Keratin Films Research Articles

Effect of precipitation methods on physicochemical properties of keratin films produced from chicken feather waste

Effect of precipitation methods on physicochemical properties of keratin films produced from chicken feather waste

Production and characterization of human hair keratin bioplastic films with novel plasticizers

Since their invention, conventional plastics have contributed in the betterment of the society in numerous ways, nevertheless their deleterious impacts on the natural ecosystems and living creatures is irrefutable. The management of plastic waste generated is a concern worldwide and therefore quest for the plastic alternates or bioplastics is imminent. Here, we explore the suitability of keratin from human hair waste as the candidate for the production of bioplastic films. Keratin extracted from hair was used to form the films or ‘kertics’ by solution casting and curing. Ethanediol, di-ethylene glycol and tri-ethylene glycol were used as novel plasticizers along with glycerol in the keratin film formation. The film prepared were of the thickness 190–220 µm with the area of about 4.54 ± 0.2 cm2. Water uptake by G100, ED100, DEG100 and TEG100 films was recorded to be 4.8, 6.2, 4.9 and 6.3% respectively. FESEM analysis revealed that the films with 100 µl of 1% glycerol (G100) had continuous surface morphology except few pits of 0.1 µm, also DEG100 and TEG100 films have the most uniform surface morphology with no evident pits, holes or bulges. X-ray diffractogram showed characteristic peak of keratin at 19.5° and the d-spacing value observed was 0.45 nm. The FTIR studies suggested that the films retained keratin in non degraded form, and possessed the characteristic Amide peaks. The films were also found to be biodegradable in studies involving keratinophilic fungal strain of A. oryzae. These films could found potential applications in packaging industry, disposable items manufacturing and biomaterial generation.

Densely crosslinked protein bioplastics with superior stretchability and desirable wet stability via quality protein restoration

We have demonstrated that dithiol-based crosslinkers are most suitable for protein materials with high contents of cysteine. Crosslinking is always the effective approach to improvement in properties of protein materials. However, most crosslinking technologies damage structures of protein materials due to harsh crosslinking conditions, or form uncontrollable and unstable crosslinkages. In this work, we selected dithiols with different chain lengths and flexibility to form disulfide crosslinkages via reduction and oxidation at room temperature. Sustainable dithiols were screened by computational simulation for bioplastic uses. Since the reactions were performed at room temperature, keratin backbone structures were intact. Our developed model indicates that number of sigma bonds in crosslinkages and retention of crosslinking, dominated by sigma bonds in crosslinkages, quantitatively controlled mechanical properties of regenerated keratin films. Wet-stable keratin films with excellent stretchability were developed without any plasticizers and secondary polymers. Some properties of our bioplastics via quality restoration were similar to some petroleum-based products. For example, feather-derived bioplastics had dry stress, wet stress, dry breaking elongation, and wet elongation of 35 MPa, 10.2 MPa, 70%, and 105%, respectively. After seven days in water, the stress retention of films was as high as 85%. This work promoted the application of keratin bioplastics in food, pharmaceutical and cosmetic industries.

Production and characterisation of mucilage-based keratin films using goose feathers

Production and characterisation of mucilage-based keratin films using goose feathers

Edible pullulan enhanced water-soluble keratin with improved sizing performance for sustainable textile industry

Feather keratin from waste feather has become an attractive target to replace petroleum-based Poly (vinyl alcohol) sizes due to its easy film-forming ability, excellent adhesive property, biodegradability and low cost. However, poor water-solubility and brittleness of pure keratin films have become the bottlenecks and restricted the application of keratin as sizing agents. Therefore, water-soluble keratin was extracted by the reduction-preservation method and enhanced by saccharides in aqueous system to obtain all-green keratin-based slurry. The results showed that the keratin-based slurry exhibited improved sizing performance in the order of sucrose ≤ glucose ≤ pullulan by the moderate Maillard reaction. Among them, the fabricated pullulan-keratin sizes films had 27.86 %, 2684.08 % and 2911.31 % increment in tensile strength, elongation and work of facture compared with pure keratin sizes films. Besides, the addition of pullulan and subsequently moderate Maillard reaction improved the thermo-tenacity of keratin-based sizes, which was expected to tackle with the brittleness of pure keratin size films. In addition, novel pullulan-keratin sizes had good sizing performance and high desizing efficiency to cotton, cotton/polyester and polyester yarns and fabrics. Successful utilization of pullulan-keratin sizes will bring opportunities for high value utilization of waste feather and promote the green and low-carbon development of textile industry.

