Keratin from wool fibers was extracted with different extraction methods, for example oxidation, reduction, sulfitolysis, and superheated water hydrolysis. Different samples of extracted keratin were characterized by molecular weight determination, FT-IR and NIR spectroscopy, amino acid analysis, and thermal behavior. While using oxidation, reduction, and sulfitolysis, only the cleavage of disulfide bonds takes place; keratin hydrolysis leads to the breaking of peptide bonds with the formation of low molecular weight proteins and peptides. In the FT-IR spectra of keratoses, the formation of cysteic acid appears, as well as the formation of Bunte salts (–S–SO3–) after the cleavage of disulfide bonds by sulfitolysis. The amino acid composition confirms the transformation of amino acid cystine, which is totally converted into cysteic acid following oxidative extraction and almost completely destroyed during superheated water hydrolysis. Thermal behavior shows that keratoses, which are characterized by stronger ionic interaction and higher molecular weight, are the most temperature stable keratin, while hydrolyzed wool shows a poor thermal stability.

The interest towards microcapsules based on non-toxic, biodegradable and biocompatible polymers, such as proteins, is increasing considerably. In this work, microcapsules were prepared using water soluble keratin, known as keratoses, with the aim of encapsulating hydrophilic molecules. Keratoses were obtained via oxidizing extraction of pristine wool, previously degreased by Soxhlet. In order to better understand the shell part of microcapsules, pristine wool and obtained keratoses were investigated by FT-IR, gel-electrophoresis and HPLC. Production of the microcapsules was carried out by a sonication method. Thermal properties of microcapsules were investigated by DSC. Microencapsulation and dye encapsulation yields were obtained by UV-spectroscopy. Morphological structure of microcapsules was studied by light microscopy, SEM, and AFM. The molecular weights of proteins analyzed using gel-electrophoresis resulted in the range of 38-62kDa. The results confirmed that the hydrophilic dye (Telon Blue) was introduced inside the keratoses shells by sonication and the final microcapsules diameter ranged from 0.5 to 4µm. Light microscope investigation evidenced the presence of the dye inside the keratoses vesicles, confirming their capability of encapsulating hydrophilic molecules. The microcapsule yield and dye encapsulation yield were found to be 28.87±3% and 83.62±5% respectively.

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