FABRICATION OF NANOFIBRES BY ELECTROSPINNING USING KERATIN FROM WASTE CHICKEN FEATHERS, PVA AND AgNPs

Objective: To prepare and characterise keratin from chicken feathers (CF), collected from the slaughter house, and to blend with poly vinly alcohol (PVA) and biosynthesised silver nanoparticles (AgNPs) and to convert into nanofibers by an elctrospinning process. Methods: The extraction of keratin from chicken feathers was done by sodium m-bisulphite. The solution was subjected to ammonium sulphate precipitation to separate keratin. The nanoparticles was synthesised using tridax procumbens. The isolated keratin and PVA was mixed in the ration 0f 50:50 with 1 ml of biosynthesised nanoparticles was blended and made into nanofibres by electrospinning technique. Results: The precipitated protein was analysed using FT-IR analysis confirming the presence of β-keratin in the sample isolated from chicken feathers and the concentration of keratin was estimated to be 1.85 g/ml. PVA solution with 4% w/v had the best film forming ability. The solution containing keratin, PVA and silver nanoparticles was prepared in various proportions. These solutions when subjected to electrospinning, fibrous network was observed in 50:50 (PVA: Keratin) ratio with 1 ml of synthesised silver nanoparticle solution. Hydrogen bonding between keratin and PVA indicated in the XRD analysis showed successful film forming of the nanofiber, the DSC analysis also showed similar results as the obtained peak was at 214 °C which is in between the characteristic heat degradation temperature of both the keratin and PVA. The thermogravimetric analysis (TGA) showed high thermal stability as the complete degradation of the nanofiber was observed at 420 °C. Incorporation of metal nanoparticles by herbal approach using tridax procumbens in the nanofibers provided the antimicrobial properties. The nanofibres obtained by electrospinning process appeared stable and continous for solutions containing no more than 50% wt of CF. The average diameter of the nanofibres increased as the CF content increased. Conclusion: Keratin isolated from the waste chicken feathers impregnated with biosyntheised silver nanoparticles using tridax procumbens and PVA can be converted into nanofibers by electrospinning process. Thus, the biocomposite nano fibers are shown as a novel eco-friendly material that must be adequately applied in the development of green composites for the biomedical applications such as wound dressings

Controlled De-Cross-Linking and Disentanglement of Feather Keratin for Fiber Preparation via a Novel Process

Pure protein fibers were fabricated from chicken feathers via a potentially green process. In the last several decades, efforts have been made to produce keratin-based industrial products, especially fibers. However, the methods of producing keratin fibers directly from chicken feathers could not be repeated. In this research, protein fibers from chicken feathers were developed using chemicals that could be either derived from renewable resources or facilely recycled. Backbones of keratin were preserved after cleavage of disulfide bonds using cysteine. Sodium dodecyl sulfate (SDS) was applied to dissolve keratin for spinning. Increasing SDS concentration intensified the ordered conformation of keratin, first increased and then decreased the viscosity of solution, suggesting continuous disentanglement of keratin molecules and enhancement in inter- and intramolecular electrical repulsion. Diameters of the obtained fibers as small as 20 μm also proved good drawability of the keratin solution. Change in crystallinity indices was found to be consistent with that of tensile properties of the keratin fibers. In summary, regenerated fibers were successfully produced as linear keratin with preserved backbones that could be untangled and aligned in a controlled manner

Protein-Based Fiber Materials in Medicine: A Review

Fibrous materials have garnered much interest in the field of biomedical engineering due to their high surface-area-to-volume ratio, porosity, and tunability. Specifically, in the field of tissue engineering, fiber meshes have been used to create biomimetic nanostructures that allow for cell attachment, migration, and proliferation, to promote tissue regeneration and wound healing, as well as controllable drug delivery. In addition to the properties of conventional, synthetic polymer fibers, fibers made from natural polymers, such as proteins, can exhibit enhanced biocompatibility, bioactivity, and biodegradability. Of these proteins, keratin, collagen, silk, elastin, zein, and soy are some the most common used in fiber fabrication. The specific capabilities of these materials have been shown to vary based on their physical properties, as well as their fabrication method. To date, such fabrication methods include electrospinning, wet/dry jet spinning, dry spinning, centrifugal spinning, solution blowing, self-assembly, phase separation, and drawing. This review serves to provide a basic knowledge of these commonly utilized proteins and methods, as well as the fabricated fibers’ applications in biomedical research

Synthesis and characterization of wound healing hydrogel using keratin protein from chicken feathers

