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Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2011, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2011, Günümüzde protein ve peptit yapısındaki ilaçlar çok önemli tedavi edici ilaçlar olarak geliştirilmektedir. Bu tip ilaçların insan vücuduna verilmesinde en önemli engel, protein ve peptit yapısının mide ortamı asitliğinde dayanıklı olmayıp kolaylıkla bozunabilmesidir. Bu nedenle protein yapısındaki ilaçlar klasik olarak vücuda injeksiyon yoluyla verilmektedir. Ancak oral yolla ilaç alımının injeksiyon yoluyla ilaç alımına göre kolaylığı ve kullanıcı açısından istenilirliği son yıllarda protein yapısındaki ilaçların oral olarak etkin bir şekilde vücuda verilmesi konusunda araştırmaları yoğunlaştırmıştır. Protein yapısındaki ilaçların vücutta etkin olması, kontrollu salımının yapılacağı bir ortamın içine kapatılması, mide asitliğinden etkilenmeden alkali barsak ortamına geçmesi ve bu ortamda kontrollu bir şekilde salınması ile gerçekleştirilebilir. Bu çalışmamızda protein olarak seçilen sığır serum albüminin (BSA), aljinat jel küreleri içine hapsedilerek yapay olarak hazırlanan mide ve bağırsak sıvısı ortamına kontrollu salımı incelenmiştir. BSA’nın aljinat küreleri içine ilave edilen kilin ara yüzeylerine girip nanokompozit bir yapı oluşturulması sağlanıp, BSA nın salım hızı yavaşlatılmış ve BSA’nın bozunmadan ve düşük salımla mide ortamından geçip, bağırsak ortamında kontrollu salımını gerçekleştirecek deneysel parametreler saptanmıştır., Protein based drugs and their applications are developing research areas nowadays. Most common problem in such drugs is denaturation of protein and peptide structure in acidic gastric media. In order to avoid this, protein and peptide based drugs are applied by injection. However oral applications are more convenient and demanded by patients. Oral usage of protein and peptide based drugs require an encapsulation, directly passage through stomach and a release in basic intestinal track. In the present work, a model protein, bovine serum albümin (BSA), is encapsulated in clay-modified alginate gel beads. Release behavior, swelling kinetics and other properties of these beads are investigated. It is shown that BSA molecules are placed between clay layers, forming a nanocomposite structure, and this led suggested formula to be more efficient in encapsulation of BSA. Moreover, this also provided slower release and lower losses in gastric fluid., Yüksek Lisans, M.Sc.

The 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.

Cobalt oxide nanoparticles were synthesized by thermal decomposition of cobalt alginate biopolymer gel at 350 oC and 450 oC. Because of its attributes like gel responsiveness, non toxic, ion crosslinking and low cost, alginate was used to produce Cobalt oxide nanoparticles. The gel beads were prepared and the results were characterized. The confirmation of the cobalt oxide, graine size distribution and also the crystallite size was carried out using XRD analysis, TEM analysis was done to determine the particle size. The results shows the size of the cobalt oxide nanoparticles to be 32nm, GSD was also calculated using th full width at 1/5 and 4/5 of maximum of the XRD peaks. EDS coupled with SEM analysis shows the elements present in the CoNPs with their percentage.

A wound is a break or tears in the continuity of the skin or mucosa epithelial lining caused by physical or thermal trauma. Wound dressings need strong mechanical capabilities, good antibacterial qualities, and, more importantly, natural material components. This study combined the advantages of alginate and carboxymethylcellulose crosslinked with zinc. Films were distinguished by Fourier transform infrared spectroscopy (FTIR), light transmittance, scanning electron microscopy (SEM), swelling experiments and water vapour transmittance tests. The antimicrobial and physical properties of the films were compared with similar studies. Wound dressing based on zinc crosslinked alginate and carboxymethyl cellulose films gained antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Wound dressing based on zinc crosslinked alginate and carboxymethyl cellulose films can be ultraviolet-protecting and antibacterial wound dressings.

