Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Development of hydrogels via photocrosslinking of wool proteins(01. Izmir Institute of Technology, 2024) Yakar, İrem; Top, AybenYüksek su emme kapasitesine ve doku benzeri özelliklere sahip hidrojeller, yara iyileşmesi için ideal nemli bir ortam sağlamaktadır. Bu çalışma, yara iyileştirme uygulamaları için doğal bir protein olan oksitlenmiş keratin (KTS) ve sentetik bir polimer olan Pluronic F127 bazlı biyoaktif gallik asit (GA) ve karbon noktaları (CD'ler) içeren hibrit hidrojellerin sentezlenmesine odaklanmıştır. KTS ve F127'nin metakrilatlanmış formları (KTSMA ve F127MA) metakrilik anhidrit kullanılarak sentezlenmiş ve fonksiyonelleştirilmiş formlar spektr oskopik yöntemler kullanılarak doğrulanmıştır. KTSMA ve F127MA, kendi kendini destekleyen hidrojeller oluşturmak için Irgacure 2959 fotobaşlatıcı kullanılarak UV ışığı altında çapraz bağlanmıştır. Üç hidrojel hazırlanmıştır: K4 (%4 KTSMA), K7.5 (%7.5 KTSMA) ve KP7.5 (%4 KTSMA + %3.5 F127MA) ve bunların viskoelastik, şişme, bozunma ve morfolojik özellikleri belirlenmiştir. Hücre proliferasyon testleri, tüm hidrojellerin hücre büyümesini desteklediğini göstermiştir. KP7.5 hidrojelleri kararlı mekanik ve bozunma özellikleri sergilemiştir. Karbon noktalar kurkumin ve l-lizin kullanılarak sentezlenmiş ve S. aureus'a karşı ılımlı antibakteriyel özelliklere sahip olduğu gösterilmiştir. Karbon noktaların yapısal ve optik özellikleri karakterize edilmiştir. Çok işlevli hidrojeller, KPGA, KPCD ve KPGACD, GA ve CD'lerin KP7.5 hidrojeline dahil edilmesiyle elde edilmiştir. GA içeren hidrojeller, DPPH testi ile değerlendirildiği üzere kayda değer antioksidan aktivite sergilemiştir. Biyouyumlulukları göz önüne alındığında, bu hidrojeller yara iyileştirme uygulamalarında potansiyel kullanıma sahiptir.Master Thesis Development of Peg-Peptide Conjugate Based Curcumin Delivery Systems(01. Izmir Institute of Technology, 2022) Aydoğan, Gamze; Top, AybenIn this study, a drug delivery system based on Pluronic F127 and a peptide conjugate was proposed. The F127-peptide conjugate was prepared by the reaction between succinimidyl functionalized F127 (SC-F127) and peptide. SC-F127 was synthesized using disuccinimidyl carbonate and DMAP. Folic acid-functionalized F127 (FA-F127) was also prepared to obtain active targeting copolymers. Four peptides containing pH-responsive multiple histidines and endosome disruptive GFWFG domain were synthesized using the Fmoc procedure. H-Gly-2-ClTrt resin and Rink amide MBHA resin were used to synthesize side-chain-protected and deprotected peptides, respectively. 2-chlorotrityl resin failed in synthesizing the high-purity peptides with adjacent histidines in their sequences. Peptide-4 having a sequence of GGH6GFWFG, was prepared with acceptable purity using rink amide MBHA resin and was conjugated to SC-F127. Curcumin was loaded to F127 and F127-peptide using the thin film method with DCM solvent. Almost all curcumin was encapsulated into F127 micelles. However, the entrapment efficiency % of the F127-peptide micelles was ~86% due to the lower solubility of F127-peptide conjugate in DCM. Dynamic light scattering experiments were used to determine the stability and size distribution of the micelles. Number-based size distributions of both micelles indicated that a single peak between 10 and 30 nm was independent of pH. The peak position did not change upon incubating the micelles at 37oC up to a few days. Initially, intensity-based results of both samples indicate bidisperse populations at pH 5.0 and 7.4. Curcumin-loaded F127 micelles aggregated in the three days, as revealed by the formation of the third peak above 1000 nm independent of pH. Curcumin-loaded F127-peptide micelles, on the other hand, retain their stability for up to five days at neutral pH. For this sample, the third peak was observed only at pH 5.0 on days 2 and 5.Master Thesis Cation Exchange (ag+, Zn2+, Cu2+) Behavior of Natural Zeolites(01. Izmir Institute of Technology, 2001) Top, Ayben; Ülkü, SemraIn this study, clinoptilolite, most abundant zeolite present in nature, was proposed as a low cost antibacterial material. As a preliminary work, antibacterial activities of the original, Ag, and Zn forms of the clinoptilolite were investigated