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Öğe Mechanically stable superhydrophilic antifog surface by microwave assisted sol-gel method(Elsevier B.V., 2021) Okkay, Hikmet; Satı, Sadık; Cengiz, UğurIn this study, optically transparent and mechanically stable of superhydrophilic composite thin films were fabricated via a low-cost one-step one pot microwave-assisted sol-gel technique. The microwave reaction time was optimized according to surface characterization of homo TMOS surfaces. The reaction time was arranged as 17.5 min having low cost compared to the conventional sol-gel technic. The wettability performance and antifogging behavior of PVA-TMOS composite films were investigated according to variation of the PVA content. The static contact angle values of the composite surfaces were found to vary between 30o and 5o. Superhydrophilic surface having tilt angle is 9o showed a good antifogging performance. Mechanical durability of the composite surface was also characterized by scratching and adhesive tape test. In addition, the time depending water contact angle was also measured for 100 days. It is found that TMPV96 composite film having 0.096 (wt,%) content of PVA showed higher mechanical performance with transparent superhydrophilic surface.Öğe Synthesis and multicolor, photophysical, thermal, and conductivity properties of poly(imine)s(Elsevier B.V., 2021) Kaya, İsmet; Solak, Elif; Kamacı, MusaBackground: Thiazole-based conjugated have been attracted much attention due to their desirable photophysical properties. Based on this, we aimed to prepare thiazole-based poly(imine)s with tunable multicolor emission behavior in the present paper. Methods: Thiazole-based Schiff bases and poly(imine)s were prepared via condensation, and oxidation reactions, respectively. The tunable multicolor behavior of the poly(imine)s was also clarified using fluorescent measurements. Findings: The conductivity, thermal, photophysical, multicolor, morphological and electrochemical properties of the thiazole-based compounds were also clarified. Multicolor behavior of the poly(imine)s was demonstrated that they were emitted blue, green, and yellow emission colors when excited at 350, 420, and 480 nm, respectively. Thermal properties showed that the (poly(imine)s were exhibited good thermal stability. It was found that the thiazole-based poly(imine)s were exhibited a semiconductor behavior after iodine doped. The results indicated that the prepared poly(imine)s were exhibited tunable multicolor property with good thermal stability, and electrical conductivity.Öğe Modification of halloysite clay nanotubes with various alkyl halides, and their characterization, blood compatibility, biocompatibility, and genotoxicity(Elsevier Ltd, 2021) Can, Mehmet; Demirci, Şahin; Yıldırım, Yıldız; Çakır Çoban, Canan; Türk, Mustafa; Şahiner, NurettinHalloysite nanotubes (HNTs) clay were modified with alkyl halides, bromoethane (BrE), bromodecane (BrD), and bromooctadecane (BrOD), respectively. The FT-IR spectra of modified HNTs demonstrated an increase in the intensity of aliphatic –CH2 peaks at 2920 and 2850 cm−1 proportional to the number of C atoms in the modifying agent confirming the success of chemical modification with corresponding alkyl halides. Surface charge of NaOH treated HNTs, −65.7 ± 5.1 mV was increased to −37.1 ± 2.4, −40.6 ± 5.3, and −44.7 ± 1.9 mV, respectively upon chemical modification with BrE, BrD, and BrOD. The Surface area of the HNT clays, 43.2 ± 1.3 m2/g was also increased to 59.8 ± 2.7, 56.9 ± 2.1, and 47.9 ± 1.7 m2/g for BrE, BrD, and BrOD modified HNT clays, respectively. Base-activated HNT clays at 1 mg/mL concentration found to be nonhemolytic with 3.5 ± 1.2% hemolysis ratio, whereas HNT-BrOD clays were slightly exceeded hemolytic safety level with 6.6 ± 0.2% hemolysis induction. Base-activated HNT and HNT-BrOD clays were found to show antithrombogenic character with more than 100% blood clotting indexes,107.6 ± 1.8, and 106.5 ± 1.9%, respectively. Cytotoxicity studies of HNTs on L929 fibroblast cells revealed that HNTs in 12.5–200 μg/mL concentration range were shown dose-dependent cell viability, and above 50% cell viability was maintained at 200 μg/mL in all forms of HNT based clays administered.