Wool Keratin Research Articles

Wool cortical cell-based porous films

The aim of this work is to improve the select mechanical properties of keratin films for biomedical application by exploiting the hierarchical cell structure of wool fibers in a simple and green process. Bio-composite keratin films were prepared by ultrasonic irradiation of wool fibers soaked in clean water, have previously been swollen in mild alkali. The disruption of the fiber cell structure produced a suspension of cortical cells that was centrifuged and rinsed to remove part of the hydrolyzed keratin matrix, then cast into micro-structured porous films made of randomly oriented cortical cells stuck to each other by solidification of the matrix. The chemical and physical properties of the porous films were compared with those of compact films produced using the entire hydrolyzed keratin matrix. Reduction of the keratin matrix amount leads to an even micro-porous structure and improves the mechanical properties (ultimate tensile strength: 11.36 MPa; elongation at break: 3.18%), the moisture uptake and the thermal stability of the films. These properties, associated with other properties of wool keratin, which is naturally hydrophilic, non-burning, biodegradable and biocompatible, make the porous bio-composite keratin films simple and low-cost candidates for biomedical and biotechnology applications.

Microwave-assisted chemical-free hydrolysis of wool keratin

Wool fibers were submitted to “green hydrolysis” with superheated water in a microwave reactor, in view of the potential exploitation of keratin-based industrial and stock-farming wastes. The liquid fraction was separated by filtration from the solid fraction, which consists mainly of small fragments of wool fibers and other insoluble protein aggregates. The liquid fraction contains free amino acids, peptides and low molecular weight proteins, with a small amount of cystine and lanthionine, and has a different secondary structure when compared with keratins extracted from wool via reductive or oxidative methods. Cleavage of the cystine disulfide bonds without the use of harmful, often toxic, reductive or oxidative agents allows the extraction of protein material from keratin wastes, offering the possibility of larger exploitation and valorization.

Chemiluminescence from UVA–exposed skin: Separating photo-induced chemiluminescence from photophysical light emission

Several previous studies have reported luminescence emission from skin following exposure to UVA radiation in air. We show that UVA irradiation of biomaterials and polymers in oxygen, including bovine stratum corneum, followed by photon counting results in a complex emission due to a combination of photophysical processes together with photo-induced chemiluminescence (PICL). The photophysical processes include fluorescence, phosphorescence and charge-recombination luminescence. By irradiating materials in an inert atmosphere such as nitrogen and allowing photophysical light emission to fully decay before admitting oxygen, the weak photo-induced chemiluminescence generated via free radical reactions with oxygen can be separated and analysed. PICL emission from bovine stratum corneum is weaker than for wool keratin and bovine skin collagen, probably due to its higher water content, and the presence of the natural antioxidants ascorbate and tocopherol.

The Characterization of Porous Structure of Frozen Wool Keratin Membrane

Use the keratin liquid which solved from wool with urea and 2-mercaptoethanol to prepare wool keratin porous membrane at different concentration and frozen temperature. Observe the morphological structure of the membrane by SEM and analyze the SEM pictures. The experimental results indicate that the liquid concentration and frozen temperature are inversely proportional to the porous membrane aperture and porosity, but proportional to the porous membrane density.

Preparation of regenerated wool keratin films from wool keratin–ionic liquid solutions

AbstractThe regenerated wool keratin films were prepared from the wool keratin/ionic liquid solutions through water, methanol and ethanol as coagulation solvents in this article. It could be suggested from the results that [AMIM]+·Cl− ionic liquid has higher solubility for wool keratin fibers than [BMIM]+·Cl− ionic liquid. IR data showed the part of the disulfide bonds was broken during the dissolution. It could be seen from XRD data that the regenerated films exhibited a β‐sheet structure and the disappearance of the α‐helix structure. TGA curves indicated that the thermal stability of regenerated wool keratin films decreased slightly compared to nature wool fibers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and characterization of wool keratin/hydroxyapatite nanocomposite

Taking the inspiration from the biomineral, the wool keratin was selected to modulate the assembly of nanosized hydroxyapatite (HA) crystals via a coprecipitation method. A series of keratin/HA nanocomposite with different ratios were synthesized by adjusting the concentrations of keratin solutions and calcium phosphate and their final components were detected by thermogravimetric analysis (TGA). The transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed that keratin in the composite decreased the crystallinity of HA. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to examine the chemical and surface structure of the composites. In vitro biocompatibility results revealed that cells showed better viability on keratin/HA composites which have a ratio of organics and inorganics similar to that of natural bones.

