Yazar "Sezer, Selda" seçeneğine göre listele
Listeleniyor 1 - 11 / 11
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Characterization and evaluation of the antimicrobial properties of algal alginate; a potential natural protective for cosmetics(Marmara Univ, 2022) Sayin, Selin; Depci, Tolga; Naz, Mehmet; Sezer, Selda; Karaaslan, Merve Goksin; Aras, Aycan; Ugur, SinemSargassurn vulgare was sampled by free dives in Iskenderun Bay, Hatay, Turkey, in September 2018. Sargassum vulgare is a material with high economic value because it has compounds that can be used in medical applications such as alginic acid and at the same time it contains carbohydrates and vitamins. Alginates were extracted with a sequential extraction protocol from Sargassum vulgare. Structural characterization of alginate obtained from Sargassum vulgare was determined by FT-IR spectrum, phase structure by XRD diffractometer, and surface morphology by SEM image. Within the scope of the study, alginate obtained from Sargassurn vulgare and herbal preservative 705 used in the field of cosmetics were compared. After pretreatment of Sargassurn vulgare with ethanol, alginate extraction was performed. Microorganisms of Pseudontonas aeruginosa, Staphylococcus aureus, Candida albicans, Escherichia soli, Aspergillus brasiliensis were used to examine the antimicrobial activity of the obtained alginate and showed that the contamination risk was tolerable for all microorganisms examined on the seventh day of incubation. Alginate obtained from Sargassum vulgare was found to be more effective than herbal preservative 705 at 0 hours. Pseudomonas aeruginosa, Staphylococcus aureus are microorganisms with the highest effect in the 0 hour. Since alginate obtained from Sargassurn vulgare is more effective on microorganisms in a shorter time than herbal preservative 705, it is predicted that it can be a product that can be used in the field of cosmetics.Öğe Comparison of ZnO doped different phases TiO2 nanoparticles in terms of toxicity using zebrafish (Danio rerio)(Pergamon-Elsevier Science Ltd, 2023) Sezer, Selda; Yucel, Aysegul; Turhan, Duygu Ozhan; Emre, Fatma Bilge; Sarikaya, MusaTitanium dioxide is used in many commercial and industrial areas such as paint, paper, cosmetics, textiles, and surface coating. The reasons for its use in such a wide area are its anti-corrosion and high stability. Although TiO2 is considered to be a low-toxicity material, research has been further expanded following the recognition of the possible carcinogenic effects of TiO2 in humans by the International Agency for Research on Cancer (IARC). The aim of this study is to compare the toxicity of TiO2 used in many fields in different phases. In the study anatase TiO2 synthesized by hydrothermal method and dual phase TiO2 (anatase and rutile phase) structures obtained by thermal conditioning were used and compared with commercially available TiO2. ZnO which has similar uses like TiO2 was also used and compared with 1% doped TiO2 in different phases in terms of toxicity. Zebrafish (Danio rerio, D. rerio), a freshwater fish, which is widely used in toxicity assessments was preferred in this study due to its small size, fast reproduction rate, low cost, physiological and molecular similarity with humans, and genetic predisposition. Experimental investigations showed that the highest death occurred in the low concen-trations of (10 ppm) ZnO doped rutile phase. 39% of the embryos died in the ZnO nanoparticle solutions pre-pared at low concentrations. The highest mortality at medium (100 ppm) and high (1000 ppm) concentrations were observed in the ZnO-doped rutile phase after 96 h. Similarly, the highest malformation was detected in the ZnO-doped rutile phase during the same period.Öğe Development of microbial chondroitin sulfate-based proton exchange membranes for microbial fuel cells(Elsevier Sci Ltd, 2024) Erenler, Sebnem A.; Unver, Tuba; Ozaslan, Bahar F.; Koytepe, Suleyman; Sezer, SeldaTechnological developments have led to a significant increase in energy demand, and thus the interest in alternative energy has increased in the same direction. For this reason, fossil fuel reserves and climate-based renewable energy sources were used as alternatives in energy production, but the desired success was not fully achieved due to the decrease in fossil fuel and climate changes, and a new alternative energy source was sought. This situation has made Microbial Fuel Cells (MFC), which can directly convert chemical energy, an important alternative to renewable energy, from organic