Öğe Amperometric nonenzymatic glucose biosensor based on graphite rod electrode modified by Ni-nanoparticle/polypyrrole composite(Elsevier Inc., 2021) Emir, Gamze; Dilgin, Yusuf; Ramanaviciene, Almira; Ramanavicius, ArunasThis study reports non-ezymatic electrocatalytic amperometric glucose biosensor based on a graphite rod electrode (GRE) modified with biomimetic-composite consisting of Ni nanoparticles (Ni-NPs) and polypyrrole (Ppy) prepared by 1 cycle electro polymerization of pyrrole monomer (Ni-NPs/Ppy(1)/GRE). During the modification of GRE, the electropolymerization of pyrrole and the electrodeposition of Ni-NPs onto GRE surface were consequentially performed by potential cycling. Surface morphology of Ni-NPs/Ppy(1)/GRE electrode was evaluated by atomic force microscopy and scanning electron microscopy based imaging, and electrochemical characterization of electrodes was performed by electrochemical impedance spectroscopy and cyclic voltammetry. Cyclic voltammograms recorded in the presence of glucose show that Ni-NPs/Ppy(1)/GRE at + 500 mV vs Ag/AgCl exhibits efficient electrocatalytic oxidation activity towards glucose, while the oxidation of glucose was not observed at a bare GRE. Amperometric sensing of glucose was performed by Ni-NPs/Ppy(1)/GRE at constant + 450 mV vs Ag/AgCl electrode potential in 0.10 mol L−1 NaOH. Ni-NPs/Ppy(1)/GRE-based sensor, which was characterized by a wide linear glucose determination range between 1.0 and 1000 µmol L−1 with a limit of detection of 0.4 µmol L−1 and a sensitivity of 2873 µA mmol−1 L cm−2. The applicability of here reported Ni-NPs/Ppy(1)/GRE-based sensor has been demonstrated by the determination of glucose concentrations in real samples.Öğe Synthesis, spectral properties, crystal structure and theoretical calculations of a new geminal diamine: 2,2,2-Trichloro-N,N′-bis(2-nitrophenyl)-ethane-1,1-diamine(Elsevier B.V., 2021) Aydın, Fatma; Arslan, N. BurcuA new 2,2,2-trichloro-N,N׳-bis(2-nitrophenyl)-ethane-1,1-diamine was synthesized by the reaction of 2-nitroaniline in DCM with the chloral formed by distillation of chloral hydrate over concentrated H2SO4. The structure of the title compound was identified by means of FT-IR, 1H NMR, and 13C NMR spectroscopic techniques. The crystal structure of the title compound has also been examined by using X-ray crystallographic techniques and found to be crystallized in the monoclinic crystal system and space group P21/n with the unit cell parameters: a = 7.7075(12) Å, b = 7.7396(10) Å, c = 28.247(4) Å, β = 93.602(5)°, V = 1681.7(4) Å3, Dx = 1.602 Mg m − 3, and Z = 4 respectively. The calculated electronic structure properties of the title molecule such as HOMO-LUMO analysis, molecular electrostatic potential (MEP) map, and the Mulliken charge distributions were investigated by using the density functional theory (DFT) method. Theoretically calculated values exhibit the chemically hard, high kinetic stable and less reactive molecule.Öğe Synthesis and characterization of magnetic ZnCl2-activated carbon produced from coconut shell for the adsorption of methylene blue(Elsevier B.V., 2021) Karaer Yağmur, Hatice; Kaya, İsmetIn this research, a magnetic-activated carbon composite was synthesized to investigate its adsorption to methylene blue dye. Active carbon (ACz) was produced by ZnCl2 activation of coconut shell (char: ZnCl2, 2:1). Magnetic activated carbon (MACz) was prepared via an easy method by chemical co-precipitation of Fe3+/Fe2+. The pore diameter, pore-volume, and surface area of MACz were determined from N2 adsorption isotherms. The ACz and MACz were characterized by several techniques such as BET, SEM/EDX, FT-IR, XRF, VSM, TGA, and pHpzc analysis. The average particle size, particle size distribution, and zeta potential of MACz were determined by Zetasizer. The zero point charge of the MACz was determined as approximately 4.9 pH. Moreover, the adsorption by MACz was investigated as kinetically and thermodynamically for removal of methylene blue (MB) from aqueous solution. The kinetics and thermodynamic parameters were also calculated. According to the results, the adsorption process was determined as endothermic. The Langmuir and Freundlich isotherms models were used and it was found that adsorption of MB onto MACz best fitted to Freundlich model according to RMSE, SSE, and R2 values. The maximum adsorption capacity of the composite was calculated as 156.25 mg/g. Thermodynamic parameters (ΔHo, ΔGo, and ΔSo) were also calculated, which revealed that the adsorption process is spontaneous.