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Öğe Bioremoval of mercury (II) from aqueous solutions by Phragmites australis: Kinetic and equilibrium studies(Taylor & Francis Inc, 2018) Kankilic, Gokben Basaran; Metin, Aysegul Ulku; Aluc, Yasar; Bozkaya, OgunIn this study, the removal of mercury (II) ions from aqueous solutions by dried biomass of Phragmites australis was investigated in the batch system. The biomass was characterized by Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray fluorescence (ED-XRF), Brunauer-Emmett-Teller (BET) surface area techniques (BET). Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP-OES, Spectro Blue) was used to analyze Hg(II) concentration and obtained data in batch experiments indicated that Hg (II) was rapidly adsorbed and such adsorption reached equilibrium within 60 min. The initial pH of the solution was effective parameter for Hg (II) biosorption. The biosorption kinetics was in better good fit with pseudo-second order kinetics and the results obtained from the batch experiments were conformed better with the Langmuir isotherm model than Freundlich and D-R isotherm models. The maximum Hg (II) biosorption capacity of P. australis was 20.0 +/- 0.4mg/g. The availability of other metal ions affected mercury biosorption. Adsorption/desorption studies demonstrated that the adsorbed Hg (II) could be desorbed effectively with a 0.1M ethylenediamine tetra-acetic acid (EDTA) solution. The biosorption capacity of the regenerated biosorbent could still be maintained at 72% at the fifth adsorption-desorption cycle. Consequently, it can be said that P. australis can be used as an applicable, cost-efficient, nature friendly biosorbent for treating wastewater. [GRAPHICS] .Öğe Elimination of carcinogenic bromate ions from aqueous environment with 4-vinyl pyridine-g-poly(ethylene terephthalate) fibers(Springer Heidelberg, 2019) Gunay, Kubra; Arslan, Metin; Bozkaya, Ogun; Aluc, Yasar; Gok, Zehra GunIn this study, poly(ethylene terephthalate) fibers grafted with 4-vinyl pyridine (PET-g-4VP) was synthesized with using a radical polymerization method and its removal capacity for bromate ions in the aqueous solution was explored. The synthesized graft copolymer was structurally characterized by scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). The effect of some parameters such as pH, grafting rate, processing time, and ion concentration on bromate removal was examined with batch experiments. The sorptions of bromate onto the PET-g-4VP fibers were both verified with FTIR and X-ray fluorescence analysis (XRF) and the remaining amount of bromate after adsorption process was determined with an ion chromatography (Shimadzu). Moreover, kinetic and isotherm studies were also performed for adsorption of bromate with the grafted fibers. The point of zero charge (pH(pzc)) of the PET-g-4VP fibers was found to be 7.5 and the fibers removed maximum amount of bromate from aqueous solution at pH 3. Equilibrium time of adsorption was determined to be 75 min and the adsorption kinetic was found to be pseudo-second-order model. It was observed that the increase in the amount of grafted 4VP onto the PET fibers increased the bromate removal capacity of the fibers; however, when the grafting yield of 4VP was over 80%, the bromate removal ability of the fibers decreased. The maximum bromate removal capacity of the PET-g-4VP was determined to be 183 mg/g when the initial bromate amount was 800 mg/L, treatment time was 75 min, pH of the solution was 3, and 4VP grafting yield was 80%. When the initial bromate concentration was higher than 800 mg/L, the removal rate of the PET-g-4VP fibers was not changed. In addition, bromate ion adsorption data indicated compliance with the Freundlich isotherm. The adsorbent fibers obtained by this study may be promising candidates for the removal of bromate ions from the aqueous media.Öğe Evaluation of Burn Wound Healing Efficacy and Biocompatibility of Centella asiatica Mediated Synthesised AgNPs Loaded Hybrid Nanofiber Scaffold: In Vitro and In Vivo Studies(Wiley-V C H Verlag Gmbh, 2024) Bozkaya, Ogun; Bozkaya, Esra; Ekici, Husamettin; Alcigir, Mehmet Eray; Sahin, Yasar; Cerci, Nebahat Aytuna; Karahan, SiyamiThe aim of this study is to evaluate the cell responses, potential skin reactions during the treatment process and burn wound healing efficacy of electrospun polycaprolactone/polyethylene oxide (PCL/PEO) nanofibers (NFs) containing Centella asiatica mediated synthesized silver nanoparticles (CA-AgNPs) by in vitro and in vivo studies. Apoptosis-necrosis, genotoxicity, hemolysis, and cell attachment studies are carried out within the scope of in vitro tests, and irritation, sensitivity, and burn wound studies are carried out within the scope of in