waste into electrical energy with the help of microorganisms. Therefore, in this study, microbially obtainable chondroitin, which is a non-toxic, biocompatible organic molecule that will not disrupt the ecological balance, sulfate-based proton exchange membrane was prepared for the microbial fuel cell. For this, Chondroitin was synthesized by the microbial method, chondroitin sulfate was obtained by sulfation, and chondroitin sulfate membranes were prepared by cross-linking with sulfosuccinic acid at varying molar concentrations (0.2, 0.4, 0.6, and 0.8). Firstly, the structural characterization, thermal properties, and morphological features of the prepared 20 mm thickness membranes were investigated, and then the effects of parameters such as pH change, voltage, quaternization, internal resistance, and coulomb efficiency on microbial fuel cell performance were studied. The best result was found to be that of chondroitin sulfate cross-linked with 0.8 M sulfosuccinic acid, which had an internal resistance of 0.310 omega, a power density of 30 mW/m2, and a coulomb efficiency of 70 %. Additionally, proton conductivity was measured to be 0.9919 mS/ cm, and thanks to the proton conduction efficiency of the designed Microbial chondroitin sulfate membranes, it has been determined that it has an effective proton exchange membrane potential. These developments show that microbial chondroitin sulfate-based membranes may be an alternative candidate for microbial fuel cells.Öğe Hibrit polimerik malzemelerin sentezi, fizikokimyasal özelliklerinin incelenmesi ve diş protez malzemelerinde uygulamalarının araştırılması(İnönü Üniversitesi, 2014) Sezer, SeldaYüksek lisans tezi olarak sunulan bu çalışmanın amacı, diş hekimliğinde 1940'lı yıllardan beri kullanılan ve hala alternatifi olmayan poli(metil metakrilat) (PMMA) diş protezi kaide malzemelerinin mekanik dayanımını artırmak ve yeni hibrit polimerik malzemeler sentezleyerek diş protez kaide malzemesi olarak kullanılabilirliğinin araştırmasıdır. Bu amaçla PMMA'ın halloysit nanotüplerle (HNT) güçlendirilmesi, termal ve mekanik özelliklerinin iyileştirilmesi çalışmaları yapıldı; metilmetakrilat, glisidil metakrilat ve (3- aminopropil) trimetoksisilan bileşikleri ile yeni hibrit polimerik malzemeleri hazırlandı. Ayrıca PMMA-HNT nanokompozitlerinde organik ve inorganik fazlar arasında homojen dağılmayı sağlamak ve uyumlaştırma yapmak amacıyla halloysit nano tüplerinin yüzeyleri 3- (trimetoksisilil) propil metakrilat (Silan A-174) ile kimyasal olarak modifiye edildi. %1-7 arasında modifiye HNT içeren nanokompozitler 64×10×2,5 mm boyutlarında mufla kalıp içerisinde hazırlandı ve örneklerin Elastikiyet modülü ve yatay dayanıklılık testleri ile termal ve yapı analizleri yapıldı. %1-3 arasında modifiye HNT ile içeren nanokompozitlerin mekanik dayanımının HNT oranın artmasıyla arttığı ancak %3'ten sonra düşmeye başladığı gözlendi.Öğe pH duyarlı dendrimer bağlanmış polimerik malzemelerin hazırlanması ve biyomedikal alanda kullanımı(İnönü Üniversitesi, 2019) Sezer, SeldaBu tez çalıĢmasında kontrollü ilaç salım çalıĢmalarında kullanılmak üzere mikrokristalin selüloz (MKS) ve polivinil alkol (PVA) ana zincirine bağlı poliamidoamin (PAMAM) ve poliester (PEs) dendrimerler sentezlendi ve ülseratif kolit tedavisinde etken madde olarak kullanılan 5-aminosalisilik asit (5-ASA)'in değiĢik pH'larda salımı araĢtırıldı. 5–ASA etken maddesine sahip ilaçlar günde 6 defa ve toplamda günlük dozu 3–4 gram olmak üzere aktif ülseratif kolit tedavisinde ömür boyu alınması gereken ilaçlar arasındadır. Bu çalıĢmada 5–ASA'nın intestinal sisteminde uzun süreli kontrollü salımı sağlanarak günlük doz miktarının alım periyodunu uzatarak hasta konforunun sağlanması amaçlanmıĢtır. Bu amaçla, –NH2 fonksiyonel PAMAM ve –OH fonksiyonel poliester dendrimerler yakınsak ve ıraksak yöntemlerle MKS ve PVA ana omurgası üzerinde farklı jenerasyonlarda sentezlendi. 5–ASA'nın dendrimerlerin her bir jenerasyonunun kavitasyonlarında tutuklanan ve sindirim sisteminin mide, ince bağırsak ve kalın bağırsağın fizyolojik pH'larında (3,5; 7,4 ve 8,5) in-vitro koĢullarda salımı araĢtırıldı. Hem PAMAM hem de ester dendrimerlerden 5–ASA'nın salımı pH 3,5'da %50'nin altında iken pH'nın bazik bölgeye kaymasıyla arttığı görüldü. Dendrimerlerin jenereasyon sayısı arttıkça salınan 5–ASA miktarının da arttığı bulundu. Bunun nedeni, dendrimer jenerasyon sayısının artması bağlı olarak kavitasyonlarda tutuklanan 5–ASA miktarındaki artıĢtan kaynaklanmaktadır. pH'nın artmasıyla salımın artması ise 5–ASA'nın asit grubunun deprotonasyonu dolayısıyla misafir-ev sahibi arasındaki hidrojen bağlarının zayıflamasından kaynaklanmaktadır. ÇalıĢma kapsamında sentezlenen bileĢiklerin karakterizasyonları FT–IR, 1H NMR, TGA–DSC, SEM, XRD teknikleri ile 5–ASA salım çalıĢmaları ise UV-vis ile gerçekleĢtirildi.