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Öğe Biocompatible thermoresponsive PEGMA nanoparticles crosslinked with cleavable disulfide based crosslinker for dual drug release(AMER CHEMICAL SOC, 2014) Ulasan, Mehmet; Yavuz, Emine; Bagriacik, Emin Umit; Cengeloglu, Yunus; Yavuz, Mustafa Selman[Abstract not Available]Öğe Biocompatible thermoresponsive PEGMA nanoparticles crosslinked with cleavable disulfide-based crosslinker for dual drug release(WILEY, 2015) Ulasan, Mehmet; Yavuz, Emine; Bagriacik, Emin Umit; Cengeloglu, Yunus; Yavuz, Mustafa SelmanSmart materials have been attracting much attention because of their stimuli responsive nature. We have synthesized biocompatible thermoresponsive crosslinked poly(ethylene glycol) methyl ether methacrylate (PEGMA)-co-vinyl pyrrolidone nanoparticles (PEGMA NPs) using disulfide-based crosslinker by surfactant-free emulsion polymerization method. Particle characterization studies were carried out by dynamic light scattering, and scanning electron microscopy. Polymerization kinetics, effect of crosslinker and initiator concentrations on both average hydrodynamic diameter and polydispersity index were investigated. Hydrodynamic diameters of thermoresponsive PEGMA NPs were decreased from 210 nm to 90 nm upon heating over the lowest critical solution temperature (LCST). Disulfide crosslinked PEGMA NPs were demonstrated as a dual delivery system. Rhodamine B, a model of small-sized drug molecule, and poly(ethylene glycol) (PEG)-alizarin yellow, a model of large drug molecule, were loaded into PEGMA NPs where LCST of these NPs was tuned to 37 degrees C, the body temperature. The rhodamine B was released from PEGMA NPs upon heating to 39 degrees C. Then, PEG-alizarin content was released by subsequent degradation of nanoparticles using dithiothreitol (DTT), which reduces disulfide bonds to thiols. Furthermore, cytotoxicity studies of PEGMA NPs were carried out in 3T3 cells, which resulted in no toxic effect on the cells. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 243-251, 2015.Öğe Electrocapillary Curves for the Polarisable Liquid-Liquid Interface in Presence of the Peptide Melittin(WALTER DE GRUYTER GMBH, 2016) Uyanik, Ibrahim; Cengeloglu, YunusThe adsorption of the anti-microbial peptide melittin at the polarisable water/1,2-DCE (W-DCE) interface is expected to manifest itself by changes in the interfacial tension. These interfacial tension changes during the peptide adsorption at the interface were measured by a custom-built quasi-elastic light scattering (QELS) setup. Electrocapillary curves obtained for melittin at physiological pH evidences the strong affinity of this peptide for the W-DCE interface. In other words, it is evident that at negative potentials the peptide are readily adsorbed and that at more positive potentials desorption of adsorbed peptide from the interface proceeds leading to an increase of interfacial tension.Öğe Electrodialytic removal of fluoride from water: Effects of process parameters and accompanying anions(ELSEVIER, 2008) Ergun, Erdem; Tor, Ali; Cengeloglu, Yunus; Kocak, IzzetThe removal of fluoride from water by using electrodialysis with SB-6407 anion exchange membrane was tested at different current densities. After the determination of the optimum pH of feed phase under Donnan dialysis condition which gave the maximum transport of fluoride, the effect of mono- and bi-valent ions, such as chloride and sulphate, in the feed phase on the removal was investigated by electrodialysis. The transport of fluoride was also correlated with the flux data and explained according to structure of membrane. It was found that the removal of fluoride was higher in the absence of mono- and bi-valent ions. The reducing effect of sulphate ions on the transport of fluoride was higher than that of chloride ions, which was explained by considering interaction of both chloride and sulphate ions with the ionic group in the membrane and activity coefficient of fluoride in the presence of mono- and bi-valent ion set. Moreover, transport of fluoride increased with increasing current density and feed phase concentration. As the driving ion, the chloride ion is more efficient than the sulfate ion. Application of electrodialysis was carried out on the real water containing 20.6 mg/L of fluoride. Despite the presence of chloride and sulphate in real water sample, fluoride concentration could be reduced to 0.8 mg/L (96% removal), which was lower than World Health Organization (WHO) standard (1.5 mg/L. (C) 2008 Elsevier B.V. All rights reserved.Öğe Facile synthesis of boronic acid-functionalized nanocarriers for glucose-triggered caffeic acid release(SPRINGER, 2015) Ulasan, Mehmet; Yavuz, Emine; Cengeloglu, Yunus; Yavuz, Mustafa SelmanIn this study, boronic acid-functionalized methacrylate-based nanoparticles were synthesized via surfactant-free emulsion polymerization in one pot. Uniform (polydispersity index < 0.05) sub-100 nm nanoparticles were obtained. The changes of average hydrodynamic diameter and polydispersity index of nanoparticles against boronic acid content in total monomer and acetone percentage in the solvent mixture were investigated. Polymerization kinetics in terms of monomer conversion rate was monitored by gravimetric method. