ using a 50 mM solution of EDTA. The Al3+-free PHEMAGA-Al3+ beads were then exposed to a selective separation procedure of Al3+ out of human plasma, which was implemented in a continuous system by packing the beads into a separation column (10 cm long with an inner diameter of 0.9 cm) equipped with a water jacket to control the temperature. The Al3+ adsorption capacity of the PHEMAGA-Al3+ beads decreased drastically from 0.76 mg/g polymer to 0.22 mg/g polymer as the flow rate was increased from 0.3 ml/min to 1.5 ml/min. The relative selectivity coefficients of the PHEMAGA-Al3+ beads for Al3+/Fe3+, Al3+/Cu2+ and Al3+/Zn2+ were found to be 4.49, 8.95 and 32.44 times greater than those of the non-imprinted PHEMAGA beads, respectively. FT-IR analyses on the synthesized PHEMAGA-Al3+ beads reveals monodentate and bidentate binding modes of Al3+ in complex with the carboxylate groups of the glutamate residues. Density functional theory computations at the B3LYP/6-31G(d,p) basis set suggests that structured water molecules play essential role in the stability of the monodentate binding mode in 1:1 PHEMAGA-Al3+ complexes. The PHEMAGA-Al3+ beads were recovered and reused many times, with no significant decrease in their adsorption capacities. (C) Koninklijke Brill NV, Leiden, 2009
  • [ X ]
    Öğe
    Predicting the binding properties of cibacron blue F3GA in affinity separation systems
    (Elsevier, 2007) Andac, Cenk A.; Andac, Muge; Denizli, Adil
    The binding properties of cibacron blue F3GA (CB-F3GA) bound to a model NAD(P)H/FAD(H-2)-dependent protein system, namely cytosolic quinone reductase (QR), was characterized by AMBER in an attempt to address the binding properties of immobilized CB-F3GA used in the separation of serum albumin. A favorable binding free energy of -4.52 kcal/mol (K-D = 5.09 x 10(-4) kcal/mol) was determined for CB-F3GA binding by MM-PBSA method, which was found to be a ballpark estimate of empirical values reported in literature (Delta G approximate to -6 kcal/mol). We propose that CB-F3GA primarily follows a class III binding motif in presence of FAD in the binding site of QR in solution, while a class II binding motif is observed in the crystal form. It was found that favorable van der Waals/hydrophobic interactions take place in the binding site making a major contribution to a favorably dominating enthalpy of binding (Delta H-tot = -25.87 kcal/mol) as compared to a disfavorable binding entropy term (T Delta S-tot = -21.35 kcal/mol). Additional MM-PBSA experiments in the absence of FAD gave rise to a disfavorable binding free energy for CB in complex with QR, suggesting that FAD is an essential determinant of CB-F3GA binding. This is in contrast to an earlier observation of Denizli et al. on separation of human serum albumin (HSA) by immobilized CB-F3GA in the absence of FAD. Therefore, a class I binding model for CB-F3GA is proposed here to account for the efficient separation of HSA in affinity chromatography systems. (C) 2007 Elsevier B.V. All rights reserved.