Table 4.
Keratin films developed from different animal by-product sources.
| Source | Extraction Method | Aims | Plasticizers | Method for Film Production |
Results | Reference |
|---|---|---|---|---|---|---|
| Chicken feathers | Alkaline hydrolysis | Producing bioplastic from keratin and microcrystalline cellulose | Glycerol | Solvent casting | Keratin was extracted from chicken feathers using sodium sulfide and used for producing biodegradable films. Prepared films showed a TS of 3.62 MPa, YM of 1.52 MPa, and EAB of 15.8% that makes it suitable for producing bioplastic films | [141] |
| Sheep Wool Keratin | Alkaline mild oxidative method | Cross-linking of sheep wool keratin with sodium dodecyl sulphonic acid (SDS) | Glycerol | Solvent casting | Prepared films showed considerable transparency, UV-barrier properties, and thermal stability up to 200 °C. Using SDS leads to more hydrophobic material but with less plasticizing effects. Cross-linking of films with formaldehyde leads to high mechanical strength. Biodegradability assay showed 40% of degradation for films after 5 days of composting. | [137] |
| Chicken feather | Hydrolase feather using urea, Na2S.9H2Oand SDS | Developing keratin films loaded with dialdehyde carboxymethyl cellulose (DCMC) | Glycerol | Solvent casting | Covalent and hydrogen bonds occurred between keratin and DCMC. Cross-linked films showed good UV-barrier properties and transparency. However, DCMC decreased the TS and moisture sensitivity of the films compared to the control keratin films. | [138] |
| Chicken feather | Acylation process | Producing thermoplastic films by acylation of keratin | Glycerol | compression-molding | Acylation process leads to develop thermoplastic keratin as a green and inexpensive product. Acylated keratin showed the melting peak around 115 °C which was slightly higher than weight loss and thermal degradation. Produced films were transparent and biodegradable. | [142] |
| Chicken feather | Sulphitolysis method | Studying the effect of processing condition and blending keratin on the films | PLA nanofibers | electrospinning | The extracted keratin exhibited a non-Newtonian behavior that could not form nanofiber via electrospinning. Therefore, by blending with PLA (10% wt), the keratin-based material could be prepared. PLA decreased the glass transition temperature of keratin. | [143] |
| Bovine hair | Immunization via sodium hydroxide | Using hair wastes as keratin source for films production | Glycerol, lactic acid | Thermo-compression | Films prepared by thermos-compression (147 kN, 120 °C or 160 °C, and 4 min). The films were opaque/dark and higher processing temperature or lactic acid led into a higher solubility in water. By increasing the amount of plasticizers, the amount of TS, YM, and EAB of the films decreased while the strain at break increased. | [144] |
| Chicken feather | Extract by peracetic acid Solution followed by centrifuge |
Producing keratin films by electrospinning and citric acid vapor modification | electrospinning and citric acid (CA) vapor modification |
CA vapor cross-linking increased the nanofibers diameter compared to water vapor. CA significantly improved the thermal stability and water resistance of keratin nanofibers. TS and EAB for CA cross-linked keratin improved 1.2 and 2 times compared to untreated nanofibers. CA vapor treatment increased the hydrophobicity of nanofibers. | [139] | |
| Duck feathers | Solution containing urea, SDS, and sodium bisulfite |
Study the plasticizing effect of 1,8-Octanediol in keratin films | 1,8-Octanediol (OD) | Solvent casting | Two types of keratin were extracted (reduced and native keratin). The presence of OD increased the hardness of films. Cross-linking with formaldehyde improved the mechanical properties and water resistance of the films. | [140] |
| Chicken feathers | Alkaline agent (NaOH) | Improve properties of keratin films by using microcrystalline cellulose | PVA/glycerol | Solvent casting | Addition of microcrystalline cellulose (2%) increased the hydrogen bonds between keratin protein and cellulose. MC improved the surface morphology and increased the crystallinity and thermal properties of keratin film. | [145] |
