Browsing by Author "Avcibaşi N."

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    New thiophene-based azo ligands containing azo methine group in the main chain for the determination of copper(II) ions
    (2007) Dinçalp H.; Toker F.; Durucasu I.; Avcibaşi N.; Icli S.
    New kind of azo chromophores containing thiophene moiety and salicyaldimine-based ligand as side chains have been synthesized by a sequential process for optical sensing of Cu2+ metal ions in organic solution. Compounds have been characterized by IR and UV-vis spectrophotometer, 1H NMR, 13C NMR, MS, TGA and CV instruments. Spectral characteristics of the synthesized compounds have been investigated in five organic solvents of different polarity. Polarizibility effects of the solvents on the spectral characteristics and the dipole moments in the excited state are estimated. The fluorescence quantum yields of the synthesized compounds have been calculated to be in the range of 0.0035-0.0095 in solvents of different polarity. The fluorescence emission quenching experiments between the synthesized compounds and electron donor (pyrene, anthracene), electron acceptor (Co2+) compounds give the bimolecular quenching rate constants of 1011 and 1014 M-1 s-1, respectively. The free energies of photo-electron transfer process (ΔGET) between the azo dyes and the quenchers have been found to be about -19 kcal/mol. Cyclic voltammetry studies indicate that synthesized azo ligands undergo two- or three-reversible reduction potentials (versus ferrocene) and give LUMO energy value of -3.07 eV which is lower than that of TiO2 conduction band and has a band gap value of ∼2.5 eV. These results may point that synthesized azo dyes could be used as hole conducting materials in solid DSSC (Dye Sensitized Solar Cell) devices. Thermal decomposition behavior of the azo dyes gives more information about the structure of the studied materials. The photoisomerization behavior of the synthesized compounds has been investigated in ethyl acetate under Xe lamp irradiation in the fluorescence spectrophotometer for 1 h. Photoisomerization rate constants of cis-trans orientation (kc-t) have been found to be about 10-5 s-1. The complexation process of synthesized thienylidene azo dyes gives subtle changes in their absorption spectra. © 2006 Elsevier Ltd. All rights reserved.
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    Preliminary tests of the radiopharmaceutical potential of N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)-perylene-3,4,9,10-tetracarboxylic diimide radiolabeled with 131 I
    (Springer Netherlands, 2007) Avcıbaşı U.; Dinçalp H.; Ünak T.; Yıldırım Y.; Avcibaşi N.; Duman Y.; Içli S.
    Perylene diimide denvatives are one of the G-quadruplex DNA interactive agents which are thought to be useful in application of cancer treatment Starting from this consideration, N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)- perylene-3,4,9,10-tetracarboxylic diimide (PYPER) was synthesized, radioiodinated with 131 I, and its radiopharmaceutical potentials were tested on a male Albino rabbit and male Albino Wistar rats. This compound was successfully radioiodinated with 131 I with a radioiodination yield of about 100%. Scintigraphic imaging with the radiiodinated compound ( 131 I-PYPER) was performed on a rabbit. Static images were obtained from posterior projection using a Diacan gamma camera at several time intervals. The scintigrams clearly showed that the radioiodinated compound was not quickly cleared from the metabolism, accumulating in the stomach over about 30 minutes. The clearance time of this compound was considerably longer than 5 hours. The results obtained in this study agreed with that of the biodistribution studies and indicated that 131 I-PYPER might be used as a scintigraphic agent for examining stomach diseases. © 2007 Springer Science+Business Media, Inc.
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    Metabolic comparison of radiolabeled aniline- and phenol-phthaleins with 131I
    (2008) Avcibaşi U.; Avcibaşi N.; Ünak T.; Ünak P.; Müftüler F.Z.; Yildirim Y.; Dinçalp H.; Gümüşer F.G.; Dursun E.R.
    The metabolic comparison of aniline- and phenol-phthaleins radiolabeled with 131I (131I-APH and 131I-PPH, respectively) has been investigated in this study. To compare the metabolic behavior of these phthaleins and their glucuronide conjugates radiolabeled with 131I, scintigraphic and biodistributional techniques were applied using male Albino rabbits. The results obtained have shown that these compounds were successfully radioiodinated with a radioiodination yield of about 100%. Maximum uptakes of 131I-APH and 131I-PPH, which were metabolized as N- and O-glucuronides, were observed within 2 h in the bladder and in the small intestine, respectively. In the case of verification of considerably up taking of these compounds also by tumors developed in the small intestine and in the bladder tissues, these results can be expected to be encouraging to test these compounds, which will be radiolabeled with other radioiodines such as 125I, 123I and 124I as imaging and therapeutic agents in nuclear medical applications. © 2008 Elsevier Inc. All rights reserved.