vivo tests. The apoptotic index value of CA-AgNPs-[PCL/PEO] NFs material on L929 fibroblast cells is determined as 5.0 +/- 1.0% at the highest concentration and the necrotic index value is 5.0 +/- 0.3%. Micronucleus rates (%) of NFs treated with CHO (Chinese Hamster Ovary) cells are not at genotoxic level. The hemolytic index value of NFs dressing is determined as 0.23 +/- 0.03%, The primary irritation index (PII) value of NFs wound dressing is calculated as 0.36 by irritation tests. In addition, the potential sensitization reaction of NFs extract on guinea pigs is evaluated and the sensitization score is determined as 0.9. The healing efficacy of NFs material on second-degree burn wounds compared to a commercial product is supported by pathomorphological findings.Öğe In situ synthesis of silver nanoparticles on modified poly(ethylene terephthalate) fibers by grafting for obtaining versatile antimicrobial materials(SPRINGER, 2020) Gun Gok, Zehra; Demiral, Ayse; Bozkaya, Ogun; Yigitoglu, MustafaBecause of having high mechanical properties and cheapness of PET textiles, functionalization of them for new properties is an active research area. In the present work, methacrylic acid (MAA)-grafted PET fibers (PET-g-MAA) were obtained by grafting of MAA monomers to PET surface for an antimicrobial material synthesis. The morphologies of the obtained graft copolymers were examined with a scanning electron microscopy (SEM), and the chemical modification after grafting was determined with Fourier-transform infrared spectroscopy (FTIR) analysis. Subsequently, silver ions were adsorbed onto the PET-g-MAA fibers surface and the adsorbed ions to the surface were reduced to silver nanoparticles (AgNPs) by UVC light. The morphology of fiber surfaces modified with MAA and coated with AgNPs was examined by SEM studies, and it was observed that AgNPs were disturbed along the fibers. The presence of silver on the surface was also confirmed by energy-dispersive X-ray spectroscopy (EDS) and energy dispersion X-ray fluorescence spectrometry (EDXRF). The crystalline structure of the original PET fiber, PET-g-MAA fiber and PET-g-MAA fiber modified with AgNPs was investigated by X-ray diffraction (XRD). The thermal properties of the obtained fibers were investigated by thermogravimetric analysis (TGA). The immobilization of AgNPs on the grafted fibers leads to a change on the patterns of TGA curves. The most significant change is the less weight reduction in the temperature range of 200-300 degrees C. Disk diffusion test was performed using Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25,922) bacteria in order to investigate the antibacterial ability of the obtained fibers, and it was found that the fibers coated with AgNPs had antibacterial effect on both bacterial species. The cytotoxicity of the groups with the best antibacterial properties was determined by MTT test, and the synthesized material did not have cytotoxic effects on L929 fibroblast cells. The material obtained has the potential to be used in antimicrobial applications.Öğe Investigation of the biological activity and toxicity of bioactive silver nanoparticles synthesized via Vitex agnus-castus seed extract on honey bees(Springer, 2024) Ekici, Seda; Bozkaya, Ogun; Sevin, Sedat; Erdem, Babur; Arslan, Okan Can; Cinar, Ozge Ozgenc; Bozkaya, EsraIn this study, silver nanoparticles (AgNPs) coated with bioactive molecules were synthesized via Vitex agnus-castus L. (VAC) seed extract (VAC/AgNPs). The synthesized VAC/AgNPs were characterized by surface plasmon resonance (SPR) ultraviolet-visible region spectroscopy (UV-Vis). The hydrodynamic size and surface charge analysis of the particles were measured with a Zeta sizer. The results of UV-Vis and Zeta analysis revealed that AgNPs were synthesized, the size distribution was nanoscale, and the solution was stable. The effects of the synthesized VAC/AgNPs and aqueous extract of VAC seeds on honeybees were investigated by means of lifespan test and histopathological analysis. It was determined that both VAC seed extract and VAC/AgNPs were non-toxic to honeybees at certain doses, positively affected their life span and contributed to their longevity in the life span test. Furthermore, no adverse effects were detected in terms of intestinal health in histopathological examinations. Therefore, VAC/AgNPs are considered to be a promising bioactive agent for honeybees.