Öğe Preparation and Characterization of Amino-Functionalized Zeolite/SiO2 Materials for Trypsin-Chymotrypsin Co-immobilization(Springer, 2021) Dogan, Demet; Sezer, Selda; Ulu, Ahmet; Koytepe, Suleyman; Ates, BurhanInorganic supports have attracted increased attention in enzyme immobilization since they not only improve enzyme stability but also reduce the final cost of enzymatic reactions. Herein, we explored the suitability of the amino-functionalized zeolite/SiO2 materials to co-immobilize trypsin-chymotrypsin mixture. For this purpose, the trypsin-chymotrypsin mixture was co-immobilized on the amino-functionalized zeolite/SiO2 materials and the immobilization yield was 80.7 +/- 7.6%. The pre-support and its modification were characterized by several techniques. Besides, the charges of the materials were investigated by zeta potentials at pH 5.0. As expected, the zeta potentials shifted from - 24.4 to - 8.16 mV after amino functionalization. Following immobilization, whereas the optimum pH (9.0) was not changed, the optimum temperature shifted from 50 to 40 degrees C. On the other hand, the immobilized trypsin-chymotrypsin showed comparatively higher thermal stability and storage stability than the soluble trypsin-chymotrypsin. The kinetic parameters were also calculated, however, while no significant change was observed in V-max, K-m value increased, which means that the affinity of enzyme to the substrate decreased after immobilization. Most strikingly, the residual activity of immobilized trypsin-chymotrypsin was 58% after eight repeated cycles. In conclusion, the preliminary experiments inferred that the amino-functionalized zeolite/SiO2 particles can be suitable and helpful support for trypsin-chymotrypsin immobilization. GraphicÖğe Preparation and Characterization of Amino-Functionalized Zeolite/SiO2 Materials for Trypsin-Chymotrypsin Co-immobilization (Apr, 10.1007/s10562-021-03636-2, 2021)(Springer, 2021) Dogan, Demet; Sezer, Selda; Ulu, Ahmet; Koytepe, Suleyman; Ates, Burhan[Abstract Not Available]Öğe Preparation, characterization, and biocompatibility of chondroitin sulfate-based sol-gel coatings and investigation of their effects on osseointegration improvement(Taylor & Francis As, 2023) Pasahan, Aziz; Sevimli, Resit; Kivilcim, Nilufer; Acari, Idil Karaca; Erenler, A. Sebnem; Sezer, Selda; Durmat, H. TurgutIn this work, implants with enhanced antibacterial and surface properties besides mechanical, biological, and chemical properties were prepared with the replacement of traditional titanium and titanium alloys in the field of biomedical materials. Titanium substrates were coated with chondroitin sulfate (CS) containing (3-glycidoxypropyl)trimethoxysilane (GLYMO) and tetraethoxysilane (TEOS) based thin film using sol-gel technology. Chondroitin sulfate is a preferred material due to its characteristics antioxidative and osseointegresion properties besides its collagen-forming properties. Coated implants were morphologically elucidated with atomic force microscopy (AFM), and scanning electron microscopy (SEM). The structure of the chondroitin sulfate-containing films was investigated with Fourier Transform Infrared Spectroscopy (FTIR) and Energy Dispersive X-Ray Analysis (EDX) techniques. The obtained CS-based sol-gel surface coatings are thermally stable up to similar to 200 degrees C according to TGA and DTA analysis results. The biological and antibacterial properties of the coatings were also determined. The biocompatibility and osseointegration properties of the coatings developed within the scope of the study were, determined by in vivo studies on rats. According to biocompatibility results of CS/Sol-Gel coated surfaces, Cell viability (%) rates of CS-based coatings showed between 89 and 66%. According to the experimental data, it has been claimed that implants improved with antibacterial, stable, homogeneous, and biocompatible coatings can be used as a new alternative product for dental and orthopedic applications.