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Near infrared spectra of (a) wool, (b) keratoses, (c) kerateine, (d) sulfo-kerateine, (e) hydrolyzed keratin.
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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, reducti...
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... Sustainability in the wool-waste handling may occur by the exploitation of the products yield after hydrolysis of wool under certain thermochemical conditions, and in applications that use the keratin biopolymer, extracted from fibers by chemical solubilisation [7]. Keratin is found in various sources in nature, equating to more than 5000,000 ton/year and is available from textile industries, butchery, and breeding [35]. The key-point that attracted us in this research is that keratin can also be used to produce novel adhesives so to remove formaldehyde and other volatile organic compounds (VOC) from the environment [35]. ...
... Keratin is found in various sources in nature, equating to more than 5000,000 ton/year and is available from textile industries, butchery, and breeding [35]. The key-point that attracted us in this research is that keratin can also be used to produce novel adhesives so to remove formaldehyde and other volatile organic compounds (VOC) from the environment [35]. Thus, keratin hydrolysis products may react further to form coatings to be induced to the wood industry where HCHO is suspicious and no more desirable. ...
... However, the approach ought to follow environmentally-friendly treatments [25,26] too, regarding the employment of severe chemicals or energy consumption. Water is the desirable solvent, for example, keratin from waste greasy wool hydrolyzed with superheated water has been used for the preparation of organic fertilizers, due to the rich nitrogen content [35]. ...
... s0075 26.7.6 Biomedical application p0235 Wool keratin has low toxicity, increased availability, biodegradability, and biocompatibility, as well as physicochemical features and intrinsic bioactivity [46À49]. Keratin from wool has been extracted using reduction [46,50], oxidation [51,52], sulfitolysis [51,53], superheated water hydrolysis [51] and enzymatic hydrolysis [54] methods. Green chemistry-oriented approaches such as ionic liquids and deep eutectic solvents have better prospects in wool keratin extraction. ...
... s0075 26.7.6 Biomedical application p0235 Wool keratin has low toxicity, increased availability, biodegradability, and biocompatibility, as well as physicochemical features and intrinsic bioactivity [46À49]. Keratin from wool has been extracted using reduction [46,50], oxidation [51,52], sulfitolysis [51,53], superheated water hydrolysis [51] and enzymatic hydrolysis [54] methods. Green chemistry-oriented approaches such as ionic liquids and deep eutectic solvents have better prospects in wool keratin extraction. ...
... s0075 26.7.6 Biomedical application p0235 Wool keratin has low toxicity, increased availability, biodegradability, and biocompatibility, as well as physicochemical features and intrinsic bioactivity [46À49]. Keratin from wool has been extracted using reduction [46,50], oxidation [51,52], sulfitolysis [51,53], superheated water hydrolysis [51] and enzymatic hydrolysis [54] methods. Green chemistry-oriented approaches such as ionic liquids and deep eutectic solvents have better prospects in wool keratin extraction. ...
Wool, a marvelous fiber obtained from sheep skin, has been used for textile making for many centuries. Wool is a protein fiber comprised primarily of keratin. Natural wool fiber has been widely used in textiles to make winter wear apparel, shawls, rugs, and carpets. The unique fiber structure and surface morphology offer unique properties to wool such as elasticity, resiliency, thermal insulation, and warmth. This chapter underpins such unique properties of wool and defines the prospects with reference to its properties along with the sustainability aspect. To this end, conventional wool processing and product manufacturing are briefly stated. The research interventions in the area of wool usage are reviewed. In recent years, there is great attention to using wool in diversified applications serving various industrial sectors. Wool products have promising prospects in biomedical, agriculture, packaging, construction/building, filtration, home furnishing, and automobile industries.
... Nonetheless, the -S-S-bonds in keratin molecules, along with hydrogen and ionic bonding [14], contribute to a robust spatial structure showing strong resistance to acid, alkali, and bio-enzymatic degradation [15,16], making dissolution in common solvents challenging [17,18]. Most conventional methods for keratin solubilisation utilise a system of mixed solvents, wherein each component disrupts various forces within keratin molecules to achieve dissolution. ...