Diffuse reflectance spectroscopy of fibrous proteins

UV-visible diffuse reflectance (DR) spectra of the fibrous proteins wool and feather keratin, silk fibroin and bovine skin collagen are presented. Natural wool contains much higher levels of visible chromophores across the whole visible range (700-400nm) than the other proteins and only those above 450nm are effectively removed by bleaching. Both oxidative and reductive bleaching are inefficient for removing yellow chromophores (450-400nm absorbers) from wool. The DR spectra of the four UV-absorbing amino acids tryptophan, tyrosine, cystine and phenylalanine were recorded as finely ground powders. In contrast to their UV-visible spectra in aqueous solution where tryptophan and tyrosine are the major UV absorbing species, surprisingly the disulphide chromophore of solid cystine has the strongest UV absorbance measured using the DR remission function F(R)(∞). The DR spectra of unpigmented feather and wool keratin appear to be dominated by cystine absorption near 290nm, whereas silk fibroin appears similar to tyrosine. Because cystine has a flat reflectance spectrum in the visible region from 700 to 400nm and the powder therefore appears white, cystine absorption does not contribute to the cream colour of wool despite the high concentration of cystine residues near the cuticle surface. The disulphide absorption of solid L: -cystine in the DR spectrum at 290nm is significantly red shifted by ~40nm relative to its wavelength in solution, whereas homocystine and lipoic acid showed smaller red shifts of 20nm. The large red shift observed for cystine and the large difference in intensity of absorption in its UV-visible and DR spectra may be due to differences in the dihedral angle between the crystalline solid and the solvated molecules in solution.

The Efficient Wool Keratin Dissolution Based on New Reductant

The dissolution of the wool keratin has a history of several decades, but the effective dissolution method has not been found yet. In this article, a novel reducing agent TCEP (Tris (2-carboxyethyl) phosphine) was used, which has a strong ability for selective reduction of disulfide bonds. With a joint use of sodium bisulfite, the wool dissolution has a great advantage in wool processing compared with previous methods; Through amino acid analysis, it was found that the content of the cysteine decreased significantly when using the TCEP as reducing agent, and the other amino acids did not change significantly, indicating that TCEP has high selectivity for reduction of disulfide bonds, and plays a significant role to maintain the molecular weight of keratin. The efficiency of dissolution was greatly improved; dissolution time was 4h, dissolution rate was 93.6%, keratin concentration was 10%, the yield of keratin with the molecular weight more than 3500 and more than 8000 were 80% and 72% respectively. By using SDS-PAGE, we can get that the main molecular weight of the keratin was 14000-20000.

Preparation and Characters of Wool Keratin Aqueous Solution

Wool fiber was dissolved with compound solvent(urea, β-mercapitoethanol and sodium dodecyl sulfate(SDS)) and stable keratin aqueous solution was prepared through filtration and dialysis. Dissolution rate under different conditions was disscused. The results showed that dissolution rate increased with the increase of dissolving temperature, reduction β-mercaptoethanol and assistant agent urea concentration and the addition of SDS. SDS PAGE showed the major molecular weight of the aqueous keratin solution was about 44.3KDa.

Keratin capped silver nanoparticles – Synthesis and characterization of a nanomaterial with desirable handling properties

We report for the first time the stabilization of silver nanoparticles in good yield, average diameter 3.5 nm, using wool keratin hydrolysates as stabilizers. The nanoparticles are extremely stable as a suspension and can be lyophilized into a powder and easily reconstituted in solvent with no change in spectral properties relative to the initial suspension. The nanoparticles interact with nitrogen and oxygen moieties of the keratin hydrolysates under the pH conditions used in the synthesis and appear to act as cross-linkers between adjacent chains. The product has excellent handling properties which we believe will make it a very attractive biocompatible coating/additive, providing prolonged antimicrobial efficacy to a wide variety of products such as textiles, plastics, paints, orthopedic devices and others.