Biopolymer-nanoparticle composites are one of the emerging materials in the interdisciplinary applications for biomedical science, mechanical engineering and chemistry. This kind of materials exhibit very useful properties such as biocompatibility, high surface area, and drug entrapment. Especially for biological applications, swelling properties of the materials are one of the very important parameters. Sustained release and diffusion parameters of the biochemical agents and drugs are related to the absorption of the liquid which the nanocomposite matrix is in contact with. In this experimental study, the swelling parameters of cerium oxide-calcium alginate nanocomposites in three different liquid medium, namely pure water, isotonic sodium chloride solution, and simulated gastric fluid is investigated. Here, nanoparticles of cerium oxide are synthesized by cerium-alginate biopolymer route and then dispersed in sodium alginate solution in order to achieve a homogeneous dispersion. Due to the origin of the nanoparticles, to the best of our knowledge, this kind of study is also reported for the first time in the literature.

Alginate biopolymer has several applications-especially in biological fields such as drug release, tissue engineering, and wound dressing, due to its biodegradable, biocompatible, and non-toxic properties. Copper ion has been used in previous wound dressing studies for its antimicrobial property. In this thesis study, firstly, copper crosslinked alginate beads (Alg) were prepared using the quasi-cryogelation method. Their swelling profile was investigated since alginate forms hydrogel in the presence of divalent cations. Swelling experiments were performed in two solutions, pure water and 0,9% (w/v) isotonic. Swelling ratios were found as 29% in purified water and 24% in an isotonic solution. Secondly, Alginate beads were modified by the quasi-cryogelation method. In this way, it was aimed to improve the swelling degree with the increasing porosity of beads. The swelling degree of Quasi-Alg beads was found as 295% in pure water and 260% in an isotonic solution. This study exhibits a method to increase the swelling ratio of hydrogels. Since the swelling ratio is essential for drug release to effectively release the drug or for wound dressing films to supply enough moisture to wound, Quasi-Alg beads may comprise a basis for such applications.

Annealing is a process that often results in aggregation of the crystallite particles and therefore an increase in crystallite size is often observed. In this study, the behavior of biopolymer-assisted synthesized cerium oxide nanoparticles under the influence of annealing is investigated. Cerium (III) alginate hydrogels were thermally decomposed at 450 °C to synthesize cerium oxide nanoparticles, which is reported in literature as a green method and results in surface functionality of the nanoparticles. The particles were annealed at two different temperatures (600 and 800 °C) for 2, 4 and 8 hours. X-ray diffraction was used to characterize the powder samples for observing the average crystallite sizes, which were calculated using Scherrer’s equation. Additionally, the grain size distribution of the nanoparticles is also studied by a semi-numerical method based on diffraction patterns. Results indicate that the annealing increases the sample size 2 to 4 times, which can be useful for designing the average crystallite size in advanced studies such as optics and drug delivery.

Erim, Fatma Bedia/0000-0001-9406-6681 WOS:000511042000001 Cerium 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.

2-s2.0-85044758674 Quasi-cryogelation technique is a simple yet effective technique for improving the adsorptive efficiency of biopolymer-based adsorbent materials. In this work, a biopolymer-based adsorbent material, graphene oxide alginate quasi-cryogel beads are reported. Alginate biopolymer was crosslinked and frozen at ? 21 °C in order to obtain a gel with cryogel-like microstructure. Graphene oxide was included in the bead formulation in order to enhance the adsorptive characteristics. Beads were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and swelling experiments. Removal of the model cationic dye, methylene blue, was studied by batch adsorption method. It is found that the adsorption follows the Freundlich isotherm model and pseudo-first order kinetics with reaching an adsorption capacity of 122.26 mg/g in 60 min. Results indicate that the physisorption might be due to theinteractions between graphene oxide and methylene blue, in addition to electrostatic interactions. Moreover, quasi-cryogelation technique significantly improved the dye removal properties. © 2018, Springer International Publishing AG, part of Springer Nature.