Öğe Investigation of the in vitro antibacterial, cytotoxic and in vivo analgesic effects of silver nanoparticles coated with Centella asiatica plant extract(Ankara Univ, 2023) Bozkaya, Ogun; Ekici, Husamettin; Gun Gok, Zehra; Arat, Esra; Ekici, Seda; Yigitoglu, Mustafa; Vargel, IbrahimIn recent years, researchers have shown an increased interest in using medicinal plants for the synthesis of silver nanoparticles (AgNPs) having various therapeutic properties. Centella asiatica (CA), a medicinal plant, has been used to treat minor burn wounds, psoriasis, and hypertrophic wounds among many other pathological conditions. The current study aimed to synthesize CA coated AgNPs (CA-AgNPs) with appropriate biocompatibility and various therapeutic properties, including antimicrobial and analgesic activities. The synthesized CA-AgNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, zeta potential measurements, and fourier transform infrared (FT-IR) spectroscopy. The formation of spherical CA-AgNPs was confirmed by a single surface plasmon resonance (SPR) peak emerging at 420 nm wavelength by UV-Vis. The average hydrodynamic diameter and zeta potential of the particles were found to be 29.5 nm and -24.5 mV, respectively. The FT-IR analyses showed that the AgNPs were coated and stabilized by bioactive compounds from the CA extract. MTT cytotoxicity assay revealed that CA-AgNPs at <= 1 mM concentrations exhibited biocompatibility for L929 fibroblast cells. The antimicrobial activity of CA-AgNPs was confirmed by significant inhibition of Staphylococcus aureus and Escherichia coli. In addition, the analgesic effect of CA-AgNPs was investigated for the first time in the literature by tail-flick and hot plate methods, and statistically significant results were obtained for both methods. Taken together, these results suggest that CA-AgNPs can be used as an effective antibacterial and analgesic agent in a variety of biomedical applications, including coating wound dressings.Öğe Investigation on selective adsorption of Hg(II) ions using 4-vinyl pyridine grafted poly(ethylene terephthalate) fiber(Wiley, 2012) Bozkaya, Ogun; Yigitoglu, Mustafa; Arslan, MetinIn the work, poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) monomer using benzoyl peroxide (Bz(2)O(2)) as initiator in aqueous media. The removal of Hg(II) ions from aqueous solution by the reactive fiber was examined by batch equilibration technique. Effects of various parameters such as pH, graft yield, adsorption time, initial ion concentration, and adsorption temperature on the adsorption amount of metal ions onto reactive fibers were investigated. The optimum pH of Hg(II) was found 3. The maximum adsorption capacity was found as 137.18 mg g(-1). Moreover such parameters as the adsorption kinetics, the adsorption isotherm, desorption time and the selectivity of the reactive fiber were studied. The adsorption kinetics is in better agreement with pseudo-first order kinetics, and the adsorption data are good fit with Freundlich isotherms. The grafted fiber is more selective for Hg(II) ions in the mixed solution of Hg(II)-Ni(II), Hg(II)-Zn(II), and Hg(II)-Ni(II)-Zn(II) at pH 3. Adsorbed Hg(II) ions were easily desorbed by treating with 1M HNO3 at room temperature. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012Öğe Novel Electrospun Cotton-Like Nano/Microfiber from Waste Polycarbonate Plastic for Use as Filler Fiber in Outerwear Textiles(Korean Fiber Soc, 2023) Bozkaya, OgunSynthetic fibers, which have many different uses, have replaced natural filling materials as filling fibers in clothing textiles today. In the textile industry, the use of recycling plastics has gained importance due to the difficulties in raw material supply, energy saving and increasing environmental problems. Polycarbonate (PC) is an important engineering plastic with increasing waste due to its use in many industries in recent years. The aim of this study is to produce cotton-like (CL) material from waste PC (wPC) plastic by electrospinning method to be used as filling fiber in outerwear textiles. The synthesized CL-rPC material was characterized using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. In addition to these, properties that determine textile comfort such as wettability, water vapor transmission rate (WVTR), water adsorption capacity (WAC) and thermal insulation were investigated. Morphological analysis showed that the mostly nano-sized fibers were smooth and bead-free. The mean fiber diameter was determined as 585 +/- 373 nm. The FTIR spectra of the wPC and CL-rPC nano/microfibers (CL-rPC NMFs) were compared and the similarity between them was found to be 98.39%. Water contact angle, WVTR and WAC of CL-rPC NMFs material were measured as 139.15 +/- 0.07 degrees, 6103.41 +/- 117.76 g/m(2)/day and 17.53 +/- 1.81%, respectively. Moreover, the thermal conductivity of CL-rPC NMFs material was determined as 0.0363 +/- 0.0094 W/mK. The results reveal that CL-rPC NMFs material produced from recycled PC can be a potential candidate for filling fiber applications that can provide thermal comfort conditions in outerwear textiles.