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. The boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. Further, the nanoparticles were combined with caffeic acid. Caffeic acid carrying nanoparticles were titrated against glucose or fructose in which caffeic acid is released by the displacement reaction in a controlled manner. The displacement of caffeic acid and glucose was monitored by UV-visible spectral change. Furthermore, in vitro biocompatibility of nanoparticles was tested in NIH-3T3 cells, which resulted no significant toxicity effect on the cells.Öğe Removal of boron from water by using reverse osmosis(ELSEVIER SCIENCE BV, 2008) Cengeloglu, Yunus; Arslan, Gulsin; Tor, Ali; Kocak, Izzet; Dursun, NesimThe removal of boron from water was investigated by using reverse osmosis (110) technique with SWHR, BW-30 (FILMTEC) and AG (GE Osmonics) membranes, not considered :previously. The effect of pH and concentration of the feed water and operating pressure on the boron rejection was investigated. The experimental results indicated that boron rejection mostly depends on membrane type, pH of the feed water and operating pressure. The results also showed that boron car. be effectively removed only at feed water pH of 11. The lowest permeate boron concentration (the highest rejection, close to 99%) was obtained when SWHR membrane was used. The rejection efficiency of the membranes was found to be in the order of SWHR > BW-30 > AG. For all membranes, boron rejection increased with increasing operating pressure. Finally, two different natural (ground) water samples containing 24.8 and 9.4 mg/L of boron were treated by using RO with SWHR membrane and obtained results showed that RO could be efficiently used (with >95% rejection) for removal of boron from groundwaters. (C) 2008 Elsevier B.V. All rights reserved.Öğe Removal of congo red from aqueous solution by adsorption onto acid activated red mud(ELSEVIER SCIENCE BV, 2006) Tor, Ali; Cengeloglu, YunusThe objective of this study is to remove the congo red (CR) anionic dye, from water by using the acid activated red mud in batch adsorption experiments. The effects of contact time, pH, adsorbent dosage and initial dye concentration on the adsorption were investigated. The pH of the dye solution strongly affected the chemistry of both the dye molecules and activated red mud in an aqueous solution. The effective pH was 7.0 for adsorption on activated red mud. It was found that the sufficient time to attain equilibrium was 90 min. The adsorption isotherms were analyzed using the Langmuir, the Freundlich, and the three parameter Redlich-Peterson isotherms. The Langmuir isotherm was the best-fit adsorption isotherm model for the experimental data obtained from the non-linear chi-square statistic test. (c) 2006 Elsevier B.V. All rights reserved.Öğe Removal of fluoride from water by using granular red mud: Batch and column studies(ELSEVIER, 2009) Tor, Ali; Danaoglu, Nadide; Arslan, Gulsin; Cengeloglu, YunusThis paper describes the removal of fluoride from water using granular red mud (GRM) according to batch and column adsorption techniques. For the batch technique, the experiments demonstrated that maximum fluoride removal was obtained at a pH of 4.7 and it took 6 h to attain equilibrium and equilibrium time did not depend upon the initial fluoride concentration. Kinetics data were fitted with pseudo-second-order model. The Redlich-Peterson and Freundlich isotherm models better represented the adsorption data in comparison to the Langmuir model. Column experiments were carried out under a constant influent concentration and bed depth, and different flow rates. The capacities of the breakthrough and exhaustion points decreased with increase of the flow rate. Thomas model was applied to the experimental results. The modelled breakthrough curves were obtained, and they were in agreement with the corresponding experimental data. The column adsorption was reversal and the regeneration operation was accomplished by pumping 0.2 M of NaOH through the loaded GRM-column. (C) 2008 Elsevier B.V. All rights reserved.Öğe Removal of Rhodamine B from water by using CdTeSe quantum dot-cellulose membrane composites(ROYAL SOC CHEMISTRY, 2016) Baslak, Canan; Arslan, Gulsin; Kus, Mahmut; Cengeloglu, YunusFacilitated transport of Rhodamine B through a novel polymer inclusion membrane (PIM) containing CdTeSe Quantum Dots (QDs) as a carrier reagent has been investigated. The prepared PIM was characterized with Fourier transform infrared (FT-IR) spectroscopy, Atomic Force Microscopy (AFM), confocal microscopy, X-ray Photoelectron Spectroscopy (XPS) and fluorescence spectroscopy (PL) techniques and contact angle measurements. The transport was observed by the increased absorbance peak of the stripping phase by UV-visible and fluorescence spectrophotometer. The transport efficiency of Rhodamine B was observed to be 60% after 6 h under optimized conditions. When the feed phase contained 0.005% Rhodamine B at pH 12.19, Rhodamine B was transported through the PIM (prepared with 0.1% CdTeSe QDs) by using 1 M HCl as a stripping phase. The results also showed that the transport efficiency of the PIM was reproducible and it could be beneficial in long-term separation processes.Öğe Synthesis of biocompatible thermoresponsive PEGMA nanoparticles for dual release(AMER CHEMICAL SOC, 2015) Yavuz, Emine; Ulasan, Mehmet; Cavusoglu, Halit; Cengeloglu, Yunus; Yavuz, Mustafa Selman[Abstract not Available]
