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Öğe Adsorptive removal kinetics of anionic dye onto chitosan films doped with graphene oxide: An in situ fluorescence monitoring(Taylor & Francis Inc, 2018) Kahya, Nilay; Bener, Semira; Kaygusuz, Hakan; Evingur, Gulsen Akin; Erim, F. BediaThe aqueous adsorption of a fluorescent dye (pyranine) onto crosslinked chitosan-graphene oxide composite films was studied. In situ fluorescence monitoring technique is introduced as easy and fast experimental technique to select optimal adsorbent conditions. The effect of ionic crosslinker on adsorption was studied with sodium tripolyphosphate, trisodium citrate, and sodium sulfate, respectively. Among the crosslinkers, it was realized that sodium sulfate crosslinked films showed a greater adsorption rate for pyranine than the other two types of crosslinked films. Recently, graphene oxide is of interest as a filler compound for many biopolymer applications due to its favorable thermal, mechanical and surficial properties. In the present study, graphene oxide incorporation increased adsorption rate of the dye and the mechanical strength of ionically crosslinked chitosan films. The adsorption behavior of the adsorbent was explained by a kinetic model. Samples were characterized using scanning electron microscopy, thermogravimetric analysis, swelling experiments and tensile testing method.Öğe Antibacterial nano cerium oxide/chitosan/cellulose acetate composite films as potential wound dressing(Pergamon-Elsevier Science Ltd, 2020) Kalaycıoğlu, Zeynep; Kahya, Nilay; Adımcılar, Veselina; Kaygusuz, Hakan; Torlak, Emrah; Akın-Evingür, Gülşen; Erim, F. BediaNovel chitosan and cellulose acetate polymer composites with nanosized cerium oxide were prepared as potential wound dressing materials. Chitosan and cellulose acetate are natural polymer derivatives with biocompatible properties. Both polymers can be dissolved in formic acid. The polymer composite was formed by solvent-casting method. The formed films were not soluble in water. In order to improve antibacterial, thermal, and mechanical properties of the composite material, films were loaded with nanosized cerium oxide. Films were characterized with thermogravimetric, scanning electron microscopy with energy-dispersive X-ray spectroscopy, mechanical, ultraviolet-visible light transmittance, water solubility, pH, moisture content, water vapor transmission rate, swelling, and antibacterial tests. The physical properties and antibacterial characteristics of the films are promising for further research as a potential wound covering material.Öğe Biopolymer-assisted green synthesis of functional cerium oxide nanoparticles(Springer International Publishing Ag, 2020) Kaygusuz, Hakan; Erim, F. BediaCerium oxide nanoparticles were synthesized by thermal decomposition of cerium alginate biopolymer gel at 450 degrees C, where alginate both acts as a precursor and a template. The synthesis is a green, facile and one-step method and the resulting nanoparticles have functionalized surface. The resulted material were characterized using X-ray diffraction for confirmation of cerium oxide, crystallite size analysis and grain size distribution. Transmission electron microscopy was used for the particle size determination, hydrodynamic size estimation was studied by dynamic light scattering and surface characteristics were analyzed using zeta potential measurements. Results show the presence of spherical particles with a size of < 5 nm. Having only a negative surface charge in such a wide pH range will ensure that the behavior of obtained nanoparticles in different environments is predictable. Isoelectric point of the synthesized material is significantly different from non-functionalized cerium oxide, and indicates the surface functionality, which is an important property for biocompatibility.Öğe Effective photocatalytic degradation of malachite green dye by Fe(III)-Cross-linked alginate-carboxymethyl cellulose composites(2022) Karadeniz, Duygu; Kahya, Nilay; Erim, F. BediaFe(III) ion cross-linked alginate-carboxymethyl cellulose composite beads (Fe@(Alg-CMC)) were prepared and used as a novel photocatalyst for the degradation of malachite green (MG) dye. Fe (III) ions bound to the carboxyl groups of the biopolymer composite provided reactive radicals under UV light, and degradation of the dye in an aqueous solution occurred at a high percentage and in a short time. Unlike Fenton’s reaction, effective degra- dation of the dye was carried out without adding H2O2 to the medium. Optimum conditions of dye degradation were investigated. Under UV-A light, 98.8%±0.7% dye degradation was achieved at pH 4 of 10 ppm MG solution with 0.1 g of Fe@(Alg-CMC) beads in 30 min. Experimental results fitted Langmuir-Hinshelwood kinetic modeling, which explains the kinetics of the heterogeneous catalytic processes. A rate constant (k) of 0.115 ± 0.001 minÖğe Electric-field induced phase transitions in capillary electrophoretic systems(Aip Publishing, 2021) Kaygusuz, Hakan; Erim, F. Bedia; Berker, A. NihatThe movement of particles in a capillary electrophoretic system under electroosmotic flow was modeled using Monte Carlo simulation with the Metropolis algorithm. Two different cases with repulsive and attractive interactions between molecules were taken into consideration. Simulation was done using a spin-like system, where the interactions between the nearest and second closest neighbors were considered in two separate steps of the modeling study. A total of 20 different cases with different rates of interactions for both repulsive and attractive interactions were modeled. The movement of the particles through the capillary is defined as current. At a low interaction level between molecules, a regular electroosmotic flow is obtained; on the other hand, with increasing interactions between molecules, the current shows a phase transition behavior. The results also show that a modular electroosmotic flow can be obtained for separations by tuning the ratio between molecular interactions and electric field strength.