Öğe Physico-chemical characterization of food grade natural spring salt from the Central Anatolia region of Turkey and investigation of its microplastic content(Springer India, 2024) Bozkaya, Ogun; Aluc, YasarDelice salt is a natural spring salt obtained from the evaporation of spring water from the Central Anatolia region of Turkey and is a food grade salt with a geographical indication certificate. The aim of this study was to evaluate the compliance of Delice natural spring salt (Delice NSS), a commercial product, with food grade criteria by physicochemical characterizations and to investigate whether it contains microplastics. The NaCl%, moisture suspended solids and acid insoluble matter contents of Delice NSS were analyzed and determined as 98.79% (w/w), 0.301% (w/w), 0.16% (w/w) and 0.01% (w/w), respectively. Sodium, other minerals, and heavy metals were analyzed by inductively coupled plasma-optical emission (ICP-OES) spectrometry. In addition, fluoride, nitrate, and sulphate ions were analyzed by ion chromatography (IC). The chemical and thermal properties of Delice NSS were characterized by FTIR, X-ray fluorescence (XRF) and thermogravimetric analyzer (TGA). Moreover, Delice NSS was investigated whether it contains microplastics and some particles were detected under fluorescence microscopy. However, it was concluded that particles were not microplastics after TGA and FTIR analyses. The results revealed that Delice NSS does not carry a risk in terms of physicochemical properties as a foodstuff.Öğe Production and characterization of hybrid nanofiber wound dressing containing Centella asiatica coated silver nanoparticles by mutual electrospinning method(Pergamon-Elsevier Science Ltd, 2022) Bozkaya, Ogun; Arat, Esra; Gok, Zehra Gun; Yigitoglu, Mustafa; Vargel, IbrahimThe aim of this work is to produce a therapeutic and antimicrobial nanofiber wound dressing material with suitable air permeability, water vapor transmission, water absorption, porosity, thermal and mechanical strength. For this purpose, first of all, Centella asiatica (CA) coated silver nanoparticles (CA-AgNPs) are synthesized with using CA extract as reducing and stabilizing agent. The green synthesized CA-AgNPs are characterized by UV-Vis spectroscopy, transmission electron microscope (TEM), zeta potential and fourier transform infrared (FTIR) spectroscopy measurements. The obtained CA-AgNPs give a single peak in the 420-430 nm range between 200 and 700 nm due to surface plasmon resonance (SPR). The average zeta potential and size of CA-AgNPs is found to be-30.4 mV and 14.8 +/- 7.3 nm, respectively. Then, poly caprolactone (PCL) and polyethylene oxide (PEO) nanofibers composition containing CA-AgNPs is synthesized by mutual electrospinning method. Before electrospinning, the PCL solution (12% w/v in chloroform/methanol (70%/30%, v/v)), PEO solution (3.5%, w/v in water) and PEO solutions containing 1%, 5% and 10% (v:v) of CA-AgNPs are prepared. In electrospinning experiments, to synthesis the PCL/PEO nanofibers containing CA-AgNPs, an electrospinning set-up consisting of two high voltage sources, an aluminum rotary roller collector and two syringe pumps (one with a double syringe and the other with a single syringe) is used. To produce the wound dressing materials, PEO solutions containing CA-AgNPs are placed on the double syringe pump and PCL solution is placed on the single syringe pump. The surface and physico-chemical properties of the produced hybrid nanofibers are characterized by field emission scanning electron microscopy (FESEM), energy dispersion spectrometry (EDS), FTIR, X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET) surface area and porosity analyzer. Also, the thermal and mechanical properties of the obtained materials are investigated. In addition, the air permeability, water uptake capacity, water contact angle, water vapor transmission, in vitro degradation and silver release behavior of the samples are investigated. The results show that mutual dual-spinneret electrospinning technique combines the features of dissimilar components without corruption. Moreover, the in vitro degradation profile and silver release results show that these nanofibers could be used in wound dressing applications in the long term. With antimicrobial studies, PEO/ PCL nanofibers containing 5% and 10% CA-AgNPs are found to be effective against Staphylococcus aureus, Escherichia coli and Candida albicans. Also, the cytotoxic properties of nanofibers are investigated by MTT (3-[4,5dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and results show the good biocompatibility for L929 fibroblast cells. Results reveal that CA-AgNPs loaded PCL/PEO hybrid nanofibers materials synthesized in this study has a promising potential for wound healing applications.