Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 32Citation - Scopus: 33Characterization of Silk Fibroin/Hyaluronic Acid Polyelectrolyte Complex (pec) Films(Springer Verlag, 2008) Malay, Özge; Yalçın, Dilek; Batıgün, Ayşegül; Bayraktar, OğuzThis study aimed the characterization of the films casted from the aqueous mixtures of the pH induced complexes between silk fibroin (SF) and hyaluronic acid (HA). The insoluble and transparent films were subjected to scanning electron microscopy (SEM) analyses to show the morphological changes. Thermal analysis of complex films was determined by a differential scanning calorimeter (DSC). The changes in the crystalline state were monitored by X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). It was shown that the complexation between HA and SF was dominantly induced by pH. It was shown that the complex films comprised mixtures of crystalline and non-crystalline regions.Article Citation - WoS: 72Citation - Scopus: 87Adsorption of Olive Leaf (olea Europaea L.) Antioxidants on Silk Fibroin(American Chemical Society, 2007) Bayçın, Deniz; Altıok, Evren; Ülkü, Semra; Bayraktar, OğuzThe adsorption isotherms of oleuropein and rutin were evaluated at different temperatures, pH values, and solid/liquid ratios. The experimental data of adsorption isotherms were well fitted to a Langmuir model. The maximum adsorption capacities were determined as 108 mg of oleuropein/g of silk fibroin and 21 mg of rutin/g of silk fibroin. After adsorption of oleuropein and rutin, the antioxidant capacity of silk fibroin increased from 1.93 to 3.61 mmol of TEAC/g. Silk fibroin also gained antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae after adsorption of olive leaf antioxidants. In a desorption process, 81% of rutin and 85% of oleuropein were removed from the adsorbent surface in 70% aqueous ethanol solution. Consequently, silk fibroin was found to be a promising biomaterial for the production of functional food or dietary supplements and for the purification of oleuropein and rutin from olive leaf extracts.Article Citation - WoS: 68Citation - Scopus: 70Complex Coacervation of Silk Fibroin and Hyaluronic Acid(Elsevier Ltd., 2007) Malay, Özge; Bayraktar, Oğuz; Batıgün, AyşegülThis study aimed to investigate the pH-induced complexation of silk fibroin (SF) and hyaluronic acid (HA). SF-HA complex coacervation was investigated by monitoring turbidity of the SF-HA system under slow acidification. Gravimetric analysis was performed to determine the yield of complex coacervation and viscosity of the system was measured to study the formation of the complexes at different pH values. The influences of total biopolymer concentration and biopolymer weight ratio on complex coacervation were examined during the analyses. Formation of the complexes was evidenced by the minimum viscosity and the maximum turbidity observed in the system. SF-HA complexes were formed within the pH-window of 2.5-3.5 regardless of the total biopolymer concentration or biopolymer ratio. Complex coacervation of SF-HA showed a reversible behavior and coacervation could be handled even in excess amounts of the biopolymers, which pointed out a non-stoichiometric complexation.Article Citation - WoS: 106Citation - Scopus: 122Silk Fibroin as a Novel Coating Material for Controlled Release of Theophylline(Elsevier Ltd., 2005) Bayraktar, Oğuz; Malay, Özge; Özgarip, Yarkın; Batıgün, AyşegülThe aim of this study was to explore potential use of the silk fibroin (SF) as an aqueous coating material for theophylline tablets. We have examined the film forming and coating properties of heat-treated fibroin, SF solution having different amounts of polyethylene glycol (PEG) and 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDC) cross-linked SF. Heat-treated SF material possessed a brittle structure, which resulted in poor film forming and coating properties. The optimum PEG amount in SF solution was determined as 17% (by weight) for an acceptable film forming and zero order release profile. EDC cross-linked SF has shown a very good film forming and coating property with a potential for sustaining the drug release from coated theophylline tablets. Dissolution data for coated theophylline tablets were analyzed using Ritger and Peppas equation to describe the mechanism of drug release. Drug release from the EDC coated tablets followed zero-order kinetics. Release rate constants were found to be 0.26, 0.19, 0.16% min-1 for single-coated, double coated, and triple coated tablets, respectively. These results clearly demonstrated that silk fibroin has high utility as a novel aqueous coating material for controlled release products.