Waste wool was subjected to dissolution using an ionic liquid solvent, 1-butyl-3-methylimidazole chloride salt ([Bmim]Cl), with lithium chloride (LiCl) as an additive. This study’s objective was to examine the impact of LiCl on keratin’s solubility in [Bmim]Cl and characterise the structure and properties of keratin post-dissolution and regeneration. The results indicated that LiCl exhibits efficient solubility in [Bmim]Cl, enhancing keratin dissolution. Investigations employing Infrared, XRD and small-angle X-scattering spectroscopy, along with SDS-PAGE, demonstrated a degradation of the α-helical keratin structure during the dissolution process. This was accompanied by a reduction in molecular weight; however, keratin retained its protein nature. Atomic force microscopy (AFM) results revealed that keratin could proliferate on the slide surface or establish a continuous film. An integrative analysis suggested that wool protein macromolecules could be deconstructed by [Bmim]Cl and LiCl actions, inducing minor structural alterations in wool. This study proposes a groundwork for future research into keratin’s adsorption behaviour on textile materials, without significantly modifying the wool keratin structure or function.
... Although the protein concentration shown in Figure 3A is higher in the case of sample HP200, apparently hydrolysis at a temperature of 200°C induces further hydrolysis of peptides the loss of high temperature sensitive amino acids (Bhavsar et al., 2016;Rajabinejad et al., 2017), as can be seen in Figure 1 B by the absence of bands for HP200 sample, and it also leads to an oxidation process, given by the brown colour of the hydrolysate, so these oxidation products may interfere with the methods used to determine protein content. The FTIR spectra showed that the keratin extracted at 150°C maintained the structural features found in the feathers (Figure 4). ...
Biowastes have emerged as a promising source for the production of value-added products, reducing the burden on landfills and promoting the concept of a circular economy. Chicken feathers, constituting a significant fraction of the poultry industry's waste stream, possess a robust protein structure composed mainly of keratin. Keratin is a biopolymer with unique properties, including high nitrogen content and slow degradation, making it an attractive candidate for various applications in agriculture and other fields. One of the main problems is the development of more eco-friendly methods for the efficient extraction of this biopolymer. The aim of this study was to compare the yield of keratin extraction from chicken feathers by three methods, alkaline, acidic and subcritical water and to characterize the keratin obtained by the most eco-friendly method, i.e., subcritical water. The subcritical water extraction is a promising alternative to the alkaline and acidic extractions, if proper optimization is carried out. We show that SDS-PAGE electrophoresis combined with FTIR analysis can offer valuable Information in this respect.
... First, based on the results of the amino acid analysis carried out on the keratoses by Rajabinejad et al., a multicomponent compound was created to simulate the C-Ker-film structure. 44 The results are described in Table 3. ...
... The oxidative procedure was applied for keratose extraction, as reported in the literature. 44 Briefly, wool (4 g) was dipped in a solution containing 2% peracetic acid (36−40% peracetic acid in an acetic acid solution) with a fiber-to-liquor ratio of 1:50 for 24 h at room temperature. Actually, 4 g of wool was dipped in 200 mL of peracetic acid in a flash. ...