Öğe Dye sensitized solar cell-based optoelectronic device using novel [Ru(L1)(L2)(NCS)2] complex(Elsevier B.V., 2021) Dayan, Osman; Gençer İmer, Arife; Tercan, Melek; Dere, Ayşegül; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; Yakuphanoğlu, FahrettinA dye sensitized solar cell-based photodiode was prepared using novel [Ru(L1)(L2)(NCS)2] complex for solar energy and optoelectronic applications. The new heteroleptic ruthenium(II) complex [Ru(L1)(L2)(NCS)2], was synthesized from the reaction of (pyridyl)benzimidazole ligands. The possible usage of [Ru(L1)(L2)(NCS)2] complex in dye synthesized solar cell-based photodiode was investigated using electrical and capacitance characteristics. The device was irradiated under various solar light intensities. The change in photocurrent of the device confirms the photoconducting behavior of prepared device. The device exhibited both the photocapacitance and photoresponse behavior with solar illumination. The obtained optoelectrical results suggest that the studied photodiode with [Ru(L1)(L2)(NCS)2] complex could be used in optoelectronic device for optical switching and controlling applications.Öğe Synthesis and characterization of biodegradable and antioxidant phosphazene-tannic acid nanospheres and their utilization as drug carrier material(Elsevier Ltd, 2021) Önder, Alper; Özay, HavaIn this study, hexachlorocyclotriphosphazene (HCCP) and tannic acid (TA) were used at different stoichiometric ratios to synthesize cyclomatrix-type polymeric materials with different surface features and dimensions. Using different reactive ratios, the structure and surface functional groups of the synthesized polymeric particles were explained using Fourier-Transform Infrared Spectroscopic (FTIR), Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric (TG) analysis techniques. With morphologically fully spherical structure and mean 234.82 ± 49.37 nm dimensions, Phz-TA (4:1) nanospheres were researched for in vitro biodegradability, antioxidant features, and usability as a drug release system. In vitro biodegradability of Phz-TA (4:1) nanospheres was investigated at pH = 7.0 and pH = 1.2. Determined to degrade in 8–10 h at these pH values, nanospheres were used for releasing of Rhodamine 6G as a model drug. Due to the rich phenolic structure of the contained tannic acid units, nanospheres were determined to simultaneously have antioxidant features. Thus, this study determined that Phz-TA nanospheres with in vitro biodegradability and antioxidant features are promising polymeric materials for use as a potential drug-carrier in the future.Öğe Boron Rejection from Aqueous Solution and Wastewater by Direct Contact Membrane Distillation(2020) Tan, Burcu; Selengil, Uğur; Bektaş, Tijen EnnilBoron is widely used in various areas of modern technology. Due to the environmental problems arising during the production and use, the studies on the removal and recovery of boron from wastewater have been increased recently. Membrane distillation (MD) system is smaller in size with respect to other common distillation systems and needs lower operating temperatures. In addition, the equipment costs are reduced and the safety of the process increases since it operates at lower pressures. Moreover, the membrane distillation process can remove pollutants from water without using chemicals. In this study, boron rejection from aqueous solutions and wastewater was investigated by using direct contact membrane distillation (DCMD) system where both surfaces of a porous hydrophobic membrane were in contact with liquid streams. The effects of various parameters (pH, feed concentration, feed temperature, etc.) on boron rejection were investigated and the highest boron rejection was found to be 50 % when pH=10 at 50 degrees C and with feeding by a pump of 54 rpm. According to the test results of wastewater from Kirka Borax treatment plants, the mean distillate fluxes were found as 13, 16 and 14 L/m(2)h at the feed temperatures of 30, 40 and 50 degrees C, respectively. The boron removal percentages were found to be 47, 64 and 48 % at 30, 40 and 50 degrees C, respectively. It was observed in the XRD spectra that the crystals in wastewater mainly consist of Na2B(OH)(4)Cl and Mg2B2O5 structures.