Keratin films for ocular surface reconstruction: Wound healing in an in-vivo model

The most commonly used tissue substitute for ocular surface reconstruction is human amniotic membrane (AM). Because of its low biomechanical strength and intransparency there is a need to search for alternatives of consistent quality. This study, further explored the biocompatibility of Keratin Film (KF) and its ability to sustain corneal epithelial wound healing.In three equal groups of 5 New Zeeland white rabbits a 4 mm superficial keratectomy was created in the right eye. Five eyes received a KF, five a human AM graft and the remaining five no implant. All eyes were treated with ofloxacin and dexamethasone eye drops and followed up for 10 days. Corneal fluorescein staining, vascularization, and transparency were assessed using slit lamp biomicroscopy according to a standardized grading score during and at the end of follow-up. The corneal-scleral-button was excised and processed for histology.After 10 days all eyes which had received a KF showed complete epithelial healing and no signs of neovascularization. In the AM group 1 eye showed a persistent epithelial defect at day 10 and 2 eyes showed neovascularization at day 7 resolving at day 10. Transparency improved progressively both in the KF group as well as in the AM group towards the end of the follow. Histology showed a multilayer epithelium firmly adherent to the KF with no evidence of keratocyte migration or inflammatory reaction in the corneal stroma.In this study on rabbit eyes KF better supported corneal epithelial wound healing than amniotic membrane.

Nitric oxide releasing poly(vinyl alcohol)/S-nitrosated keratin film as a potential vascular graft.

Nitric oxide (NO) releasing vascular graft is promising due to its merits of thromboembolism reduction and endothelialization promotion. In this study, keratin-based NO donor of S-nitrosated keratin (KSNO) was blended with poly(vinyl alcohol) (PVA) and further crosslinked with sodium trimetaphosphate (STMP) to afford PVA/KSNO biocomposite films. These films could release NO sustainably for up to 10 days, resulting in the promotion of HUVECs growth and the inhibition of HUASMCs growth. In addition, these films displayed good blood compatibility and antibacterial activity. Taken together, these films have potential applications in vascular grafts.

Bacterial nanocellulose patches as a carrier for hydrating formulations to improve the topical treatment of nail diseases

Bacterial nanocellulose has been widely investigated for wound healing applications, mainly due to its moisturizing capabilities and biocompatibility. Even though the topical therapy of nail diseases could benefit from these properties, this application has not yet been investigated. Therefore, actively hydrating nail patches based on bacterial nanocellulose were developed to improve the delivery of ciclopirox olamine and Boswellia serrata extract through the nail plate. The nanocellulose matrix was used to enable the application of hydration enhancing solutions based on glycerol and urea as a mechanically stable patch. While the favorable mechanical characteristics of the material remained unchanged, an increase of the incorporated glycerol concentration enhanced the transparency and wetting capacity of the patches. A biphasic drug release from the patches could be observed for drug and extract with a faster release for the hydrophilic ciclopirox olamine. High glycerol concentrations correlated with increased cumulative release and permeation through keratin films for drug and extract, demonstrating the hydration driven permeation enhancement. Patches containing ciclopirox olamine showed strong antimycotic effects against relevant pathogens for onychomycosis. The present finding proposed the combination of bacterial nanocellulose with glycerol, urea and different drug as a promising platform for the local treatment of nail diseases.

Fabrication of mechanical robust keratin composites via mussel-inspired surface modification of cellulose nanocrystals

In this study, a novel bio-marine mussel inspired surface modification of cellulose nanocrystal and its enhanced interfacial strength toward keratin composites was developed and demonstrated for the purpose of developing high performance and fully renewable keratin composites. XPS and FTIR study of the poly-dopamine modified cellulose nanocrystal (PDA@CNC) confirmed that the functional layer was successfully coated on cellulose nanocrystal surface. The mechanical strength of 3% PDA@CNC/keratin composites could reach as high as 29.01 MPa, compare with that of 9.17 MPa of pure keratin film, due to the enhanced interfacial adhesion between PDA@CNC and keratin. This study demonstrated a facial and effective strategy for manufacturing mechanical enhanced keratin functional materials.