Chronic wound diseases affect a large part of the world population, and therefore, novel treatments are becoming fundamental. People with chronic wounds show high iron and protease levels due to genetic disorders or other comorbidities. Since it was demonstrated that iron plays an important role in chronic wounds, being responsible for oxidative processes (ROS generation), while metalloproteinases prevent wound healing by literally "eating" the growing skin, it is crucial to design an appropriate wound dressing. In this paper, a novel bioactive dressing for binding iron in chronic wounds has been produced. Wool-derived keratose wound dressing in the form of films has been prepared by casting an aqueous solution of keratoses. These films are water-soluble; therefore, in order to increase their stability, they have been made insoluble through a thermal cross-link treatment. Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA) analyses clarified the structure and the properties of the keratose wound dressing films. The capability of this new biomaterial in iron sequestration has been investigated by testing the adsorption of Fe3+ by inductively coupled plasma-optical emission spectrometry (ICP-OES). The results suggest that the keratose cross-linked films can adsorb a large amount of iron (about 85% of the average amount usually present in chronic wounds) following pseudo-second-order kinetics and an intraparticle diffusion model, thus opening new perspectives in chronic wound care. Furthermore, the QSAR Toolbox was applied for conducting in silico tests and for predicting the chemical behavior of the C-Ker-film. All of the data suggest that the keratose bioactive dressing can significantly contribute to wound healing by mechanisms such as iron depletion, acting as a radical scavenger, diminishing the proteolytic damage, acting as a substrate in place of skin, and, finally, promoting tissue regeneration.
... lama South America coat 10-44 µm various colors, sometimes brown [17][18][19] alpaca South America coat 20-40 µm Grey, fawn white, black, café, etc. [17][18][19] vicuña Perù, Bolivia and Argentina undercoat 13-14 µm from golden to cinnamon [17,18] guanaco South America undercoat 16.5-24 µm light brown [17,18] yak China, Afghanistan, Nepal, and other Asian countries undercoat 15-20 µm dark brown [20] angora China coat 14-16 µm white [21] Wool and fine animal fibers have similar chemical, physical and histological characteristics, which is why their mixtures cannot be mechanically or chemically separated through solubility in selective solvents. They are composed of the protein keratin, which has a high sulfur content and strong disulfide bonds that render it insoluble in water and resistant to a variety of chemical agents [22]. ...
... In Figure 8, one-dimensional electrophoresis patterns of wool and different animal fibers are shown. We can see two bands at about 50 kDa corresponding to the low sulfur proteins from intermediate filaments in cortical cells, different bands in the range 28-11 kDa corresponding to high sulfur proteins extracted from cuticular cells, and bands at molecular weight below 10 kDa corresponding to high glycine and tyrosine proteins from the matrix from cortical and cuticular cells and embedding cortical cells [22]. ...
... In Figure 8, one-dimensional electrophoresis patterns of wool and different animal fibers are shown. We can see two bands at about 50 kDa corresponding to the low sulfur proteins from intermediate filaments in cortical cells, different bands in the range 28-11 kDa corresponding to high sulfur proteins extracted from cuticular cells, and bands at molecular weight below 10 kDa corresponding to high glycine and tyrosine proteins from the matrix from cortical and cuticular cells and embedding cortical cells [22]. Marshal et al. [110] demonstrated that by using two-dimensional electrophoresis, it is possible to distinguish between wool, mohair, camel and alpaca, mainly according to differences in high sulfur protein separation patterns. ...
The identification and quantitative determination of wool and fine animal fibers are of great interest in the textile field because of the significant price differences between them and common impurities in raw and processed textiles. Since animal fibers have remarkable similarities in their chemical and physical characteristics, specific identification methods have been studied and proposed following advances in analytical technologies. The identification methods of wool and fine animal fibers are reviewed in this paper, and the results of relevant studies are listed and summarized, starting from classical microscopy methods, which are still used today not only in small to medium enterprises but also in large industries, research studies and quality control laboratories. Particular attention has been paid to image analysis, Nir spectroscopy and proteomics, which constitute the most promising technologies of quality control in the manufacturing and trading of luxury textiles and can find application in forensic science and archeology.
... common solvents due to the presence of strong intra-and intermolecular disulfide bonds, hydrogen bonds, and van der Waals forces, making its dissolution and regeneration difficult [1][2][3]5,6]. Therefore, various approaches capable of cleaving the disulfide and hydrogen bonds, such as oxidation, reduction, acid-alkali, sulfitolysis methods, enzymatic hydrolysis, and the use of ionic liquids, have been explored to extract WK from wool wastes [1][2][3]6]. ...