Öğe Synthesis and characterization of whitlockite from sea urchin skeleton and investigation of antibacterial activity(Elsevier Sci Ltd, 2021) Yucel, Aysegul; Sezer, Selda; Birhanli, Emre; Ekinci, Tuba; Yalman, Emine; Depci, TolgaIn the present study, undoped whitlockite and ZnO doped-Whitlockite, which is the second most abundant inorganic material in bone structure, were synthesized from sea urchin skeleton. The obtained bioceramic ma-terials were characterized by XRD, FT-IR, and SEM and their antibacterial activities were determined using the inhibition zone diameters of Escherichia coli and Pseudomonas aeruginosa as gram negative bacteria and Staphylococcus aureus as gram positive bacterium after 24 h incubation. The characterization studies showed that nano size homogenous biocereamic whitlockite (Ca2.86Mg0.14(PO4)(2)) was synthesized from the sea urchin skeleton. After dopping process, the main structure of the whitlockite keeps stable, showing a dopping concentration-independent character. On the other hand, the peaks belonging to ZnO were started to seen in the XRD pattern with increasing the level of ZnO-concentration (after 7 %). All experimental results point out that the obtained whitlockites are viable nominate candidates for bioceramic materials and the results of antibacterial sensitivity prove the inhibitory effect towards Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus for ZnO-doped-whitlockite.Öğe Synthesis and Stimuli-Responsive Properties of Metallo-Supramolecular Phosphazene Polymers Based on Terpyridine Metal Complexes(Springer, 2021) Sezer, Selda; Koytepe, Suleyman; Gultek, Ahmet; Seckin, TurgayIn this study, terpyridine functionalized phosphazene based metallo-supramolecular polymers were synthesized by three step reaction method. In the first step, 4 '-(4-aminophenyl)-2,2 ':6 ',2 ''-terpyridine was synthesized with p-nitro benzaldehyde and 2-acetylpyridine. Then, the monomer containing six terpyridine (TPY) units attached to the phosphazene was prepared from 4 '-(4-aminophenyl)-2,2 ':6 ',2 ''-terpyridine and hexachlorocyclotriphosphazene by a condensation reaction. Finally, metallo-supramolecular phosphazene polymers were synthesised with these TPY functional phosphazenes and different transition metal ions (Cu, Co, Ni, and Zn ions). Prepared metallo-supramolecular polymers containing phosphazene unit were investigated by elemental analysis, different spectroscopic methods, energy dispersive X-ray spectrometry (EDX) and thermal analysis techniques. The stimuli-responsive, optoelectronic and spectroscopic properties of the synthesised metallo-supramolecular phosphazene polymers were investigated for external effects with UV-Vis spectroscopy and electro-analytic techniques. In addition, competitive ligand effect on these metallo-supramolecular polymers was examined with ethylenediaminetetraacetic acid (EDTA). The resulting metallo-supramolecular polymers containing phosphazene unit show very fast stimuli-responsive properties, such as 3 s. they also showed a single reversible redox structure resulting from the bonding of homometallic segments to polymer chain. In addition, they showed d-pi transition (in the range of lambda = 330-550 nm) depending on the metal (Co, Ni and Zn) ion forming the supramolecular structure. The addition of competing EDTA ligands caused the degradation of metallo-supramolecular polymer structures. These metallo-supramolecular phosphazene polymers are a good alternative smart material for opto-electronic, electrochromic, photochromic and intelligent material applications.Öğe Synthesis of Phenanthroline-Functionalized Phosphazene Based Metallosupramolecular Polymers and Their Stimuli-Responsive Properties(Springer, 2018) Seckin, Turgay; Sezer, Selda; Koytepe, SuleymanA series of phenanthroline-functionalized phosphazene based metallo-supramolecular polymers (PFP-MSP) was synthesised using a two-step reaction strategy. In first step, three phenanthroline unit containing monomer (PFP-M) was prepared from 5,6-dihydroxy-1,10-phenanthroline and hexachlorocyclotriphosphazene by condensation reaction. Then, this PFP-M was reacted with different metal ion salts (Co, Ni, Cu, Fe, Eu, La, Tb, Lu ions) and resulting for the metallo-supramolecular polymers bearing phosphazene structure. Obtained PFP-MSPs were characterized by spectroscopic analysis, elemental analysis, Scanning electron microscopy measurement and SEM-energy dispersive X-ray spectrometry techniques. Stimuli responsible and opto-electronic properties of synthesized PFP-MSPs were also studied for different external stimulating factors, such as electrochemical or the addition of competitive complexing ligands by UV-Vis spectroscopy and electroanalytic techniques. As a result, prepared PFP-MSPs are good alternatives for photochromic, electrochromic, opto-electronic and smart material applications.
