Figure 2 - available via license: CC BY
Content may be subject to copyright.
SEM images of fibrous membranes with different concentrations of polymer mats: (a) Ker.0%/PA6, (b) Ker.30%/PA6′, (c) Ker.30%/PA6, (d) Ag.1%-Ker.30%/PA6, (e) Ag.10%-Ker.30/PA6, (f) Ker.50%/PA6, and g) Ker.70%/PA6. The histograms show the distribution of fiber diameters corresponding to their SEM image. (h) TEM images, (i) HAADF-STEM (high-angle annular dark field-scanning transmission electron microscopy), and the corresponding EDS (energy dispersive spectrometer) mapping of the Ag, S, and N elements in composite nanofibers.
Source publication
Coarse wool is a kind of goat wool that is difficult to further process in the textile industry due to its large diameter, dispersion, better strength, and less bending. Therefore, coarse wool is often discarded as waste or made into low-cost products. In this work, keratin was extracted from coarse wool by a high-efficiency method, and then, an Ag...
Contexts in source publication
Context 1
... electrophoresis analysis was performed to identify keratin with the two samples (M1 and M2; Figure S2). Both specimens showed high intensity bands below 21 kDa, but the latter, M2, had different bands at around 31 to 97.4 kDa. ...
Context 2
... morphology of Ag-Keratin/PA6 composite membranes with different keratin contents from 0% to 70% are shown in Figure 2. It indicates that all samples have a uniform structure with a random orientation and wide, large fiber diameters. ...
Context 3
... addition, the diameters of Ker.30%/PA6 decrease from 192 nm to 168 nm with the addition of AgNPs, which could be explained by the conductivity of the solution (Table 1). HAADF-STEM and the corresponding EDS (energy dispersive spectrometer) mapping (Figure 2i) show that the Ag and S (only in keratin) elements are uniformly distributed in the electrospun nanofibers. ...
Citations
... The membrane obtained by combining keratin and polyamide 6 may be doped with silver, Ag, resulting in a good absorbent which can be used in air purification [269]. ...
The environmental invasion of plastic waste leads to, among other things, a reassessment of natural fibers. Environmental pollution has shown the importance of the degradability, among other properties, of the raw materials used by the textile industry or other industrial fields. Wool seems to be a better raw material than the polymers that generate large quantities of micro-and nano-plastics, polluting the soil, water, and air. However, the usual processing of raw wool involves a number of chemically very polluting treatments. Thus, sustainable procedures for making wool processing environmentally friendly have been considered, leading to the reappraisal of wool as a suitable raw material. Besides their applications for textile products (including smart textiles), new directions for the valorization of this natural material have been developed. According to the recent literature, wool may be successfully used as a thermal and phonic insulator, fertilizer, or component for industrial devices, or in medical applications, etc. In addition, the wool protein α-keratin may be extracted and used for new biomaterials with many practical applications in various fields. This review makes a survey of the recent data in the literature concerning wool production, processing , and applications, emphasizing the environmental aspects and pointing to solutions generating sustainable development.
... TMP, AgNP, and P6-TMP-AgNP membranes were characterized in the Interdisciplinary Laboratory of Electrochemistry and Ceramics at the Department of Chemistry of the Federal University of São Carlos (UFSCar). The different concentrations of the membranes obtained were characterized by the technique of energy-dispersive X-ray spectroscopy (EDX) [53], absorption spectroscopy in the mid-infrared region (FTIR) [54], scanning electron microscopy (SEM) [17], solid-state nuclear magnetic resonance (ss-NMR) [55], thermogravimetric analysis (TGA) [56], differential scanning calorimetry (DSC) [57] and thermodynamic and mechanical analysis (DMTA) [58], UV-Vis absorption spectrophotometry [59], X-ray Diffraction (DRX) and Energy Conversion Solutions (XPS) [60], Transmission Electron Microscopy (TEM), and dynamic light-scattering (DLS) [61]. The data for elasticity modulus, elongation at break, and tensile strength were normally distributed and were subjected to one-way ANOVA, followed by the Student-Newman-Keuls post hoc test (p < 0.05; SigmaPlot 12.0 software, Systat Software Inc., San Jose, CA, USA). ...