... common solvents due to the presence of strong intra-and intermolecular disulfide bonds, hydrogen bonds, and van der Waals forces, making its dissolution and regeneration difficult [1][2][3]5,6]. Therefore, various approaches capable of cleaving the disulfide and hydrogen bonds, such as oxidation, reduction, acid-alkali, sulfitolysis methods, enzymatic hydrolysis, and the use of ionic liquids, have been explored to extract WK from wool wastes [1][2][3]6]. However, many of these methods have issues related to time consumption, high temperatures, rigorous reaction conditions, and some involve expensive, toxic, harmful, and poorly biodegradable compounds [2,3]. ...
... The most abundant was glutamic acid (19.65 mole %) followed by glycine (12.72 mole %) and leucine (9.42 mole %). The results obtained in our study agree with other research findings, which also observed that glutamic acid is the most abundant amino acid in keratin hydrolysates (Rajabinejad et al., 2018;Tsuda & Nomura, 2014). ...
... This is due to thermal decomposition of the wool hydrolysate. The results also show that the weight loss did not get to 100% even at 600 ºC thus indicating that the wool hydrolysate has good thermal stability as reported in the literature (Rajabinejad et al., 2018). It is evident that the curve is also not very steep, demonstrating the thermal stability of the wool hydrolysate. ...
Conventional dehairing methods in the traditional leather-making processes, consume large amounts of toxic chemicals and produce a toxic sludge/effluent, posing disposal challenges and consequently environmental pollution. The by-products of leather processing such as hair and fat, contain toxic chemicals. In this study, crude alkaline protease from bacillus cereus strain 1-p, was used to dehair sheepskin with up to 99.00% recovery of valuable wool and fat. The optimum temperature and pH for wool removal were found to be 30 <sup>°</sup>C and 11, respectively. The recovered wool was enzymatically hydrolyzed to obtain wool hydrolysate powder (48.1% yield). FTIR spectra of the wool hydrolysate showed the presence of amide A, I, and II absorption bands. Further, the amino acid analysis, revealed the presence of 15 amino acids, with glutamic acid (19.65 mole %), glycine (12.72 mole %), and leucine (9.42 mole %) being the most abundant. Fat was trans-esterified using methanol, in the presence of tert-butanol, and the resultant fatty acid methyl esters characterization was done using gas chromatography/mass spectrometry (GC/MS) analysis. GC/MS analysis showed the presence of 60 methyl esters corresponding to 60 fatty acids. The most abundant fatty acid was 9-octadecenoic (oleic) acid (41.64%), followed by hexa-decanoic (palmitic) acid (22.50%), and tetra-decanoic (myristic) acid (4.21%). Thermo-gravimetric analysis of the wool hydrolysate showed that it had good thermal stability. It is shown that crude alkaline protease extracted from bacillus cereus strain 1-p can completely eliminate the use of toxic sodium sulfide and lime in dehairing of skins/hide in tanneries, eliminating environmental pollution. Furthermore, the recovery of fat and wool using an eco-friendly enzymatic dehairing process can significantly reduce the pollution load in the effluent. The recovered wool and fats can be applied in the production of wool hydrolysate, which is high in protein content, amino acids and biodiesel.
... The treated fabrics were cured at 150°C for 5 min. The molecular mass of the extracted keratin and sericin was assessed by electrophoresis using a horizontal SDS-PAGE gel electrophoresis device (Cleaver Scienti c Ltd.) [27]. The amino acid composition of the extracted sericin was determined using the HPLC-Pico-Tag method, according to Millipore Cooperative (1987), in which the sample was hydrolyzed in 6 N HCl before analysis[28]. ...
