Keratin Based Material For Perspective Bio-Application

Keratin has natural characteristic for applying in biomaterial field as a biocompatible matrix like tissue regeneration, proliferation, and cell adhesion or drug career in the shape of microcapsules or microsphere. Because of the amino acid inherent structure, keratin extraction needs to be well designed to meet the particular requirement for applying in desired applications such as integrate with different molecules, drug releases, wound healing or biocompatible film. Keratinous sources such as wool, feathers are valuable by-products that abundantly present in nature. Although wool has valuable material in especially in textile industry, massive amount of low-grade wool cannot be utilized in textile and inevitably end up as a waste stream. Because of high cystine content of keratin, solubilization and extraction of keratin is a problematic process compared with other natural polymers such as collagen and chitosan. Using keratin in different level especially in large-scale requires understanding final properties of keratin which is strongly depends on producing procedure.. The interest towards drug career and microcapsules based on non-toxic, biodegradable and biocompatible polymers, such as proteins, is increasing considerably. In this work, keratin from wool fibers was extracted with oxidation, reduction, sulfitolysis, and superheated water hydrolysis methods. The effect of each method on obtained keratin properties are discussed and particularly reported how each extracted keratin influenced by the extraction process. In particular, all different samples of extracted keratin were characterized by molecular weight determination, FT-IR and NIR spectroscopy, amino acid analysis, and thermal behavior and the archived data were compared with reporting of previous studies with the emphasis of advantage and limitation of each extraction method. In the other part of the study, special attention are given to produce microcapsule and film from keratin-based material in line with biomaterial application. Microcapsules were prepared using water-soluble keratin, known as keratoses, with the aim of encapsulating hydrophilic molecules. The obtained keratin via oxidizing extraction of pristine wool, were utilized as shell part of the microcapsules which produced by sonication method. Production of the microcapsules was carried out by a sonication method. The microencapsulation and dye encapsulation yields were obtained by UV-spectroscopy. In addition, morphological structure of microcapsules was studied by light microscopy, SEM, and AFM and thermal properties of microcapsules were investigated by DSC. The molecular weights of proteins analyzed with gel-electrophoresis indicates the extracted keratoses has suitable molecular weight range for bio-application, and also the results confirmed that the hydrophilic dye (Telon Blue) was introduced inside the keratoses shells. The final microcapsules diameter ranged from 0.5 to 4 µm. One part of the experimental work is dedicated to producing keratin blend film with polyvinyl alcohol (PVA). PVA has been chosen because of its biocompatible and biodegradable properties which make this polymer as a promising candidate in the bio-field area. Blend of Polyvinyl alcohol (PVA) and keratoses were prepared with the aim of producing bio-compatible material proper for film and fiber structure mainly to improve the mechanical properties of obtained keratoses. Aqueous solution of keratoses and PVA was prepared for solution casting method. Blended films were characterized by, SEM, FT-IR spectroscopy and Differential scanning colorimetry and tensile properties

Practical ways of extracting keratin from keratinous wastes and by-products: a review

Renewable resources, biopolymers and bio-based materials are keywords of the sustainable development and environmental sustainability concepts. Biopolymers, the green alternatives to fossil fuel based polymers, have already found different feasible applications, from consumer goods to regenerative medicine. Keratin is the biopolymer contained in the skin derivatives and appendages and is one of the proteins with the most sophisticated architecture nature could produce. It is found in huge quantities in materials regarded as by-products or wastes with negative environmental impact but with high potential, for which it is desirable to develop valorization solutions. The increased interest towards biopolymers and renewable resources determined a large body of research and practical work concerning keratin extraction from different sources and regeneration into useful products. It is the aim of this paper to review the conventional chemical pathways and environmentally friendly alternatives for keratin solubilization as it regards the mechanisms, process parameters, characteristics of the obtained keratin forms, environmental and economical aspects. Current and possible applications of the solubilized keratin forms are also shortly reviewed

Development of Highly pH-Sensitive Hybrid Membranes by Simultaneous Electrospinning of Amphiphilic Nanofibers Reinforced with Graphene Oxide

: Nanofibrous-based pH sensors have shown promise in a wide range of industrial and medical applications due to their fast response time and good mechanical properties. In the present study, we fabricated pH-sensitive sensors of nanofibrous membranes by electrospinning polyurethane (PU)/poly 2-acrylamido-2-methylpropanesulfonic acid (PAMPS)/graphene oxide (GO) with indicator dyes. The morphology of the electrospun nanofibers was examined using scanning electron microscopy (SEM). The effect of hydrophilic polymer ratio and concentration of GO on the sensing response time was investigated. The sensitivity of the membranes was studied over a wide pH range (1−8) in solution tests, with color change measured by calculating total color difference using UV-vis spectroscopy. The membranes were also subjected to vapor tests at three different pH values (1, 4, 8). SEM results show the successful fabrication of bimodal fiber diameter distributions of PU (mean fiber diameter 519 nm) and PAMPS (mean fiber diameter 78 nm). Sensing response time decreased dramatically with increasing concentrations of PAMPS and GO. The hybrid hydrophobic/hydrophilic/GO nanofibrous membranes are capable of instantly responding to changes in solution pH as well as detecting pH changes in chemical vapor solution in as little as 7 s

Preparation of keratin-based microcapsules for encapsulation of hydrophilic molecules

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 38–62 kDa. 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 4 µm. 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

Physicochemical properties of keratin extracted from wool by various methods

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

Effect of selenium on growth performance and blood parameters of Holstein suckling calves

This experiment was conducted to evaluate and compare the effects of inorganic and organic selenium sources with inorganic and organic carriers on growth performance, starter feed intake, blood parameters, and the concentration of glutathione peroxidase in the blood of suckling Holstein calves. To this objective, 40 suckling Holstein calves (38.47±2.52 kg average birth weight) at 7 days of age were selected and randomly divided into four experimental groups (10 replicates). The experimental groups included control (without selenium supplement), inorganic selenium (supplemented with sodium selenate), organic selenium with inorganic carriers and, organic selenium with organic carriers. The results show that the supplementation of selenium significantly increased the glutathione peroxidase enzyme concentration (P<0.01) and can significantly reduce the concentration of plasma cholesterol (P<0.01). However, there was no significant effect of selenium supplementation on serum glucose, plasma total protein, triglyceride, and urea nitrogen concentrations. Also, none of the treatments had a significant effect on growth performance and starter feed intake