Dexamethasone-loaded keratin films for ocular surface reconstruction

Amniotic membrane (AM) is often applied as a substitute material during ocular surface reconstruction. However, since AM has several disadvantages, alternative materials must be considered for this application. Keratin films made from human hair (KFs) have previously been presented as a promising option; they exhibited suitable characteristics and satisfactory biocompatibility in an in vivo rabbit model. Nevertheless, dexamethasone (DEX) eye drops are necessary after surgery to suppress inflammation. Since eye drops must be administered frequently, this might result in poor patient compliance, and the release of DEX at the transplant site would be clinically beneficial. Therefore, we aimed to incorporate DEX into KFs without hindering the positive film characteristics. Drug-loaded KFs were generated either by suspension technique or by the addition of solubilizing agents. The resulting specimens were analyzed regarding appearance, loading capacity, transparency, mechanical characteristics, swelling behavior and in vitro release. Furthermore, biocompatibility was assessed in vitro by determining the cell viability, seeding efficiency and growth behavior of corneal epithelial cells. The amount of incorporated DEX influenced the transparency and biomechanical properties of the films, but even highly loaded films showed properties similar to those of AM. The suspension technique was identified as the best incorporation approach regarding chemical stability and prolonged DEX release. Moreover, suspended DEX in the films did not negatively impact cell seeding efficiencies, and the cell-growth behaviors on the specimens with moderate DEX loads were satisfactory. This suggest that these films could comprise a suitable alternative material with additional anti-inflammatory activity for ocular surface reconstruction.Graphical

Extraction of keratin from wool and its use as biopolymer in film formation and in electrospinning for composite material processing

Keratin is one of the most important protein materials and can act as a sustainable biopolymer for manifold applications. This paper reports on a sustainable extraction method for keratin from wool fiber materials. The use of this extracted keratin for polymer film preparation and preparation of nano-composite materials by electrospinning is investigated. The preparation of keratin films is done in combination with the both biopolymers alginate and pectin. Keratin nanofibers are prepared in combination with the polymer polyacrylonitrile PAN. A view on antibacterial properties of the prepared films is given. As further analytic methods, Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetry, and scanning electron microscopy (SEM) are used. Finally, the preparation of new keratin containing materials is described, which may be used in future for biomedical applications.

Development of a mechanically stable human hair keratin film for cell culture

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.

Characteristics of regenerated keratin and keratin-based film

Characteristics of regenerated keratin and keratin-based film

A Nano-Silver Loaded PVA/Keratin Hydrogel With Strong Mechanical Properties Provides Excellent Antibacterial Effect for Delayed Sternal Closure.

Delayed chest closure (DSC) is widely performed during the treatment of congenital heart diseases. However, the high prevalence of surgical site infection (SSI) in patients undergoing DSC affects prognosis negatively. Herein, we designed a suturable poly (vinyl alcohol)/keratin film loaded with silver nanoparticles (AgNPs) as an alternative material for DSC, which was named PVA/Keratin/AgNPs. The PVA/Keratin/AgNPs films exhibited significantly enhanced mechanical strength after crosslinking by sodium trimetaphosphate (STMP). These films were non-toxic, and cells proliferated with good morphology after 1 week of culture. In addition, PVA/Keratin/AgNPs films provided superior antibacterial ability, as evidenced by the eradication and lower growth rate of Staphylococcus aureus and Escherichia coli. Finally, the PVA/Keratin/AgNPs films were demonstrated to successfully cover the chest cavity temporarily and protect the chest cavity from bacterial infection. These results indicated that the PVA/Keratin/AgNPs films have great prospects to be further exploited for clinical applications in DSC.

Mechanical Properties of Keratin Composite Films Using Poultry Feathers as Reinforcement Fibers

In this work, the chemical and low temperature nitrogen plasma methods were adopted to treat the raw material, untreated poultry feather (UPF), to obtain thechemically treated poultry feather (CPF), plasma treated poultry feather (PPF) and chemically & plasma treated poultry feather (CPPF), respectively. Then the four kinds of feather fibers were used as reinforcement fibers to prepare feather/keratin composite films with the ratio from 1% to 12% (relative to the mass of keratin in the film), respectively. The effect of feather treatment method and the feather fiber content onthe mechanical properties of films were studied. The results show that UPF has poor enhancement performance in keratin films, and CPF and PPF have better reinforcing effect than UPF. The keratin films reinforced by CPPF have relatively strong breaking strength, indicating that the CPPF plays an active reinforcing role in the composite film and has the most potential as a reinforcement fiber. For all the samples, when the fiber content is around 7%, the composite film has the best mechanical properties.

Ductile keratin films from deep eutectic solvent-fractionated feathers.

Feathers, an industrial by-product, are a valuable source of keratin that could be used, for example, in the preparation of films for biomedical and packaging applications. However, the utilisation of feather keratin requires scalable processes to convert feathers into a feasible keratin stream. This paper shows how deep eutectic solvent (DES) fractionated feathers could be converted into strong films. In the DES fractionation process, two keratin fractions with different molecular weights were obtained. The films made of the high molecular weight keratin fraction had better mechanical properties and stability against moisture than the films made of the low molecular weight keratin fraction. The strength properties were further improved by cross-linking the keratin with diglycidyl ether enabling the formation of a uniform keratin network, whereas glutaraldehyde did not show a clear cross-linking effect. These keratin films could be used, for example, in food packaging or medical applications such as wound care.