This study aimed to develop a polymeric matrix of polyamide-6 (P6) impregnated with trimetaphosphate (TMP) nanoparticles and silver nanoparticles (AgNPs), and to evaluate its antimicrobial activity, surface free energy, TMP and Ag+ release, and cytotoxicity for use as a support in dental tissue. The data were subjected to statistical analysis (p < 0.05). P6 can be incorporated into TMP without altering its properties. In the first three hours, Ag+ was released for all groups decorated with AgNPs, and for TMP, the release only occurred for the P6-TMP-5% and P6-TMP-10% groups. In the inhibition zones, the AgNPs showed activity against both microorganisms. The P6-TMP-2.5%-Ag and P6-TMP-5%-Ag groups with AgNPs showed a greater reduction in CFU for S. mutans. For C. albicans, all groups showed a reduction in CFU. The P6-TMP groups showed higher cell viability, regardless of time (p < 0.05). The developed P6 polymeric matrix impregnated with TMP and AgNPs demonstrated promising antimicrobial properties against the tested microorganisms, making it a potential material for applications in scaffolds in dental tissues.
... The breathability and moisture permeability of the fabric together influences the comfort of human wear [40]. The breathability of different phase change nanofiber membranes was tested according to GB/T 5453, using the evaporation method (positive cup), as shown in Figure 8. ...
To address the thermal comfort needs of the human body, the development of personal thermal management textile is critical. Phase change materials (PCMs) have a wide range of applications in thermal management due to their large thermal storage capacity and their isothermal properties during phase change. However, their inherent low thermal conductivity and susceptibility to leakage severely limit their application range. In this study, polyethylene glycol (PEG) was used as the PCM and polyacrylonitrile (PAN) as the polymer backbone, and the thermal conductivity was increased by adding spherical nano-alumina (Al2O3). Utilizing coaxial electrospinning technology, phase-change thermoregulated nanofiber membranes with a core-shell structure were created. The study demonstrates that the membranes perform best in terms of thermal responsiveness and thermoregulation when 5% Al2O3 is added. The prepared nanofiber membranes have a melting enthalpy of 60.05 J·g−1 and retain a high enthalpy after 50 cycles of cold and heat, thus withstanding sudden changes in ambient temperature well. Additionally, the nanofiber membranes have excellent air permeability and high moisture permeability, which can increase wearer comfort. As a result, the constructed coaxial phase change thermoregulated nanofiber membranes can be used as a promising textile for personal thermal management.
... In their attempts to attain proper utilization of coarse wool grades, Egyptian and Italian teams cooperated together to electro-spin coarse wool keratin/PA6 nanofibers mat, followed by utilization in removal of not only certain metal ions, but also acid and basic dyes from industrial drainage water . Recently, nanofibrous mats with antimicrobial properties were obtained by electro-spinning of Ag-doped keratin/PA6, and successfully used for air filtration (Shen et al. 2019). The Ag-keratin/PA6 composite solution was prepared by adding the keratin powder, extracted from the coarse wool by the reduction method, and AgNO 3 to a formic acid solution of PA6 to obtain electro-spun keratin/PA6 composite solution, as shown in Figure 8. ...
This article review is devoted to throw the light on the unique characteristics of keratin- and sericin-based electro-spun nanofibers which make them suitable for various applications in different fields. The principles of electro-spinning together with the various devices usually used to fabricate nanofibers are also highlighted. The chemistry of keratin and sericin bio-polymers and the methods of extraction from their respective natural resources, such as wool and natural silk fibers, were criticized. Blending of keratin or sericin with various natural and synthetic polymeric materials to improve their rheological properties to obtain electro-spinnable composite suitable for production of functional nano-fibrous mat was discussed. Incorporation of nanosized metals and metal oxides as well as bioactive materials into keratin and sericin-based electro-spun nanofibers imparts new functions to the produced nanofibres. The utilization of these functional nano-fibrous mats in biomedical, filtration and smart textile applications was illustrated. The current status and future prospects of the electro-spun nanofibers were highlighted.