Preparation and Characterization of Wool Keratin/PVA Blended Films

The method of extracting protein from wool was studied for the purpose of reusing the waste wool. The aqueous solution of wool keratin was prepared with Sodium Shlfide as reductive agent. In this paper, PVA was used to mix with keratin in different proportions. Both solutions were cast to obtain blended films. Scanning electron microscopy investigation showed that the surface of blended films was rough and uneven and the surface of the pure keratin film had small peridiole. FTIR analysis indicated that the secondary structure of the keratin was influenced by the blending ratios. Compared with wool fiber, the keratin film cast from aqueous solution showed a decrease in the amount of α-helix structure, while β-sheet and random coil conformations increased. When the keratin solution and PVA solution were blended in the ratios of 40:60, the film was flexible and rigid, and had good mechanical properties. This study encourages the further investigation of the applications of wool keratin films in the biomedical field, which could provide a new way to reuse various waste feathers.

Water sorption of nails treated with wool keratin proteins and peptides

Water has a considerable effect on human keratin fibres, such as nails, and is therefore crucial for their cosmetic performance. Wool proteins are mild, natural, biodegradable and are sustainably produced with multiple functionalities. They have a potential for use in the cosmetic and detergent markets. The effectiveness of two wool keratin ingredients in restoring the water sorption characteristics of nails was determined. Acetone treatment modified nail water sorption, resulting in an increase in water sorption capacity and in nail permeability. The application of keratin peptides and proteins to healthy and damaged nails improved water sorption properties, reducing permeability, especially in the case of wool keratin protein treatment.

Heat transfer in fractal channel network of wool fibre

Wool keratin fibre possesses an optimal configuration with tree-like hierarchical structure and with fractional dimensions of 1·618, the golden mean. Such hierarchical structure, compared with traditional parallel channel net, reveals excellent heat transfer capability.

Nano titanium dioxide on wool keratin as UV absorber stabilized by butane tetra carboxylic acid (BTCA): A statistical prospect

Photo yellowing of wool is one of the most important problems which have negative impacts on various aspects of wool prompting scientists to find a solution over the past decades. In this research the protective features of nano-titanium dioxide particles against UV on wool fabric were discussed and the color variations of wool samples after UV irradiation were measured and reported. It was shown that nano TiO2 is a suitable UV absorber and its effect depends on the concentration. Also, it was assumed that butane tetracarboxylic acid plays a prominent role as a cross-linking agent to stabilize the nano-titanium dioxide as well as a polyanion to maintain negative charges on the wool surface for higher nano particles absorption. Also the variables conditions were optimized using response surface methodology (RSM).

Restoring important hair properties with wool keratin proteins and peptides

In this work the effect on hair of two types of keratin samples obtained from wool, was investigated. Fiber surface changes were evaluated by contact angle measurements. The effectiveness of these keratin ingredients to restore the mechanical properties and the moisture content of the fibers was also determined. Modifications of hair properties due to some conventional chemical treatments were demonstrated with lower values of contact angle and detrimental effects on the mechanical properties. Application of keratin peptides and proteins to pretreated hair improved the fibers’ moisture content and their mechanical properties.

Photochemical crosslinking of soluble wool keratins produces a mechanically stable biomaterial that supports cell adhesion and proliferation