Obtaining human hair keratin-based films and their characteristics

Background. Keratins are natural biopolymers with a wide range of applications in the field of biotechnology. Materials and Methods. Extraction of keratins was performed by a modified Nakamura method using 250 mM DTT. The protein concentration in the supernatant was determined by Bradford method. The protein composition was studied by their electro­phoretic separation in a polyacrylamide gel in the presence of sodium dodecyl sulfate. The films were made by casting. The surface characteristics of the films were determined using a scanning electron microscope REMMA-102. The elemental composition of the films was determined using an X-ray microanalyzer. Results. The protein concentration in the supernatant was 3.75 mg/mL. After using dithiothreitol in the extraction mixture, we obtained proteins of intermediate filaments with a molecular weight of 40–60 kDa and a low Sulfur content. In the low molecular weight region, we obtained keratin-associated proteins with a molecular weight of 10–30 kDa and a high content of Sulfur. These proteins belong to fibrillar proteins, which can be used as a matrix for the creation of new keratin-containing biocomposites with a wide range of applications in reparative medicine and tissue engineering. Based on the obtained keratin extract, polymer films with and without the addition of glycerol were made. Scanning electron microscopy revealed that glycerol provided the film structure with homogeneity and plasticity due to the accumulation of moisture after the fixation by water vapor. The X-ray microanalysis of films revealed such elements as Sodium, Silicon, Sulfur, Potassium. Among the detected elements, Sulfur has the largest share that is due to the large number of disulfide bonds in the keratin molecule. Conclusions. The polymer keratin films with the addition of glycerol demonstrated better mechanical properties and can be used in biomedicine.

Improvement of Flexibility of Keratin Film by Zinc Acetate

This work aimed to improve the flexibility of keratin film by blending with zinc acetate. Films were prepared by casting methods before the characterization of their morphology, structure, and crystallinity. The keratin film with zinc acetate had a rougher texture than the native keratin film and changed absorption peaks appeared in the FTIR spectrum. Blending with zinc acetate (Zn(Ac)2) helped to reduce the β-sheet structure as well as the crystallinity of the keratin film. This result clarified that Zn(Ac)2 could improve the flexibility and properties of the brittle and fragile films.

Fabrication of mechanical robust keratin film by mesoscopic molecular network reconstruction and its performance for dye removal

Regenerated keratin-based adsorbents have attracted much attention in environmental pollution remediation. However, fabricating keratin-based adsorbents with excellent adsorption performance is still a challenging issue due to its weak mechanical property. In this study, mechanical robust keratin composite films were designed and engineered at mesoscopic scale by molecular network reconstruction strategy. It was found that the β-crystallites structure of silk fibroin template could induce the transformation of free unfolded molecular chains of keratin to β-sheet conformation and further resulted in the controllable manipulating of the mechanical properties of keratin films. This mechanical reinforced composite film showed high adsorption efficiency and capacity for dyes as well as ideal regeneration and recycling performance. Adsorption behavior of reactive brilliant blue KN-R by keratin composite films was comprehensively studied. The adsorption capacity (qe) and removal efficiency for KN-R by the adsorbent could reach as high as 190.84 mg/g and 98.52%, respectively. The adsorbent exhibited excellent regeneration and recycling performance due to its mechanical robustness. The molecular network reconstruction strategy is both straightforward and effective for fabricating mechanical robust adsorbent for pollutant remediation.

Antifungal efficacy of liquid poloxamer 407-based emulsions loaded with sertaconazole nitrate.

Drug delivery into the human nail plate for the treatment of onychomycosis is difficult due to limited permeability of the nail plate. Semisolid poloxamer 407-based formulations have recently shown promising results for drug delivery into and through the nail plate. In this study, liquid poloxamer 407-based emulsions loaded with sertaconazole nitrate have been developed and the permeation behavior was determined in vitro using modified Franz diffusion cells. The antifungal efficacy was evaluated in an infected nail plate model, where the growth inhibition of Trichophyton rubrum was observed. Bovine hoof plates and keratin films made from human hair were used as models for the human nail plate. In both cases, formulations with low viscosity and high water content showed best results despite a lower solubility of sertaconazole nitrate, suggesting that the composition of the vehicle plays a major role in permeation through the membrane. In addition, an API content close to saturation solubility had a positive effect on permeation.