... In situ SEM observation of the pre-damaged sample can give us more information on the internal structure and fiber rearrangement of the nanofiber membranes. PA6 nanofiber membranes are selected, since these are very common in electrospinning research and applications [28][29][30][31][32]. PA6 is relatively simple to electrospun and has been used in many applications such as air filtration [29] and for batteries [30]. ...
Electrospun nanofiber membranes show high potential in various application fields (e.g., filtration, catalysis, and sensing). Nevertheless, knowledge of the mechanical behavior, and more specifically, the deformation of nanofiber membranes is still limited today which can complicate the appliance of nanofiber membranes in applications where they are mechanically loaded. In this paper, we, therefore, analyzed the mechanical behavior of polymeric nanofiber membranes with different fiber orientations (random and aligned) extensively. Polyamide 6 was used as a representative reference polymer for proof-of-concept. Mechanical tests show that all membranes have a coherent deformation behavior at the macroscale up to the point of fracture. Large variations in stiffness, ultimate strength, and ultimate strain were observed between membranes with different fiber orientations (Random: E-mod: 370 ± 34 MP; UTS: 38.5 ± 6.0 MPa; εmax: 30.0 ± 2.8%; Parallel aligned: E-mod: 753 ± 11 MPa; UTS: 55.4 ± 0.8 MPa; εmax: 12.0 ± 0.1%; Perpendicular aligned: E-mod: 24.1 ± 3.7 MPa; UTS:/; εmax: >40%). This shows the versatility and tunability of the mechanical behavior of these nanofiber membranes. At the microscale, the fibrous structure results in deformation mechanisms that resist failure formation and progression when the membrane is mechanically loaded. This results in a high fracture resistance, even for pre-damaged membranes. Realignment of the fibers along the loading direction causes crack tip blunting, locally reinforcing the membrane.
... The lower viscosity of the keratin solution will decrease the strength of the spinning, resulting in spinning failure; in contrast, the higher viscosity of the keratin solution will increase the resistance of spinning, also resulting in spinning failure. Keratin solution alone is difficult to spin, due to its poor viscosity [109]; as such, it is usually necessary to add polymers or prepare high molecular weight keratin, in order to adjust the viscosity of the spinning fluid. Researchers have investigated the compatibility of keratin with various polymers in co-spinning, and successfully developed various types of keratin-based nanofibrous films [110,111]. ...
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.
... Antibacterial mask [53] Keratin/Polyamide 6 E. coli-S. aureus Antibacterial air fi ltration [54] Poly Vinylidene Fluoride (PVDF)/ silver nanoparticles ...
... They proved that PAN/AgNPs nanofi bers, which were fabricated with one cycle loading AgNPs (2247 ppm/g nanofi ber) made ideal membranes for the preparation of a washable antibacterial mask [53]. In another investigation, keratin was extracted from coarse wool and then, an Ag-doped keratin/Polyamide 6 (PA6) composite nanofi ber membrane with enhanced fi ltration and antibacterial performance was prepared by shen et al. [54]. In a study that performed by Swamidoss V. et al. ...
Air pollution is an increasing concern all over the world due to its adverse effects on human health. It claims thousands of lives every year. Hence, the demand for the ventilator, respirator, facemask, body protection, and hospital air filtration has been surging dramatically during the COVID-19 pandemic. Nanofiber membranes with optimal characteristics, such as a high specific surface area and porous microstructure with interconnected pores, can efficiently capture the fine particles (such as bacteria, fungi, virus, etc.). Recently, various types of polymers have been fabricated as electrospun fibrous membranes to be used as an anti-bacterial or anti-viral air filtration media. This review presents a brief overview of air filtration history and its main mechanisms and then the latest research about air filtration with antibacterial and antiviral properties will be reviewed.
... Keratin has a structure like 3D mesh appearance which takes up the form of hydrogels. Keratin advantage is its inherent property which interacts with the polyelectrolyte wound environment and enhances healing (Baolei et al. 2019). Several studies have found that keratin has a better wound healing capacity in diabetic mice. ...
