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Öğe An Application of a Schiff-Base Type Reaction in the Synthesis of a New Rhodamine-Based Hg(II)-Sensing Agent (vol 29, pg 1349, 2019)(Springer/Plenum Publishers, 2020) Çiçekbilek, Fulya; Altınok, Bahar Yılmaz; Bayrakcı, Mevlüt; Gezici, Orhan[Abstract Not Available]Öğe An application of polydopamine-dip coating as a gentle surface modification process for cryogel disks(2020) Özbek, Gözde; Gezici, Orhan; Bayrakcı, MevlütThe process called “polydopamine-dip coating” was successfully applied to modify the surface of poly(2-hydroxyethyl methacrylate), PHEMA, cryogel disks for the first time. This facile surface modification process fitted very well to the chemistry of cryogels since the integrity of the cryogel disks was maintained during the whole process. Polydopamine (PDA) nanocoating process was observed to be homogeneously performed through the pores and there was a net color change from white to brown after 24 h. The obtained (brownish) material (PHEMA-PDA) was characterized with respect to FTIR spectroscopy, pHpzc, and water-holding capacity analyses. The potential of this new material was studied by utilizing it as an adsorbent for the adsorption of Ni(II) from synthetic aqueous solutions. The equilibrium adsorption data were analyzed on the basis of the Langmuir, the Freundlich, and the Temkin isotherm models. In general, Ni(II) adsorption on PHEMA-PDA was evaluated as a favorable process as depicted from the studied models. The proposed approach was found to be a promising post- surface modification process for tailoring the surface of monolithic cryogels without any difficult synthesis steps and harsh chemicals.Öğe An application of a schiff-base type reaction in the synthesis of a new rhodamine-based hg(II)-sensing agent(Springer / Plenum Publishers) Çiçekbilek, Fulya; Yılmaz, Bahar; Bayrakcı, Mevlüt; Gezici, OrhanA facile synthesis procedure, whereby 9-Anthraldehyde (AA) is coupled to aminated rhodamine (AR) via a Schiff base-type reaction, is reported. The applicability and performance of the obtained material (AA-AR) as a sensing agent was studied towards 16 metal cations (i.e. Li+, Na+, Ag+, Ca2+, Ba2+, Co2+, Cs+, Cu2+, Mg2+, Hg2+, Mn2+, Pb2+, Ni2+, Sr2+, Zn2+, Al3+). Among the studied metals, an extraordinary selectivity was observed for Hg2+, and the observed selectivity was found not to be influenced by the presence of other cations and some common anions (i.e. Br-, Cl-, I-, HPO42-, H2PO4-, NO3-, NO2-, ClO4-, AcO-, HSO4-, SO42-, Cr2O7-, CO32-, OH- and HCO3-). The material, AA-AR, exhibited such a high selectivity and sensitivity towards Hg2+ that it could be detected even by naked eyes. The Hg2+-sensing property of AA-AR was found not to be limited to colorimetric detections so that a high fluorescent nature of the compound was also observed upon binding Hg2+ ion. The detection limit, which is correspondent to fluorescence emission intensity, was found as 0.87 mu M. The underlying mechanism of sensing property was studied by using some spectroscopic techniques such as FT-IR, H-1-NMR, C-13-NMR, and UV-Vis. (Job-plot). In the final course of the experiments, the performance of AA-AR in cell-imaging was also studied, and even trace amounts of Hg2+ in living cells could be detected by the studied probe. Thus, the applicability of a new synthesis approach in producing a highly efficient new fluorescence sensor for the detection of Hg2+ ions is discussed in detail.Öğe Calixarene-engineered surfaces and separation science(Springer, 2015) Gezici, Orhan; Bayrakcı, MevlütAfter their discovery, calixarenes have attracted the attention of many researchers from various disciplines. This group of supramolecules has an increasing popularity and this is most probably related with the flexibility of calixarene chemistry. Owing to their multifunctional character and stability, calixarenes became important precursors in separation science to derive new-type of sorbents or stationary phases. Immobilization of calixarenes to a suitable solid support (e.g. silica, synthetic polymers, magnetite nanoparticles, etc.) is a very popular concept being used for this purpose, and various immobilization methodologies have been proposed in the literature. In the present work, some state-of-the-art researches and developments published in the past are reviewed in a collective manner, and thus fundamentals of calixarene-immobilization and the application of the obtained materials in sorption and high performance liquid chromatography are represented.Öğe Calixarene-immobilized monolithic cryogels for preparative protein chromatography(Elsevier Science Bv, 2018) Güven, İdris; Gezici, Orhan; Bayrakcı, Mevlüt; Morbidelli, MassimoNew 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 alpha-chymotrypsinogen A, human serum albumin, and myoglobin), and the role of modifier (i.e. NaCI) 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. (C) 2018 Elsevier B.V. All rights reserved.Öğe Correction to: An Application of a Schiff-Base Type Reaction in the Synthesis of a New Rhodamine-Based Hg(II)-Sensing Agent (Journal of Fluorescence, (2019), 29, 6, (1349-1358), 10.1007/s10895-019-02462-5)(Springer, 2020) Cicekbilek, Fulya; Yilmaz, Bahar; Bayrakci, Mevlut; Gezici, OrhanThe original version of this article unfortunately contained a mistake. The presentation of Scheme 1 was incorrect as the word "modifified" should be written as "modified" and the abbreviation "CS-F" should be replaced by "AA-AR". The corrected scheme is given below. Scheme 1 A schematic view for the synthesis of AA-AR probe (Figure Presented.). © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Öğe Humic-makeup approach for simultaneous functionalization of polyacrylonitrile nanofibers during electrospinning process, and dye adsorption study(Taylor & Francis INC, 2016) Gezici, Orhan; Güven, İdris; Özcan, Fatih; Ertül, Şeref; Bayrakcı, MevlütA useful methodology is represented to functionalize polyacrylonitrile nanofibers by using humic acid as a makeup agent in electrospinning process. Both morphology and surface chemistry of polyacrylonitrile nanofiber mats were understood to be influenced by incorporation of humic acid into the structure. Physicochemical changes were evidenced by Fourier transform infrared spectroscopy, scanning electron microscope, and surface charge measurements. Unlike some anionic dyes (i.e., methyl orange, methyl red, and Congo red), there was an enhancement in crystal violet (a cationic dye) adsorption after incorporation of humic acid. The Langmuir model fitted well to crystal violet data, and monolayer adsorption capacity was calculated as 81.6 mg/g (r(2) = 0.998).