| White chicken feathers | NaOH solution followed by centrifuge | Manufacturing blended keratin films incorporated with essential oils | Sorbitol | Solvent casting | Addition of gelatin significantly increased the TS and EAB of keratin films. Further addition of cinnamaldehyde improved the mechanical properties of composite films. Composite films loaded with clove oil used for packaging smoked salmons and the results showed that it decreased the population of pathogenic microorganisms during storage of salmon and it also reduced the peroxide value and thiobarbituric acid compared to control samples. | [146] |
| Chicken feathers | NaOH solution followed by centrifuge | Study the effect of nanoclays and plasticizers on keratin films | Glycerol: Sorbitol | Solvent casting | The use of 1:3 or 0:1 (w/w) blend of glycerol and sorbitol showed the best mechanical properties for the films. However, the incorporation of nanoclay improved the physical properties of keratin films by increasing TS and decreasing WVP compared to pure keratin films. Films incorporated with 3% of nanoclay showed the most suitable mechanical and barrier properties. | [147] |
| Chicken feathers of Gallus gallus domesticus | Sodium bisulfite, urea, and SDS solution | Developing keratin-alginate fibers for industrial biodegradable materials | Glycerol | Solvent casting | Dual cross linked keratin-alginate fibers were successfully produced. N-(3-Dimethylaminopropyl)-N0-ethylcarbodiimide hydrochloride and calcium ions were the first and second cross-linking agents, respectively. Cross-linking significantly improved the strength, modulus, and toughness by 27, 20, and 33%, respectively. Cross linking improved the gravimetric toughness of the fibers and the authors suggested that for textile or tissue engineering applications. | [148] |
| Goat hoof | Soxhlet apparatus | Biopolymer film fabrication from keratin, fibrin, and gelatin | 2% (w/w) glycerol and 3% (w/w) tetrathylorthosilicate | Solvent casting | Wound-healing films from keratin, blood fibrin, gelatin, along with mupirocin were successfully prepared. The study showed biompactibility, cell viability, cell adhesion, and proliferation of blended polymers which can be used as a cheap and biodegradable film for supporting wound healing. | [149] |
| Chicken feather | Sodium bisulfite, urea, and SDS solution | Manufacturing keratin films cross-linked by dialdehyde starch (DAS) | Glycerol | Casting method | Cross-linking increased the compactness, amorphous structure, and transparency of keratin films. Cross-linked films showed lower solubility and the films with 2% DAS had a higher EAB and WVP compared to control films while the TS decreased. | [150] |
| Chicken feather | Alkali extraction and acid precipitation by urea and sodium sulfide | Developing bioplastics from hydrolyzed keratin films | Glycerol | Hot-pressing process | The results showed that high temperature and pressure improved the compatibility between glycerol and hydrolyzed keratin molecules. By increasing the glycerol content in films, the TS decreased while the solubility and EAB increased. Prepared films exhibited a low amount of solubility in water and addition of higher amount of glycerol increased WVP of films. | [151] |
| Quail feathers | Alkali extraction by NaOH and sodium sulfide | Manufacturing antibacterial keratin scaffolds incorporated with silver nanoparticles | - | Blending with PVA as a host polymer | Scaffolds with 0.75 wt% of keratin produced more uniform structure with less beads formation and exhibited a high antibacterial activity against Gram-positive (99.9%) and Gram-negative (98%) bacteria. Presence of keratin and silver nanoparticles, reduced the cytotoxicity and enhanced the viability of scaffolds. | [152] |
| Chicken feathers | Using urea, SDS, 2-mercaptoethanol, and tris(hydroxymethyl)-aminomethane solution | Study the effect of polyethylene glycol molecular weight on physical properties of films | Polyethylene glycol with different molecular weights (400, 1500, 4000, 6000) | Solvent casting | By increase in PEG molecular weight, the equilibrium moisture of keratin films reduced. PEG 400 was the best plasticizer in term of lower water solubility and WVP and also reduced the brittleness of the films. | [153] |