İpek fibroini farklı formlarda elde edebilmek için (film, fiber, sünger vs. ), fibroinin uygun çözücüler içinde çözünmesi

To be able to obtain silk fibroin in different forms (film, fiber, sponge etc.), fibroin should be dissolved in suitablesolvents. Different solvents are used for this process. Very few of the studies in the literature were investigated on the effects of thesolvent system on the structure of the final product. This work aimed to fulfil this deficiency. For this reason, the main purpose of thiswork is to investigate the effect of different solvents on the obtained structure of fibroin / Polyvinyl Alcohol (PVA) compositesponges. Since this study’s final goal is to use the obtained composite sponges as a wound dressing, this presented work is the firstpart of the planned study that mainly consists of preliminary preparation steps. Fibroin / PVA composite sponges were obtained byusing lyophilisation (freeze drying) method in this work. Silk fibroin based sponges with high porosity were produced by employingthis technique. In this preliminary study, first the effects of different solvents that are used in the dissolution of silk fibroin on thegeneral structure of the obtained material and the composite structures that are formed by mixing with PVA were investigated. Then,produced composite sponge structures were characterized by using Scanning Electron Microscopy (SEM), Fourier Transform InfraredSpectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) methods. When the composite sponge structures, obtained in Calcium Chloride (CaCl2)-Ethanol-H2O, were examined, it was observed that the secondarystructure was dominated mainly by β sheet. The FTIR results showed that the Amide I and Amide II bands had changes in theirlocation and values after mixing with PVA. These results demonstrated that the interaction between fibroin molecules and PVAmolecules is quite strong. The silk fibroin, dissolved in Lithium Bromide (LiBr), mainly consisted the random coil structures and thestructure had not transformed into a β sheet conformation during the formation of the composites, which affected the ratio of thecrystal structure to the amorphous structure and thermal stability of the composite sponges. The thermal properties of the materialwere analyzed using TGA and DSC. In summary, when the fibroin solution, obtained by dissolving fibroin in the solvent system ofCaCl2-Ethanol-H2O, with the fibroin solutions, obtained by dissolving fibroin in the solvent system of LiBr are compared, it is foundthat their secondary structural conformation and morphologies were different and the fibroin structures that were obtained fromCaCl2-Ethanol-H2O solvent system formed more stable and strong complexes with PVA.