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    Combined voltammetric and spectroscopic investigation of binding interaction between nifedipine and human serum albumin on polyelectrolyte modified ITO electrode
    (PERGAMON-ELSEVIER SCIENCE LTD, 2013) Ozmen, Mustafa; Maltas, Esra; Patir, Imren Hatay; Bayrakci, Mevlut
    The binding interaction between the drug molecule, nifedipine (Nf), and the human serum albumin (HSA) on polyelectrolyte modified indium tin oxide (ITO) electrode has been investigated by the combination of electrochemical and fluorescence spectroscopy techniques. Surface modification has also been characterized by scanning electron microscopy (SEM) and Contact Angle (CA) measurements in each step. The cyclic voltammetry, electrochemical impedance parameters (peak potential difference (Delta E-p)), peak current difference (Delta I-p) and charge-transfer resistance (R-ct) indicate that nifedipine strongly interacted with human serum albumin molecule on the polyelectrolyte modified ITO electrode surface. Stern-Volmer quenching constant K-a is inversely correlated with the temperature, which indicates that the probable quenching mechanism of the nifedipine-human serum albumin binding reaction is initiated by complex formation. The results obtained from these techniques showed that Nf could bind to HSA. The binding constant (K-b) and the number of binding sites (n) of the drug with HSA at different temperatures were determined. At 298 K, K-b was found as 4.04 x 10(-3) and n was 1.08 for Nf-HSA. According to the van't Hoff equation, the thermodynamic parameters, Delta G, Delta H and Delta S, were obtained, showing the involvement of hydrophobic and electrostatic force in this interaction. (C) 2013 Elsevier Ltd. All rights reserved.
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    Novel humic acid-bonded magnetite nanoparticles for protein immobilization
    (ELSEVIER SCIENCE BV, 2014) Bayrakci, Mevlut; Gezici, Orhan; Bas, San Zeki; Ozmen, Mustafa; Maltas, Esra
    The present paper is the first report that introduces (i) a useful methodology for chemical immobilization of humic acid (HA) to aminopropyltriethoxysilane-functionalized magnetite iron oxide nanoparticles (APS-MNPs) and (ii) human serum albumin (HSA) binding to the obtained material (HA-APS-MNPs). The newly prepared magnetite nanoparticle was characterized by using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and elemental analysis. Results indicated that surface modification of the bare magnetite nanoparticles (MNPs) with aminopropyltriethoxysilane (APS) and HA was successfully performed. The protein binding studies that were evaluated in batch mode exhibited that HA-APS-MNPs could be efficiently used as a substrate for the binding of HSA from aqueous solutions. Usually, recovery values higher than 90% were found to be feasible by HA-APS-MNPs, while that value was around 2% and 70% in the cases of MNPs and APS-MNPs, respectively. Hence, the capacity of MNPs was found to be significantly improved by immobilization of HA. Furthermore, thermal degradation of HA-APS-MNPs and HSA bonded HA-APS-MNPs was evaluated in terms of the Horowitz-Metzger equation in order to determine kinetic parameters for thermal decomposition. Activation energies calculated for HA-APS-MNPs (20.74 kJ mol(-1)) and HSA bonded HA-APS-MNPs (33.42 kJ mol(-1)) implied chemical immobilization of HA to APS-MNPs, and tight interactions between HA and HA-APS-MNPs. (C) 2014 Elsevier B.V. All rights reserved.
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    Synthesis and application of novel magnetite nanoparticle based azacrown ether for protein recognition
    (POLYMER SOC KOREA, 2013) Bayrakci, Mevlut; Maltas, Esra; Yigiter, Sengul; Ozmen, Mustafa
    This article is the first report showing the human serum albumin (HSA) binding studies by using a new magnetite nanoparticle containing azacrown ether moieties via solid-liquid extraction process. The structure of the newly prepared magnetite nanoparticle was clarified by using attenuated total reflectance (ATR) infrared spectroscopy, scanning electron microscopy (SEM), UV-vis and elemental analysis. Analytic results indicated that modification of the surface of the magnetite nanoparticles with azacrown ether derivative was successfully carried out. The protein binding studies exhibited that the modified magnetite nanoparticles could be efficiently used for the binding of the human serum albumin (HSA) in aqueous solutions via non-covalent interaction between crown ether cavity and amino group of the protein.