Öğe Evaluation of some Turkish Salvia species by principal component analysis based on their vitamin B2, mineral composition, and antioxidant properties(Elsevier Science Bv, 2019) Gezek, Görkem; Hashemi, Parya; Kalaycıoğlu, Zeynep; Kaygusuz, Hakan; Sarıoğlu, Gözde; Döker, Serhat; Erim, F. BediaIn this study, 14 Turkish Salvia species, 12 of which are endemic, were characterized based on their vitamin B2, mineral, total phenolic contents, and antioxidant activities. Determination of vitamin B2 in Salvia species was achieved by a fast and sensitive capillary electrophoresis technique using a laser induced fluorescence (LIF) detector. All samples contain vitamin B2 ranging from 0.165 to 1.19 mg/100 g. Fifteen elements (Ca, K, Na, Mg, Fe, Mn, Zn, Li, Cu, Co, Al, V, Sr, Sn, and Ni) were determined in each Salvia sample by inductively coupled plasma-mass spectrometry (ICP-MS). Total phenolic contents of the Salvia samples, ranging from 11.8 to 119 mg gallic acid equivalents (GAE)/g, were determined using the Folin-Ciocalteu's method. The antioxidant activities were evaluated by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power assay (FRAP). Analysis data were evaluated by principal component analysis (PCA) and differentiation among Salvia species was shown.Öğe Foam-based antibacterial hydrogel composed of carboxymethyl cellulose/polyvinyl alcohol/cerium oxide nanoparticles for potential wound dressing(2024) Orhan, Burcu; Karadeniz, Duygu; Kalaycıoğlu, Zeynep; Kaygusuz, Hakan; Torlak, Emrah; Erim, F. BediaFoam-based wound dressing materials produced by dispersing gas phases in a polymeric material are soft, adapt to the body shape, and allow the absorption of wound exudate due to their porous structure. Most of these formulations are based on synthetic substances such as polyurethane. However, biopolymers have entered the field as a new player thanks to their biocompatible and sustainable nature. Incorporating biopolymers in formulations is gaining interest in scientific literature, and we extend this approach by adding antibacterial cerium oxide nanoparticles to biopolymer formulation. We introduce a novel biopolymer composite of carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and cerium oxide nanoparticles (CeO2 NPs), namely PVA-CMC@CeO2. This mixture was first foamed and then cross-linked with sodium tetraborate solution, followed by a freeze-thaw process. After the novel material's spectroscopic, structural, and morphological characterization, we investigated its swelling, drug-delivery, antibacterial, and biodegradability properties PVA-CMC@CeO2 dressing effectively inhibits Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) growth and delivers the antibiotic drug silver sulfadiazine for up to 6 h. The antibacterial properties, good swelling, and drug release profile of the blend material show promising potential in wound care applications.Öğe Naturally occuring nitrate and nitrite in nutrients : determinations in Anatolian honey-bee pollens by capillary electrophoresis(Altınbaş Üniversitesi, 2021) Kalaycıoğlu, Zeynep; Karadeniz, H. Sena; Erim, F. BediaThe aim of this work is the simultaneous determination of nitrate and nitrite in a set of bee-pollens of Anatolia using a capillary electrophoretic technique. Separation and determination conditions were 30 mM formic acid/formate buffer at pH 4.0. In earlier steps with pollen samples, only nitrate anion was detected. Consequently, a sample stacking method was applied to increase the detection sensitivity of both anions for the pollen samples. In a stacking operation, the conductivity of separation buffer should be higher than the sample zone. The conductivity of the separation buffer was increased by the addition of 30 mM sodium sulfate. Injection condition was 160 s at 50 mbar. The calibration curves show linear dynamic ranges from 1.5 to 30 μmol/L and 1.5 to 10 μmol/L with correlation coefficients of 0.989 and 0.999 for nitrate and nitrite ions, respectively. All the pollen samples contained appreciable amounts of nitrate (from 2.880 ± 0.055 to 18.72 ± 0.46 mg/kg). Low levels of nitrite were found in all samples (from 0.048 ± 0.008 to 0.301 ± 0.001 mg/kg).Öğe Sustainable alginate-carboxymethyl cellulose superabsorbents prepared by a novel quasi-cryogelation method(Springer, 2022) Orhan, Burcu; Kaygusuz, Hakan; Erim, F. BediaThe research in biopolymer-based superabsorbents is gaining importance in the green chemistry feld thanks to their environmentally friendly properties. In this study, a biopolymer-based superabsorbent made of calcium ion crosslinked alginate/ carboxymethyl cellulose composite was prepared by a new quasi-cryogelation process, where the complete ionic gelation takes place before the freezing step, in contrast to the conventional cryogelation technique in which gelation occurs under semi-frozen conditions. Thanks to the facile quasi-cryogelation method, the morphology of the gels changed and a signifcant increase in water absorption properties has been achieved. The swelling properties of the material were investigated in distilled water and diferent physiological fuids. Results show that the proposed material shows good water absorption property where a water absorption of 2343% was reached and even after fve cycles this value was 1200%. As a result, this study reports a biopolymer-based sustainable superabsorbent which is appropriate for various applications such as the removal of pollutants from water or diaper production.