... The application of biopolymers in the biomedical field is extensively reported; however, in recent years, biopolymers have received increasing attention for producing efficient filters, owing to the presence of functional groups, which allow them to possess characteristics such as antibacterial and antiviral properties [80][81][82][83][84][85]. The diverse functional groups that protein-and polysaccharides-based polymers embrace permit them to have different methods of interactions with particles or contaminants [80]. ...
... Soy protein allows an increase in active site for trapping particles or virulent organisms when under acetic conditions, resulting in the deprotonation of acidic and basic groups, such as the carboxyl group, into carboxylate anion (R-COOH to R-COO -) and amine groups converting to amino groups (R-NH 3+ to NH2) [81]. In the study of Jiang et al. [84], soy protein isolate (SPI)/polyamide-6 (PA6)-Ag electrospun meshes exhibit high filtration efficiency for both dust particles and toxic gas, and the addition of AgNPs shows great antimicrobial activity against Escherichia coli and Bacillus subtilis, inhibiting up to 80% of their growth [81]. Cellulose is another biopolymer widely used as biomaterial in several fields, such as biomedical, pharmaceuticals, energy and textile. ...
... Soy protein allows an increase in active site for trapping particles or virulent organisms when under acetic conditions, resulting in the deprotonation of acidic and basic groups, such as the carboxyl group, into carboxylate anion (R-COOH to R-COO -) and amine groups converting to amino groups (R-NH 3+ to NH 2 ) [81]. In the study of Jiang et al. [84], soy protein isolate (SPI)/polyamide-6 (PA6)-Ag electrospun meshes exhibit high filtration efficiency for both dust particles and toxic gas, and the addition of AgNPs shows great antimicrobial activity against Escherichia coli and Bacillus subtilis, inhibiting up to 80% of their growth [81]. Cellulose is another biopolymer widely used as biomaterial in several fields, such as biomedical, pharmaceuticals, energy and textile. ...
The use of electrospun meshes has been proposed as highly efficient protective equipment to prevent respiratory infections. Those infections can result from the activity of micro-organisms and other small dust particles, such as those resulting from air pollution, that impair the respiratory tract, induce cellular damage and compromise breathing capacity. Therefore, electrospun meshes can contribute to promoting air-breathing quality and controlling the spread of such epidemic-disrupting agents due to their intrinsic characteristics, namely, low pore size, and high porosity and surface area. In this review, the mechanisms behind the pathogenesis of several stressors of the respiratory system are covered as well as the strategies adopted to inhibit their action. The main goal is to discuss the performance of antimicrobial electrospun nanofibers by comparing the results already reported in the literature. Further, the main aspects of the certification of filtering systems are highlighted, and the expected technology developments in the industry are also discussed.
... Nanofibers are the type of materials that can be used as a platform in raman spectroscopy [102], in immunoanalysis [103], for air filtration [104] and also as a pseudoenzyme [105]. In a study, AgNPs coupled with poly(dopamine methacrylamide-co-methyl methacrylate) (MADO) nanofiber resulted in wound healing with the synthesis of epidermis on the wound area within two weeks, compared to AgNPs individually, which result in partial healing or required a long time to heal [106][107][108]. ...
Wounds are structural and functional disruptions of skin that occur because of trauma, surgery, acute illness, or chronic disease conditions. Chronic wounds are caused by a breakdown in the finely coordinated cascade of events that occurs during healing. Wound healing is a long process that split into at least three continuous and overlapping processes: an inflammatory response, a proliferative phase, and finally the tissue remodeling. Therefore, these processes are extensively studied to develop novel therapeutics in order to achieve maximum recovery with minimum scarring. Several growth hormones and cytokines secreted at the site of lesions tightly regulates the healing processes. The traditional approach for wound management has been represented by topical treatments. Metal nanoparticles (e.g., silver, gold and zinc) are increasingly being employed in dermatology due to their favorable effects on healing, as well as in treating and preventing secondary bacterial infections. In the current review, a brief introduction on traditional would healing approach is provided, followed by focus on the potential of wound dressing therapeutic techniques functionalized with Ag-NPs.