against several strains and compared to the commercial antibiotics. No antibacterial action was observed for the original clinoptilolite. Ag loaded clinoptilolite was found to be superior to the Zn-form against Proteus spp. and Pseudomonas aeruginosa.The original, Na, Ag, Zn, and Cu forms of the clinoptilolite samples were characterized by FTIR spectroscopy, thermal analyses (TGA, DTA, and DSC), and N2 physisorption studies. Specific attention was given in to the chemical analysis of the clinoptilolite by ICP-AES. Using the standard addition method, the respective idealized formulas of the original and Na-clinoptilolite based on 72 oxygen atoms in the unit cell were calculated as:(Na0.816 K2.070) (Ca1.060 Mg0.264) (Al5.653 Fe0.390) (Si30.084) O72. 20.023 H2O, and (Na4.763 K1.057) (Ca0.076 Mg0.094) (Al5.843 Fe0.221) (Si29.911) O72.17.049 H2O.In the FTIR spectra of the original and exchanged forms of the clinoptilolite, considerable shifts (from 3460 to 3494.8 cm-1) were observed in the band, which is formed due to the interactions of water molecules with the framework via hydrogen bonds. The positions of the other bands were not affected by cation exchange significantly. From the TGA curves, the water contents ranged between 14.31 and 11.00 % for the original and the cation-exchanged forms of the clinoptilolite. Mainly, two endotherms and one exotherm were obtained in the DTA curves. The first endotherm occurred up to about 150 oC, the second endotherm lied between 200 and 700 oC, and the exotherm was obtained at about 850 oC. Significant differences observed between the shapes of the DSC curves indicated that the cations control the dehydration behavior of the samples. N2 physisorption isotherms of five samples were all, Type IV with BET surface areas ranging between 34.97 and 46.76 m2/g.Ag, Zn and Cu ion exchange equilibria were investigated at 25 oC for both the original clinoptilolite and Na-clinoptilolite. In the former case, from the plateau of the isotherms cation exchange capacities were determined as 1.184, 0.439, 0.539 meq/g clinoptilolite for Ag+, Zn2+, and Cu2+ respectively. The major portion of the exchanges was contributed by Na+ and Ca2+. Distribution coefficient values indicated that at Ag, Zn and Cu ion exchange equilibria were investigated at 25 oC for both the original clinoptilolite and Na-clinoptilolite. In the former case, from the plateau of the isotherms cation exchange capacities were determined as 1.184, 0.439, 0.539 meq/g clinoptilolite for Ag+, Zn2+, and Cu2+ respectively. The major portion of the exchanges was contributed by Na+ and Ca2+. Distribution coefficient values indicated that at relatively low initial concentrations, the preference of the clinoptilolite for Zn2+ and Cu2+ was significant. At higher concentrations, higher distribution coefficients were obtained for Ag+ compared to Zn2+ and Cu2+. Langmuir and Freundlich models were applied for each equilibrium data. For Zn2+ and Cu2+ exchanges, Langmuir model gave better correlation and Freundlich model fitted experimental data slightly better in the case of Ag+ exchange.Equilibrium isotherms for Ag+-Na+, Zn2+-Na+, and Cu2+-Na+ pairs were investigated. Silver exchange isotherm lied above the diagonal over the whole composition range. For zinc and copper exchanges, the isotherms were above the diagonal up to equivalent fractions of exchanging ion in solution phase (As) at about 0.2. While full exchange was attained for silver, partial exchanges were obtained in the case of zinc and copper. The standard free energy of exchange values were found as .6.0, 2.03 and 3.09 kj/equiv for Ag+-Na+, Zn2+-Na+, and Cu2+-Na+ pairs respectively. From these values selectivity sequence was obtained as Ag+ > Na+ > Zn2+ > Cu2+.Consequently, by considering the preliminary antibacterial activity results, specific cation exchange capacities, and selectivity sequence of the clinoptilolite, Ag-clinoptilolite seemed to be promising antibacterial material. The results of the current study compared to the literature data pointed out that cation exchange behavior of the clinoptilolite is dependent on its original cationic composition. Therefore, it is necessary to carry out specific studies on representative samples from the deposit before any practical application.