Keratin is widely recognized as a high-quality renewable protein resource for biomedical applications. A large amount of rabbit hair waste is produced in textile industries, because it has high medullary layer content, but poor spinnability. Therefore, it is of great significance to extract keratin from waste rabbit hair for recycling. In this research, an ultrasonic-assisted reducing agent-based extraction method was developed and applied to extract keratin from rabbit hair. The results showed that the ultrasonic treatment had a certain destructive effect on the structure of the fiber, and when combined with reducing agent, it could effectively promote the dissolution of rabbit hair, and extract keratin with high molecular weight between 31 and 94 kDa. The structure and properties of keratin were studied. Compared to the rabbit hair, the cystine content of keratin was significantly reduced, and the secondary structure changed from α-helix to β-sheet. The keratin products show excellent biocompatibility and antioxidant capacity. In addition, large keratin particles can be formed by assembly with a balance between intermolecular hydrophobic attraction as the concentration of urea in keratin solution decreased during dialysis.
Keratins are highly attractive natural biomaterials for medical applications due to their inherent self-assembly characteristics and biocompatibility. In this study, the molecular mechanism of rabbit hair keratin (RHK) gelation during cryogelation is investigated and the influence of cryogelation parameters on the gelation of keratin is systematically evaluated. Re-xidation of free cysteine thiols and formation of hydrogen bond are determined to be the main stabilizing forces in self-assembly of RHK gel, and ionic bonds are found to affect the uniformity of keratin hydrogels. pH affects the gelation by changing the electrostatic interaction between keratin molecules. Keratin will accumulate when pH is too low, but the stability of keratin hydrogels becomes worse when the pH is too high. With successive freezing-thawing (FT) cycles, the storage modulus of RHK cryogels substantially improved from 240.66 Pa at FT cycle 3 to 2483.3 Pa at FT cycle 9. Maintaining the balance of the interactive force between keratin molecules and between keratin molecules and water molecules is the basis of preparing uniform and stable keratin hydrogels.
Keratins are highly attractive for medical applications due to their inherent self-assemblies characteristics and biocompatibility. However, nearly all researches have focused on the properties of hybrid hydrogels which was prepared from human hair keratin with other materials, and the preparation methods and properties of pure keratin hydrogels are rarely studied. Thus, we extracted keratins from rabbit hair, and a low concentration and high purity RHK hydrogel was then prepared by a simple freeze–thaw cycle and used to study gelation and the optical properties. The results indicated that RHK keratin hydrogel is a reversible thixotropic system and elastic modulus the storage modulus (G′) substantially improves with freeze–thaw cycles. The systematic assessments including microstructural observation, porosity, and the secondary structure confirmed that the structure and properties of keratin hydrogels can be changed by controlling freeze–thaw cycles. Meanwhile, it is found that RHK hydrogel had high optical transmittance, and still maintained its fluorescent properties, which would be useful to observe the wound healing and locate the drug delivery process.
Ce-doped TiO2 nanotubes (Ce-TNTs) were synthesized by a hydrothermal method to obtain high-efficiency adsorption and photodegradation abilities for methylene blue (MB) dye. The transmission electron microscope (TEM), X-ray diffractimeter (XRD), nitrogen adsorption, X-ray photoelectron spectrum (XPS), and photodegradation tests were used to characterize the morphology, microstructure, ionic valance, and degradation behaviors of the TNTs. Results show that the Ce-doped TNTs are composed of anatase tubulars with an inner-hole diameter of 5 nm, outer diameter of 10–15 nm, length of several hundred nanometers, and a small amount of CeO2 nanoparticles. Ce3+ and Ce4+are dissolved in the anatase crystals, the ratio of which increases with an increase in Ce addition. Ce-doping yields a higher amount of surface oxygen, which results in a strong physical and chemical adsorption to the cationoid MB. 2.5 mol% Ce-doping produces the largest specific surface area, porosity, and photoabsorption threshold and the lowest Zeta potential, yielding the highest adsorption efficiency and photocatalytic ability even under sunlight irradiation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.