Öğe Boron rejection from aqueous solution and wastewater by direct contact membrane distillation(Yildiz Technical University, 2021) Tan, Burcu; Selengil, Uğur; Bektaş, Tijen EnnilBoron is widely used in various areas of modern technology. Due to the environmental problems arising during the production and use, the studies on the removal and recovery of boron from wastewater have been increased recently. Membrane distillation (MD) system is smaller in size with respect to other common distillation systems and needs lower operating temperatures. In addition, the equipment costs are reduced and the safety of the process increases since it operates at lower pressures. Moreover, the membrane distillation process can remove pollutants from water without using chemicals. In this study, boron rejection from aqueous solutions and wastewater was investigated by using direct contact membrane distillation (DCMD) system where both surfaces of a porous hydrophobic membrane were in contact with liquid streams. The effects of various parameters (pH, feed concentration, feed temperature, etc.) on boron rejection were investigated and the highest boron rejection was found to be 50 % when pH=10 at 50 °C and with feeding by a pump of 54 rpm. According to the test results of wastewater from Kırka Borax treatment plants, the mean distillate fluxes were found as 13, 16 and 14 L m-2 h-1 at the feed temperatures of 30, 40 and 50 °C, respectively. The boron removal percentages were found to be 47, 64 and 48 % at 30, 40 and 50 °C, respectively. It was observed in the XRD spectra that the crystals in wastewater mainly consist of Na2B(OH)4Cl and Mg2B2O5 structures.Öğe The use of titanium dioxide particles embedded in anionic hydrogel composite for photocatalytic degradation of methylene blue(John Wiley and Sons Inc, 2021) Arı, Betül; Sengel, Sultan B.; Şahiner, NurettinPoly(2-acrylamido-2-methyl-1-propane sulfonic acid) (p(AMPS)) anionic hydrogels with 1, 5 and 10 wt% TiO2 particles were prepared by a simultaneous free radical polymerization and crosslinking reaction. The hydrogel composites were tested as photo-catalysts for the degradation of methylene blue (MB) in water. Since MB dye is positively charged, MB should be readily absorbed by the anionic p(AMPS) hydrogel and then degraded by the entrapped TiO2 nanoparticle photocatalysts within the p(AMPS) matrix. Photocatalytic degradation of MB was promoted using a UV lamp (300 W) to activate TiO2 particles and was monitored by UV–Vis spectrometer. Interestingly, the activation energy of 20.58 kJ.mol−1 was found to be one of the lowest reported in the literature. The reusability and regeneration efficiency studies of the composite catalyst showed that the p(AMPS)-TiO2 composite catalyst possessed 90% activity even after five repetitive use and maintained above 85% activity even after the second regeneration. Using different organic scavengers such as ascorbic acid, dimethylsulfoxide and methanol, it was determined that the main reactive species in the photodegradation of MB dye are electrons and superoxide ions. p(AMPS)-TiO2 composite hydrogel has potential to be used as a good photocatalyst in degradation of toxic dyes and some organic pollutants.Öğe Nanogel synthesis by irradiation of aqueous polymer solutions(Springer, 2021) Sütekin, S. Duygu; Güven, Olgun; Şahiner, NurettinNanogels/microgels are intramolecularly crosslinked particles with submicron diameters that can swell in a suitable solvent due to their three-dimensional network structure. Nanogels provide beneficial features such as flexibility, biocompatibility, high stability and swelling, fixed shape, large surface/volume ratio, fast stimuli-responsive behavior, etc. Therefore, there is growing interest to further elaborate nanogel formulations in preclinical applications as therapeutics, diagnostics, or nanosensors. However, conventional nanogel synthesis methods may end up with nanogels containing toxic residuals, e.g., initiator, crosslinking agent, and fragments which possess a major disadvantage in biomedical applications requiring tedious purification steps. This chapter reviews the synthesis of nanogels by irradiation of dilute aqueous polymer solutions to induce intramolecular crosslinking by gamma rays or accelerated electrons. This simple, ecofriendly, and cost-effective manufacturing method eliminates the purification step and provides the possibility to produce clean nanogels with desired sizes at room temperature. In the formation of nanogels, the degree of crosslinking can be controlled by polymer solution properties as well as operational parameters such as dose rate of radiation source and total absorbed dose. The method can be applied to many water-soluble polymers, copolymers, or interpolymer complexes for the development of nanogels with desired sizes and properties.