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    Radiolabeling of new generation magnetic poly(HEMA-MAPA) nanoparticles with 131I and preliminary investigation of its radiopharmaceutical potential using albino Wistar rats
    (John Wiley and Sons Ltd, 2013) Avcibaşi U.; Demiroǧlu H.; Ediz M.; Akalin H.A.; Özçalişkan E.; Şenay H.; Türkcan C.; Özcan Y.; Akgöl S.; Avcibaşi N.
    In this study, N-methacryloyl-l-phenylalanine (MAPA) containing poly(2-hydroxyethylmethacrylate) (HEMA)-based magnetic poly(HEMA-MAPA) nanobeads [mag-poly(HEMA-MAPA)] were radiolabeled with 131I [ 131I-mag-poly(HEMA-MAPA)], and the radiopharmaceutical potential of 131I-mag-poly(HEMA-MAPA) was investigated. Quality control studies were carried out by radiochromatographic method to be sure that 131I binded to mag-poly(HEMA-MAPA) efficiently. In this sense, binding yield of 131I-mag-poly(HEMA-MAPA) was found to be about 95-100%. In addition to this, optimum radiodination conditions for 131I-mag-poly(HEMA- MAPA) were determined by thin-layer radiochromatography studies. In addition to thin-layer radiochromatography studies, lipophilicity (partition coefficient) and stability studies for 131I-mag-poly(HEMA-MAPA) were realized. It was determined that lipophilicities of mag-poly(HEMA-MAPA) and 131I-mag-poly(HEMA-MAPA) were 0.12 ± 0.01 and 1.79 ± 0.76 according to ACD/logP algorithm program, respectively. Stability of the radiolabeled compound was investigated in time intervals given as 0, 30, 60, 180, and 1440 min. It was found that 131I-mag-poly(HEMA-MAPA) existed as a stable complex in rat serum within 60 min. After that, biodistribution and scintigraphy studies were carried out by using albino Wistar rats. It was determined that the most important 131I activity uptake was observed in the breast, the ovary, and the pancreas. Scintigraphy studies well supported biodistribution results. Copyright © 2013 John Wiley & Sons, Ltd.
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    Synthesis and biodistribution of novel magnetic-poly(HEMA-APH) nanopolymer radiolabeled with iodine-131 and investigation its fate in vivo for cancer therapy
    (Kluwer Academic Publishers, 2013) Avcibaşi U.; Avcibaşi N.; Akalin H.A.; Ediz M.; Demiroǧlu H.; Gümüşer F.G.; Özçalişkan E.; Türkcan C.; Uygun D.A.; Akgöl S.
    Herein, we investigated the biological uptake, distribution, and radiopharmaceutical potential of a novel molecule based on 2-hydroxyethyl methacrylate (HEMA) and anilinephtalein (APH) in the metabolism of Albino Wistar rats. In order to achieve this, we synthesized APH using organic synthesis methods and copolymerized APH with HEMA using a common polymerization method, surfactant-free emulsion polymerization. In the presence of Fe3O 4 particles, we obtained a new generation magnetic-nano-scale polymer, magnetic-poly(HEMA-APH). This new molecule was chemically identified and approved by several characterization methods using Fourier transform infrared spectroscopy, scanning electron microscope, energy dispersive X-ray spectroscopy, electron spin resonance, atomic force microscope, and Zeta particle-size analysis. To evaluate the biological activity in live metabolism and anti-cancer potential of mag-poly(HEMA-APH), molecule was radioiodinated by a widely used labeling technique, iodogen method, with a gamma diffuser radionuclide, 131I. Thin-layer radiochromatography experiments demonstrated that 131I binded to nanopolymer with the labeling yield of 90 %. Lipophilicity and stability experiments were conducted to determine the condition of cold and labeled mag-poly(HEMA-APH) in rat blood and lipid medium. Results demonstrated that radioiodinated molecule stayed as an intact complex in rat metabolism for 24 h and experimental lipophilicity was determined as 0.12 ± 0.02. In vivo results obtained by imaging and biological distribution experiments indicated that mag-poly(HEMA-APH) labeled with 131I [131I-mag-poly(HEMA-APH)] highly incorporated into tissues of the uterus, the ovarian, the prostate, and the lungs in rat metabolism. Based on these results, it may be evaluated that novel mag-poly(HEMA-APH) molecule labeled with 131I is a compound which has a significant potential for being used as an anti-cancer agent. Certain results can only be obtained whether this molecule is applied to adenocarcinoma cell models and tumor-bearing animals. © 2013 Springer Science+Business Media Dordrecht.
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    Hydrophobic nano-carrier for lysozyme adsorption
    (Indian Academy of Sciences, 2016) Altunbaş C.; Ural F.Z.; Uygun M.; Avcibaşi N.; Avcibaşi U.; Uygun D.A.; Akgol S.
    In this work, poly(HEMA-APH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique. Magnetic behaviour was introduced by simple addition of Fe3O4 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 were optimized and maximum lysozyme binding capacity was found to be 278.8 mg g-1 polymer in pH 7.0 phosphate buffer at 25°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. © 2016 Indian Academy of Sciences.