Keratins extracted from various "hard tissues" such as wool, hair, and nails are increasingly being investigated as a source of abundant, biocompatible materials. In this study we explored a recent photochemical method to crosslink solubilized wool keratoses, with the aim of producing a mechanically favorable biomaterial. Wool proteins were isolated by oxidizing the disulfides and extracting the resulting soluble keratoses. The α- and γ-keratose fractions were analyzed by liquid chromatography-mass spectrometry to identify their constituent proteins. Hydrogels were produced by covalent crosslinking of the α-keratoses via a photo-oxidative process catalyzed by blue light, a ruthenium complex, and persulfate. The presence of dityrosine crosslinks was demonstrated by high performance liquid chromatography and mass spectrometry analyses. The crosslinked α-keratose material had moderate tensile strength and elasticity, and high adhesive strength. The material displayed modest shrinking after crosslinking, however the shrinking could be prevented by crosslinking in the presence of 2.5% glycerol, resulting in gels that did not shrink or swell. Small solutes such as Tris and glycerol influenced the crosslink density and elastic modulus of the crosslinked material. The α-keratose was able to support adhesion and growth of NIH/3T3 fibroblasts in vitro. The fabrication of mechanically stable keratin biomaterials by this facile photo-crosslinking method may be useful for various tissue engineering applications.

The Bio-inspired Study of Homogeneous Composite Materials

Wool is the most popular natural material. In the textile industries, the release of a lot of waste wool fibers and their products lead to the idea of regeneration of wool keratin materials. However, the most significant limitation may be the poor fracture resistance of neat keratin films. Greater failure resistance can be achieved by fiber-reinforced matrix when compared to the matrix materials alone. In this article, the fibrils of wool were used as the reinforcements in composite films, which can meet the requirement of biocompatibility. The fibrils morphology was investigated, that is, plain fibrils and fractal-tree structure fibrils. Finite element analysis and tensile tests were used to conduct a direct study on the mechanical properties of composites. It was found that the branched fibrils lead to both higher strength and fracture toughness for the composites than the plain fibrils.

Enhancing Dye Adsorption of Wool Fibers with 1-butyl-3-methylimidazolium Chloride Ionic Liquid Processing

In this paper, 1-butyl-3-methylimidazolium chloride ionic liquid (IL) which has good solubility for wool keratin, was employed to treat the wool fibers. The characterization of IL treatment on the wool fibers was first investigated using scanning electron microscopy (SEM), the Allwörden reaction and X-ray diffraction (XRD) analysis. Then, the effect of the IL treatment on the wool adsorption properties for an acid dye was studied through the dyeing rate test. The IL treatment was proven to be an effective process for wool characterization. The scales of the IL-treated wool fibers were eroded and even dislodged when the treatment temperature was increased according to the SEM observations. The Allwörden reaction showed that the epicuticle of wool fibers was damaged and became incomplete after the IL treatment. XRD indicated that the IL treatments could cause the decrease in the degree of crystallinity of wool fibers. Furthermore, the adsorption and diffusion behaviors of the IL-treated wool samples showed that the ionic liquid modification could improve the sorption properties of the wool fibers as represented by the increases in the dyeing rate.

Enhanced Chondrogenic Responses of Human Articular Chondrocytes Onto Silk Fibroin/Wool Keratose Scaffolds Treated With Microwave‐Induced Argon Plasma

Silk fibroin (SF) is a natural, degradable, fibrous protein that is biocompatible, is easily processed, and possesses unique mechanical properties. Another natural material, wool keratose (WK), is a soluble derivative of wool keratin, containing amino acid sequences that induce cell adhesion. Here, we blended SF and WK to improve the poor electrospinability of WK and increase the adhesiveness of SF. We hypothesized that microwave-induced argon plasma treatment would improve chondrogenic cell growth and cartilage-specific extracellular matrix formation on a three-dimensional SF/WK scaffold. After argon plasma treatment, static water contact angle measurement revealed increased hydrophilicity of the SF/WK scaffold, and scanning electron microscopy showed that treated SF/WK scaffolds had deeper and more cylindrical pores than nontreated scaffolds. Attachment and proliferation of neonatal human knee articular chondrocytes on treated SF/WK scaffolds increased significantly, followed by increased glycosaminoglycan synthesis. Our results suggest that microwave-induced, plasma-treated SF/WK scaffolds have potential in cartilage tissue engineering.

Utilization of Water-Soluble Protein from Wool Keratin in the Additive Finish of Textiles

Utilization of Water-Soluble Protein from Wool Keratin in the Additive Finish of Textiles