Öğe Synthesis, characterization, thermal and kinetic properties of chalcone methacrylamide polymers containing halogen group in side chain(Springer Science and Business Media Deutschland GmbH, 2022) Solmaz, Adnan; İlter, Zülfiye; Kaya, İsmetAbstract: In this study, first the chalcone compounds abbreviated as CHAL-F, CHAL-Cl and CHAL-Br containing the halogen group in the side chain were synthesized in medium alkaline at 0 °C. Then, chalcone methacrylamide monomers abbreviated as M-F, M-Cl and M-Br containing halogen group in side chain were synthesized by the reaction of the chalcone compounds with methacryloylchloride at 0–5 °C in the presence of triethylamine (E3N). The chalcone methacrylamide polymers abbreviated as P-F, P-Cl and P-Br were prepared by the free radical polymerization at 70 °C, in DMF solution and by 2,2ʹ-azobisizobutyronitrile (AIBN) initiator. The structures of synthesized compounds were characterized by FTIR, UV–Vis and 1H-13C-NMR. Thermal characterizations of polymers were performed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The glass transition temperature (Tg) of P-F, P-Cl and P-Br was found at 103, 129 and 110 °C, respectively, from DSC measurements. According to the Flynn–Wall–Ozawa (FWO) method, the average decomposition activation energy of the P-Br was found as 76.84 kJ mol−1 from the TGA thermograms at different heating rates such as 10, 15 and 20 °C min−1. The contribution of the polar functional groups carried by the synthesized chalcone methacrylamide polymers to some dielectric behavior was examined through the impedance analyzer as a function of frequency. The conductivity values of P-F, P-Cl and P-Br were found 2.00 × 10–9, 2.04 × 10–9 and 1.91 × 10–9 S cm−1, respectively. The SEM images were used to investigate the morphologies of polymers. The surface morphologies and molecular weight distributions of the polymers were imaged by scanning electron microscopy (SEM) and gel permeation chromatography (GPC), respectively. The optical properties of polymers were investigated by UV–Vis and their antimicrobial activities determined by disk diffusion method. The polymers have exhibited good antimicrobial property against Staphylococcus aureus, Klebsiella pneumonia and have exhibited good antifungal property against Candida albicans.Öğe Poly(vinyl amine) microparticles derived from N-Vinylformamide and their versatile use(Springer Science and Business Media Deutschland GmbH, 2022) Demirci, Şahin; Sutekin, S. Duygu; Kurt, Saliha B.; Güven, Olgun; Şahiner, NurettinCationic polymers with primary amine groups that can easily be functionalized or coupled with substrates by complexation or hydrogen bonding are especially advantageous in preparing particles for biomedical applications. Poly(vinyl amine) (PVAm) is a cationic polyelectrolyte containing the highest number of primary amine groups among any other polymers. Here, we introduce a general method in synthesizing PVAm microparticles via a surfactant-free water-in-oil emulsion technique using cyclohexane as the oil phase and aqueous PVAm solution as the dispersed phase. PVAm particles were prepared to employ two different bifunctional chemical crosslinkers, divinyl sulfone (DVS) and poly(ethylene glycol) diglycidyl ether (PEGGE). The prepared particles were further treated with HCl to protonate the amine groups of PVAm within particles. The effect of crosslinker types and pH on the hydrolytic degradation of PVAm particles were also investigated at three different solution pHs, 5.4, 7.4, and 9, to simulate the skin, blood, and intestinal pH environments, respectively. The blood compatibility of the PVAm particles was evaluated by in vitro hemolysis and blood clotting assays. Furthermore, antifungal and antibacterial efficacy of PVAm-based particles and their protonated forms were tested against C. albicans yeast and E. coli, S. aureus, B. subtilis, and P. aeruginosa bacterial strains.