Öğe Production of 2-hydroxyethyl methacrylate-g-poly(ethylene terephthalate) nanofibers by electrospinning and evaluation of the properties of the obtained nanofibers(WILEY, 2020) Gok, Zehra Gun; Inal, Murat; Bozkaya, Ogun; Yigitoglu, Mustafa; Vargel, IbrahimNanofiber production was investigated from poly(ethylene terephthalate) (PET) polymers functionalized with hydroxyethyl methacrylate (HEMA) by grafting of HEMA monomers onto the PET fibers. HEMA grafted PET (PET-g-HEMA) copolymers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy. PET and PET-g-HEMA were dissolved in trifluoroacetic acid and nanofibers were obtained by electrospinning. It was found that the PET and PET-g-HEMA polymers having grafting yield 20 and 55% could be converted to continuous, smooth, and beadles nanofibers. For characterization of the nanofiber membranes, thermogravimetric analysis, differential scanning calorimeter analysis, surface contact angle measurement, porosity analysis, and mechanical tests were applied. When compared with the original PET nanofibers, the thermal properties and degradation process of PET-g-HEMA nanofibers changed according to the amount of HEMA present in the structure of nanofibers. The contact angles of the nanofibers obtained from PET-g-HEMA polymers decreased whereas the water retention ability of the nanofibers increased compared to original PET nanofibers. The porosity of PET-g-HEMA nanofibers was found be high compared to PET nanofibers and whereas the mechanical properties of PET was higher than PET-g-HEMA nanofibers. The obtained nanofibers can be used in many fields such as biomaterial applications.Öğe Removal of anionic dyes with glycidyl methacrylate-grafted polyethylene terephthalate (PET) fibers modified with ethylenediamine(Springer, 2021) Bozkaya, Ogun; Gunay, Kubra; Arslan, Metin; Gun Gok, ZehraIn this work, the epoxy groups of poly (ethylene terephthalate) PET copolymers grafted with glycidyl methacrylate (GMA) were modified with ethylenediamine (EDA) to form exclusive adsorbent for removal of congo red (CR) and acid violet7 (AV-7) in the aqueous environment. The graft copolymers (GMA-g-PET) were synthesized with different grafting yield by a radical polymerization process with using benzoyl peroxide (Bz(2)O(2)) as radical initiator. Amination of GMA-g-PET fibers using EDA was studied in different solvents, and maximum yield (w/w %) was obtained in the toluene. The grafted and modified fibers were analyzed by CHNS organic elemental analyzer, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (C-13-NMR). By SEM analysis, the morphological changes have been shown after grafting. The chemical changes after grafting and addition of EDA to the fibers have been proven with FTIR, NMR and elemental analysis. The thermal properties of the grafted and aminated fibers were researched with thermogravimetric analysis and differential scanning calorimeter analysis. The removal of dyes by the EDA-GMA-g-PET fibers was investigated in aqueous medium at different conditions. Optimum conditions of different parameters such as pH of medium, graft yield of GMA on the fibers, adsorption duration, initial concentration of dye molecules and effect of graft yield on amination reaction were examined. The optimum pH of CR and AV-7 removal was found 5 and 3, respectively. The removal yield was found about 100% for both dyes while initial concentration of dyes was changed from 10 to 400 mg/L. Adsorbed dyes with the fibers were desorbed with 1 M NaOH at room conditions.Öğe Vitex Agnus-Castus L. Nanoparticles: Preparation, Characterization and Assessment of Antimicrobial and Anticancer Activity(Wiley-V C H Verlag Gmbh, 2023) Ekici, Seda; Bozkaya, Esra; Bozkaya, Ogun; Cerci, Nebahat Aytuna; Aluc, Yasar; Ekici, HusamettinThis study was aimed to synthesise antimicrobial and therapeutic silver nanoparticles (AgNPs) by green synthesis method using Vitex agnus-castus L. (VAC) seed extract. The synthesised VAC seed extract coated AgNPs were characterised by UV-Vis spectrometry, Zeta analysis and FT-IR spectrometry. The antifungal, antimicrobial, cytotoxicity by MTT assay, and anticarcinogenic activities on HeLa cells line were investigated. VACAgNPs exhibited high antimicrobial activity against S. aureus with a zone diameter of 11.3 +/- 0.6 mm. In addition, the cytotoxicity of VAC-AgNPs was evaluated using the L929 fibroblast cell line and the HeLa cells line, with AgNPs applied at six different concentrations. At a concentration of 5.0 mM, viability was found to be 47.6%+/- 4.2% in L929 fibroblast cells and 39.6%+/- 7.9% in HeLa cells, suggesting a potential antiproliferative effect of VAC-AgNPs on HeLa cancer cells. The IC50 values of VAC-AgNPs against the HeLa cell line were calculated as 2.94 mu g/ml.