Poultry industries produce a large amount of feather waste, which harm the environment and human health. On the other hand, chicken feathers primarily contain keratin protein, which can be exploited to produce products for biomedical applications. In the present research, keratin was extracted from chicken feathers and was applied to prepare the hydrogel films for wound healing applications. Some biopolymers were used to prepare two different hydrogel films, such as polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) and corn starch, using the freeze-thawing technique at temperature -20°C. All biopolymers used in this study are inexpensive, non-toxic, and have been successfully applied in various biomedical applications. The first formulation, namely KS-hydrogels were prepared using keratin, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP) and corn-starch. The second formulation, namely K-hydrogels were prepared using keratin, polyvinyl alcohol (PVA), and polyvinylpyrrolidone (PVP). The effect of keratin in hydrogel films for both samples was examined by Fourier-transform infrared spectroscopy (FTIR), confirmed the presence of keratin, scanning electron microscope (SEM) examined surface morphology, and thermogravimetric analysis (TGA) showed thermal stability was affected with different concentrations of keratin protein. The porosity of the hydrogel decreased for KS-70 and K-70 hydrogels at 33.57% and 45.22%, respectively, due to their relatively high interconnecting and low porous structure due to their low water content with high keratin content. The swelling ratio of KS70 and K70 hydrogels and 30.66% and 31.58 % after 1440 min due to its relatively increased crosslinking density with high keratin content. On the other hand, tensile strength (stress vs strain) has seen improvement with the increase of the keratin protein content into hydrogel films. Furthermore, it was found that K-hydrogel films were better than KS-hydrogel films because K-hydrogel films provided an appropriate hardness for using potential wound healing applications. Moreover, keratin release increased with increasing keratin content; the highest release was 95.72% in K70 after 96 hr on the KS-hydrogel films and K-hydrogel films release was 81% in K70 after 96 hr Higuchi square root model best predicted the keratin release behaviour. The Higuchi square root was the optimal model of keratin kinetics release for all the hydrogel films. The optimal conditions for hydrogel film synthesis were determined using response surface methodology (RSM) with four selected parameters, including (A, 30-70 v/v %), PVA/PVP ratio (B, 30-70 v/v %), freeze and thawing (C, 3-7 cycles), and mixing temperature (D, 50-70 °C). The model determined that the optimal conditions for the best formation were 50% keratin content, 50% PVA/PVP, five freeze-thaw cycles, and a mixing temperature of 60°C. ANOVA demonstrated the model is significant and has a p-value less than 0.05, with the R2 was 97.3. In vivo model on the rabbits indicated that keratin-based hydrogel film could accelerate wound healing compared with other groups after 19 days. Dependence on the results obtained in this study, the keratin hydrogel film was successfully prepared for potential wound healing applications

Chapter 34 - Biocompatibility of nanocellulose: Emerging biomedical applications

Nanocellulose already proved to be a highly relevant material for biomedical applications, ensued by its outstanding mechanical properties and, more importantly, its biocompatibility. Nevertheless, despite their previous intensive research, a notable number of emerging applications are still being developed. Interestingly, this drive is not solely based on the nanocellulose features, but also heavily dependent on sustainability. The three core nanocelluloses encompass cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial nanocellulose (BNC). All these different types of nanocellulose display highly interesting biomedical properties per se, after modification and when used in composite formulations. Novel applications that use nanocellulose includewell-known areas, namely, wound dressings, implants, indwelling medical devices, scaffolds, and novel printed scaffolds. Their cytotoxicity and biocompatibility using recent methodologies are thoroughly analyzed to reinforce their near future applicability. By analyzing the pristine core nanocellulose, none display cytotoxicity. However, CNF has the highest potential to fail long-term biocompatibility since it tends to trigger inflammation. On the other hand, neverdried BNC displays a remarkable biocompatibility. Despite this, all nanocelluloses clearly represent a flag bearer of future superior biomaterials, being elite materials in the urgent replacement of our petrochemical dependence

Protein materials as sustainable non- and minimally invasive strategies for biomedical applications

Protein-based materials have found applications in a wide range of biomedical fields because of their biocompatibility, biodegradability and great versatility. Materials of different physical forms including particles, hydrogels, films, fibers and microneedles have been fabricated e.g. as carriers for drug delivery, factors to promote wound healing and as structural support for the generation of new tissue. This review aims at providing an overview of the current scientific knowledge on protein-based materials, and selected preclinical and clinical studies will be reviewed in depth as examples of the latest progress within the field of protein-based materials, specifically focusing on non- and minimally invasive strategies mainly for topical application

Nanofibrous Scaffolds for Skin Tissue Engineering and Wound Healing Based on Nature-Derived Polymers

Nanofibrous scaffolds belong to the most suitable materials for tissue engineering, because they mimic the fibrous component of the natural extracellular matrix. This chapter is focused on the application of nanofibers in skin tissue engineering and wound healing, because the skin is the largest and vitally important organ in the human body. Nanofibrous meshes can serve as substrates for adhesion, growth and differentiation of skin and stem cells, and also as an antimicrobial and moisture-retaining barrier. These meshes have been prepared from a wide range of synthetic and nature-derived polymers. This chapter is focused on the use of nature-derived polymers. These polymers have good or limited degradability in the human tissues, which depends on their origin and on the presence of appropriate enzymes in the human tissues. Non-degradable and less-degradable polymers are usually produced in bacteria, fungi, algae, plants or insects, and include, for example, cellulose, dextran, pullulan, alginate, pectin and silk fibroin. Well-degradable polymers are usually components of the extracellular matrix in the human body or at least in other vertebrates, and include collagen, elastin, keratin and hyaluronic acid, although some polymers produced by non-vertebrate organisms, such as chitosan or poly(3-hydroxybutyrate-co-3-hydroxyvalerate), are also degradable in the human body