Öğe Preparation of composite hydrogels containing fly ash as low-cost adsorbent material and its use in dye adsorption(Springer Science and Business Media Deutschland GmbH, 2022) Önder, Alper; Ilgın, Pınar; Özay, Hava; Özay, ÖzgürAbstract: Recycling industrial wastes is necessary for the economy and the environment. Additionally, it is important to develop high-efficiency adsorbents to prevent severe water pollution caused by wastewater containing dye agents. Here, poly(2-acrylamido-2-methylpropane sulfonic acid)-fly ash composite hydrogel was synthesized with a variety of fly ash proportions with the radical polymerization method. The synthesized composite hydrogel was used for adsorption of methylene blue and methyl orange dyes from water containing dye agents. A variety of parameters such as initial dye concentration, solution pH, anion effects, temperature, contact time and adsorbent amount were investigated for optimization of the adsorption process. The poly(2-acrylamido-2-methylpropane sulfonic acid)-fly ash composite hydrogel was determined to be an effective adsorbent to remove both the cationic dye methylene blue (1438.68 mg g−1) and the anionic dye methyl orange (646.54 mg g−1). Experimental adsorption data were assessed with a variety of isotherm and kinetic models. It was determined that the adsorption of both dye molecules abided by the pseudo-second-order kinetic model. The thermodynamic parameters were determined as ΔH° = − 15.77 ± 5.22 kJ mol−1, ΔS = − 45.05 ± 16.42 J mol−1 K−1 and ΔG° < 0 for MB, ΔH° = − 20.13 ± 4.83 kJ mol−1, ΔS = − 72.87 ± 15.20 J mol−1 K−1 and ΔG° > 0 for MO. In conclusion, a material was synthesized that can be used as a single adsorbent composite material for both anionic and cationic dyes. In addition to the perfect adsorption capacity of this material, it offers reusability and a broad area of application for a variety of dye agents.Öğe Hyaluronic acid (HA)-Gd(III) and HA-Fe(III) microgels as MRI contrast enhancing agents(Elsevier Ltd, 2022) Şahiner, Nurettin; Umut, Evrim; Sağbaş Suner, Selin; Şahiner, Mehtap; Culha, Mustafa; Ayyala, Ramesh S.Hyaluronic acid (HA) was crosslinked with Gd(III) and Fe(III) ions rendering physically crosslinked HA-metal(III) microgels as magnetic resonance imaging (MRI) enhancing contrast agents. These HA-Gd(III) and HA-Fe(III) microgels are injectable with size range, 50–5000 nm in water. The same isoelectric point, pH 1.2 ± 0.1, was measured for both microgels. HA-Gd(III) and HA-Fe(III) microgels are hemo-compatible biomaterials and can be safely used in intravascular applications up to 1000 μg/mL concentration. Furthermore, no significant toxicity was attained as 95 ± 8 and 81 ± 2% cell viability on L929 fibroblast cells at 100 μg/mL of HA-Gd(III) and HA-Fe(III) microgels were measured. Moreover, HA-Gd(III) microgels were found to afford significant contrast improvement capability in MRI with proton relaxivity, r1 = 2.11 mM−1 s−1, comparable with the values reported for Gd(III) labeled functionalized HA gel systems and commercial Gd based contrast agents.Öğe Investigation of thermal behavior of phenol-wood condensation product(Walter De Gruyter Gmbh, 2005) Alma, M. Hakkı; Kaya, İsmet; Acemioğlu, BilalIn this study, the thermogravimetric behavior and activation energy of birch wood (Betula maximoviczina Regel) wastes-phenol condensation product were studied at several different heating rates. The experimental findings were compared to data obtained for commercial phenolformaldehyde condensation products (novalak). From thermogravimetric curves, the percent weight loss of phenolated wood was found to be higher than that of novalak in percent weight loss. Moreover, the activation energies of phenol-wood condensation products were markedly higher than those of novalak for various heating rates. Also, the activation energies of the phenol-wood condensation product along with that of novalak were in the range of activation the energy values of plastics (50-250 kJ/mol K). Furthermore, the initial degradation temperature of the phenol-wood condensation product is about 15 degrees C lower than that of novalak.