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Morphology of melanosomes isolated from hair fiber using esperase. a, b SEM images of hair melanosomes; c, d TEM images of hair melanosomes; TEM images of e longitudinal and f transverse sections of melanosomes (V spherical vesicles, M membrane-like structure, SA sheet-like array structure in matrix, MT sheet-like structures in inner matrix)
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Hair contains about 80% keratins and 1–3% melanin packaged in melanosomes. Both of these are high-value and functional raw materials that have potential applications in wide-ranging fields. While keratin extraction has been widely refined, efficient methods of melanosome extraction are limited. The extraction of melanosomes requires complete remova...
Citations
... As such, the recycling, development, and application of keratin-containing waste provides an important means to address environmental pollution and energy shortages [7]. Keratin can easily be extracted from natural fur and hair, such as wool, chicken feathers, hog hairs, rabbit hairs, human hairs, and so on [8][9][10][11][12]. In this line, the development of keratin-based functional materials has become the key to solving waste fur and hair pollution. ...
The recycling, development, and application of keratin-containing waste (e.g., hair, wool, feather, and so on) provide an important means to address related environmental pollution and energy shortage issues. The extraction of keratin and the development of keratin-based functional materials are key to solving keratin-containing waste pollution. Keratin-based biofilms are gaining substantial interest due to their excellent characteristics, such as good biocompatibility, high biodegradability, appropriate adsorption, and rich renewable sources, among others. At present, keratin-based biofilms are a good option for various applications, and the development of keratin-based biofilms from keratin-containing waste is considered crucial for sustainable development. In this paper, in order to achieve clean production while maintaining the functional characteristics of natural keratin as much as possible, four important keratin extraction methods—thermal hydrolysis, ultrasonic technology, eco-friendly solvent system, and microbial decomposition—are described, and the characteristics of these four extraction methods are analysed. Next, methods for the preparation of keratin-based biofilms are introduced, including solvent casting, electrospinning, template self-assembly, freeze-drying, and soft lithography methods. Then, the functional properties and application prospects of keratin-based biofilms are discussed. Finally, future research directions related to keratin-based biofilms are proposed. Overall, it can be concluded that the high-value conversion of keratin-containing waste into regenerated keratin-based biofilms has great importance for sustainable development and is highly suggested due to their great potential for use in biomedical materials, optoelectronic devices, and metal ion detection applications. It is hoped that this paper can provide some basic information for the development and application of keratin-based biofilms.
... The keratin films showed porous and sheet-like cross-sectional structures with dispersed granular particles, while the top surface was smooth with no visible pore observed. Some spherical groves were found on the film surface which might be the granular particles observed in the crosssectional images (Fig. 2c & d), which are the melanosomes in hair [24]. Interestingly, distinct and significant structures were observed across the surface and cross-sectional images. ...
An easy-to-handle keratin film was successfully fabricated using solely purified hair keratins. Keratin was extracted from human hair by an existing protocol. The extracted keratin was made into a mechanically stable film by solution casting and air-drying at room temperature. The films obtained were characterized for surface morphology, wettability, protein secondary structures, mechanical properties, permeability, and thermal properties. Interestingly, the keratin film showed distinct surface and cross-sectional morphology, and protein secondary structure transformation. In addition, the keratin film exhibited Young’s modulus of 1.05 ± 0.09 GPa when it was dry. In the wet state, the keratin film behaved as viscoelastic material and was highly stretchable at 179 ± 17% strain at break. Permeability test was conducted using 20 kDa-FITC dextran which revealed an anomalous diffusion mechanism through the keratin film. Additionally, the keratin film elicited positive cellular responses by human epidermal keratinocytes (HEKs) in terms of enhanced cell proliferation, viability, keratin 14 expression, and IL-1α secretion, in comparison to collagen I. Taken together, a human hair keratin-based film with its mechanical and thermal stability, and cytocompatibility, presents a promising platform for cell culture applications.
Sustainable agriculture can be achieved by upcycling and repurposing
organic wastes for high-value applications. Keratin and cellulose are two natural
biopolymers which are plentiful in biowastes such as hair, poultry feathers, wood shavings,
and vegetable trimmings. In this study, these waste-derived biopolymers are converted into
bioactive nutrient substrates that can support crop development in hydroponic culture
systems. Keratin extracted from human hair (HHK) and cellulose nanofibers (CNFs)
obtained from wood pulp were fabricated into composite substrates by freeze-drying. The
substrates exhibited highly microporous structures, superior hydrophilicity, and excellent
mechanical resilience. The obtained substrates not only serve as a physical carrier to
support seed germination and seedling development but also function as advanced nutrient
delivery platforms by the incorporation and controlled release of micronutrient-doped
carbon dots, in addition to keratin degradation. Functional experiments using the model
plant Arabidopsis and crops including Bok Choy (Brassica rapa) and Arugula (Eruca
vesicaria) indicated that these substrates have the potential to be customized for enhanced seedling development in comparison to
conventional substrates. This study demonstrates the feasibility and potential of upcycling and repurposing keratinous and cellulosic
wastes to provide a sustainable solution for targeted nutrient delivery to crops.
Human hair is a potential biomaterial for biomedical applications. Improper disposal of human hair may pose various adverse effects on the environment and human health. Therefore, proper management of human hair waste is pivotal. Human hair fibre and its derivatives offer various advantages as biomaterials such as biocompatibility, biodegradability, low toxicity, radical scavenging, electroconductivity, and intrinsic biological activity. Therefore, the favourable characteristics of human hair have rendered its usage in tissue engineering (TE) applications including skin, cardiac, nerve, bone, ocular, and periodontal. Moreover, the strategies by utilising human hair as a biomaterial for TE applications may reduce the accumulation of human hair. Thus, it also improves human hair waste management while promoting natural, environmentally friendly and non-toxic materials. Further, promoting sustainable materials production will benefit human health and well-being. Hence, this paper reviews and discusses human hair characteristics as sustainable biomaterials and their recent application in TE applications.