A synergy of phytic acid (PA) and proteinic biopolymer, namely keratin and sericin, was adopted to boost the resistance to flame, ultraviolet rays, and electrostatic charges, as well as enhance hydrophilicity of acrylic fabric. An efficient flame retardant (FR) was synthesized by reacting calculated amounts of PA and pentaerythritol (PE) to form hexa-pentaerythritol phytate ester (HPP), which in turn reacted with a proteinic bioplymer in the presence or absence of a crosslinking agent to produce a multifunctional FR formulation. The prepared formulation was utilized as a multifunctional textile auxiliary for improving the resistance of alkali-hydrolyzed acrylic fabric to flame and UV rays and for enhancing its hydrophilic and anti-static properties. The solubility of the prepared formulation in different solvents at different temperatures was examined. The chemical structure of the synthesized functional FR was investigated using FTIR and by determining its phosphorus, nitrogen, and carboxylic contents. The mechanism of reaction between the synthesized FR and the hydrolyzed fabric was proposed. The discrepancy between the topography of the treated and untreated fabrics was monitored using scanning electron microscopy. The results revealed that the treated acrylic fabric exhibited a durable and superior resistance to flame, which was not adversely affected by washing up to 20 times. The anti-static property and wettability of the treated fabrics were highly improved, whereas their resistance to the deteriorative action of UV rays was enhanced to an almost adequate level. The proposed process is an additive method for improving some performance and comfort attributes of acrylic fabric without causing severe loss in the fabric’s strength.
... The outermost layer of skin epidermis, i.e., the stratum corneum, is covered by dead cells filled with densely packed keratin proteins. Keratins consist of hydrophobic (e.g., alanine and valine) and hydrogen-bond donor amino acids (e.g., glutamic acid and serine), 17 which can establish noncovalent π−π interactions and hydrogen bonding with phenolic compounds. 1 In addition, covalent attachment can occur through Michael addition reactions of oxidized phenol (quinones) with the thiol and amino side chains in amino acid residues, such as cysteine and lysine. ...
Bioadhesives are important for the future of medicine in their roles in wound closure and as measures to enhance wound healing. These adhesives are more effective and less invasive than conventional wound closure methods, such as surgical sutures or staples. Adhesive substances based on naturally occurring biological materials from living organisms harness phenolic compounds for their attachment to wet surfaces. For example, plants, such as Boston ivy, or animals, such as mussels, have evolved tissues that create optimal adhesion under a variety of challenging conditions, including in aqueous and saline environments. Current research aims at using biomimetic strategies to create a new generation of bioadhesives that will be better suited for medical use. Biomaterials design has evolved around integration of phenols with protein backbones among which gelatin has received particular attention due to its excellent bioactivity, biocompatibility, biodegradability, low cost, facile chemical tunability, and tissue-mimetic properties. Bioadhesion performance in these biomaterials is a strong function of polyphenolic functionality and the processing approach for their integration into hydrogel networks. A number of studies have used phenolic small molecules to modify biomacromolecules chemically for bioadhesion. One of the major hurdles in these studies is insufficient phenolic uptake due to low-yield modification chemistries and inherently limited functionalization capacity of proteins. Polyphenols are an attractive toolbox for bioadhesive design, as they not only enable stronger interactions with various substrates but also act as cross-linking points, strengthening polymer network cohesion. In addition, the cross-linking mechanism used for gelation of bioadhesives should be compatible with polyphenolic moieties, as, for instance, free-radical polymerization in the presence of phenolic compounds is compromised by their free-radical scavenging effects. Polyphenolic compounds derived synthetically from phenolic small molecules as well as those occurring naturally, such as tannins, have added a large library of additional functionality, such as antimicrobial and photothermal responsiveness, calling for further developments for applications in wound management.
In this Account, we review several recent breakthroughs in polyphenol-integrated gelatin that have been analyzed in the context of their use as bioadhesives. Polyphenols play important roles in covalent and noncovalent interactions with functional groups in biological substrates, including keratins, connective tissue, or soft internal tissues. We consider different polyphenol-carrying compounds for modification including catecholamines, phenolic amino acids, tannins, and lignins. We then discuss how these polyphenolic materials can be fabricated to mimic naturally derived bioadhesives through infusion, physical mixing, and copolymerization. We discuss the implications of using these bioadhesives, questioning their viability and prospects. Finally, we highlight current challenges and future opportunities for taking polyphenolic bioadhesives closer to clinical translation.