Öğe Super Porous Carboxymethyl Cellulose–Tannic Acid (TA@CMC) Cryogels with Antioxidant, Antibacterial, and α-Glucosidase Enzyme Inhibition Abilities(Mdpi, 2024) Şahiner, Mehtap; Demirci, Şahin; Şahiner, NurettinHere, super porous carboxymethyl cellulose (CMC) cryogels were synthesized in 10-100% crosslinker and the presence of TA, at varying amounts of TA, e.g., 10 and 25 wt% of CMC under cryogenic conditions (-20 degrees C) as TA@CMCs. To control the degradation of CMC cryogel networks, the crosslinking ratio of divinyl sulfone (DVS:X) to CMC varied at 10, 25, 50, and 100% moles of the CMC repeating unit. Higher hydrolytic degradation was observed for CMC 10%X cryogels at pH 1.0 with 28.4 +/- 1.2% weight loss. On the other hand, the TA-release studies from TA@CMC-based cryogels showed that higher TA releases were observed for both TA@CMC 10% and 25% cryogels at pH 7.4, with 23.6 +/- 1.1, and 46.5 +/- 2.3 mg/g in 480 min, which are equal to almost 24% and 18% of the TA contents of the corresponding cryogels, respectively. The antioxidant properties of TA@CMC cryogels were examined, and worthy antioxidant properties were observed due to the TA. The alpha-glucosidase enzyme inhibition ability of the prepared cryogels was examined at different concentrations by grinding cryogels, and it was determined that TA@CMC 25% cryogel at 3 mg/mL concentration inhibited 70.4 + 1.3% of the enzyme. All bare CMC-based cryogels were found to be non-hemolytic with a less than 1% hemolysis ratio and also effective on the blood coagulation mechanism with blood-clotting index (BCI) values between 62.1 and 81.7% at 1 mg/mL concentrations. On the other hand, TA@CMC 25% cryogels exhibited a slight hemolytic profile with a 6.1 +/- 0.8% hemolysis ratio and did not affect the blood coagulation mechanism with 97.8 +/- 0.4% BCI value.Öğe Synthesis, characterization, and thermal properties of oligo-2-hydroxyphenylbenzaldimine(Marcel Dekker Inc, 2004) Kaya, İsmet; Şenol, Dilek; Koyuncu, SermetIn this study, the oxidative polycondensation reaction conditions of 2-hydroxyphenylbenzaldimine (HPBA) with air oxygen and NaOCl were studied in an aqeous alkaline medium between 50 and 90degreesC. The product was characterized by H-1-NMR, FT-IR, UV-Vis, size exclusion chromatography (SEC), and element analysis techniques. Solubility testing of oligo-2-hyroxyphenylbenzaldimine was investigated by organic solvents such as DMF, THF, DMSO, methanol, ethanol, CHCl3, CCl4, toluene acetonitrile, ethyl acetate, conc. H2SO4, and aqueous alkaline solution. 2-Hydroxyphenylbenzaldimine (96%) was converted to oligomer by oxidation in an aqueous alkaline medium. According to solubility in water, oligo-2-hydroxyphenylben-zaldimine separated into two fractions: oligo-2-hydroxyphenylbenzaldimine (OHPBA-1, undissolved in water) and oligo-2-hydroxyphenylbenzaldimine (OHPBA-II, dissolved in water). According to the SEC technique, the number average molecular weight (M.), mass average molecular weight (M,), and polydispersity index (PDI) values of OHPBA-1 and OHPBA-II were found to be 2166 g mol(-1), 2591 g mol(-1), and 1.196; 1736 g mol(-1), 2509 g mol(-1), and 1.445, respectively. Also, differential thermal analysis (DTA) and thermo gravemetric analyses (TGA) were shown to be stable of oligo-2-hydroxyphenylbenzaldimine against thermo-oxidative decomposition. The weight loss of OHPBA was found to be 93.63% at 1000degreesC.Öğe The synthesis and characterisation of planar oligophenol with Schiff base substitute(Elsevier Science Sa, 2002) Kaya, İsmet; Demir, Hacı Ökkeş; Vilayetoğlu, Adalet R.In this study, the oxidative polycondensation reaction conditions of 2-p-tolylazomethinephenol (TAP) with air oxygen and sodium-hypochloride (NaOCl) were studied in an aqueous alkaline medium between 50 and 90 C. The structure and properties of the products were studied by chemical and spectra analyses. TAP was converted to ditrimers (15-67%) by oxidised in an aqueous alkaline medium. The number average molecular weight (M), mass average molecular weight (M-w,) and polydispersity index (PDI) values were found to be 6780, 7660 and 1.13, respectively. A part of the azomethine (-CH=N-) group oxidised to carboxylic group (-COOH) during the polycondensation reaction. Thus, reaction product which is oligo-2-p-tolylazomethinephenol (OTAP), involves tolylazomethine and carboxylic (-COOH) (0.5-20%) groups. Besides, oligomer-metal complexes of OTAP with Cu(II), Zn(II), CO(H) and Pb(II) were synthesised and the structure and properties were studied. Antimicrobial activities of the oligomer and its oligomer-metal complexes have been tested against L. monocytogenez, Bacillus brevis, P. vulgaris, E. coli, B. megaterium, M. luteus, B. cereus, K. pneumoniae, M. smegmatis, S. thermophilus, S. aureus, E. aeroginosa and Torulopsis holmii. Also, DTA and TG analyses were shown to be stable for OTAP and its oligomer-metal complexes against thennooxidative decomposition. Published by Elsevier Science B.V.