Keratin: dissolution, extraction and biomedical application

Keratinous materials such as wool, feathers and hooves are tough unique biological co-products that usually have high sulfur and protein contents. A high cystine content (7–13%) differentiates keratins from other structural proteins, such as collagen and elastin. Dissolution and extraction of keratin is a difficult process compared to other natural polymers, such as chitosan, starch, collagen, and a large-scale use of keratin depends on employing a relatively fast, cost-effective and time efficient extraction method. Keratin has some inherent ability to facilitate cell adhesion, proliferation, and regeneration of the tissue, therefore keratin biomaterials can provide a biocompatible matrix for regrowth and regeneration of the defective tissue. Additionally, due to its amino acid constituents, keratin can be tailored and finely tuned to meet the exact requirement of degradation, drug release or incorporation of different hydrophobic or hydrophilic tails. This review discusses the various methods available for the dissolution and extraction of keratin with emphasis on their advantages and limitations. The impacts of various methods and chemicals used on the structure and the properties of keratin are discussed with the aim of highlighting options available toward commercial keratin production. This review also reports the properties of various keratinbased biomaterials and critically examines how these materials are influenced by the keratin extraction procedure, discussing the features that make them effective as biomedical applications, as well as some of the mechanisms of action and physiological roles of keratin. Particular attention is given to the practical application of keratin biomaterials, namely addressing the advantages and limitations on the use of keratin films, 3D composite scaffolds and keratin hydrogels for tissue engineering, wound healing, hemostatic and controlled drug release.info:eu-repo/semantics/publishedVersio

Development and Characterization of Electrospun Wound Dressings Containing Birch Bark Extract

Ein effizientes und einfach zu handhabendes Wundmanagement ist immer noch eine große Herausforderung. In unserem täglichen Leben wäre es äußerst wünschenswert, einfache, akzeptable Verbandmaterialien zu haben, die einerseits direkt zur Abdeckung von Wunden und andererseits zur Beschleunigung der Wundheilung verwendet werden können. Ein Triterpentrockenextrakt (TE) aus der Birkenrinde kann nachgewiesenermaßen den Wundheilungsprozess beschleunigen. Daher war das Hauptziel dieser Arbeit die Entwicklung von elektrogesponnenen Wundauflagen mit TE als aktiver Komponente. Das Grundkonzept bestand darin, kolloidale Dispersionen von TE in eine Polyvinylalkohol (PVA)-Matrix einzuarbeiten und Wundauflagen durch Elektrospinnen herzustellen. Die TE-Partikel weisen jedoch einzigartige Strukturen auf, die mit herkömmlichen Verfahren nicht zerkleinert werden können. Selbst wenn hochenergetische Dispersionstechniken eingesetzt werden, lassen sich in öligen oder wässrigen Dispersionen keine Partikel im kolloidalen Größenbereich herstellen. Dies stellt ein Hindernis für eine einfache Verwendung des TE in die PVA-Matrix beim Elektrospinnen dar. Im ersten Teil dieser Doktorarbeit wurden kolloidale Dispersionen konzipiert, die TE, Sonnenblumenöl, Phospholipide (PL90H) und Wasser enthalten. Zunächst wurde eine Bestimmung der Grenzflächenspannung durchgeführt, um den potenziellen Einfluss von PL90H im Dispersionsprozess und seine Wechselwirkung mit TE zu untersuchen und zu verstehen. Es wurde eine synergistische Wechselwirkung zwischen PL90H und TE beobachtet. Durch ein optimiertes stufenweises Homogenisierungsverfahren war es möglich, kolloidale Dispersionen mit Partikelgrößen unter 1 µm herzustellen. Im zweiten Teil wurden bioaktive elektrogesponnene Wundauflagen entwickelt und charakterisiert, die TE kontrolliert freisetzen können. Elektrospinnparameter zur Herstellung von Wundauflagen wurden untersucht und optimiert. Insbesondere die Variation von Konzentration und Molekulargewicht des Polymers hatte einen signifikanten Einfluss auf die Spinnbarkeit, die rheologischen Eigenschaften der Polymerlösung und die resultierenden Fasereigenschaften. Wir konnten zeigen, dass bioaktive Wundauflagen mit glatten und gleichmäßigen Fasern hergestellt werden können. In-vitro-Freisetzungs- und Ex vivo-Permeationsuntersuchungen ergaben, dass elektrogesponnene Wundauflagen Betulin über einen Zeitraum von 72 Stunden freisetzen können. Durch die Veränderung der Komponenten von kolloidalen Dispersionen, nämlich PL90H und Sonnenblumenöl, kann die Freisetzung von Betulin gesteuert werden. Ex-vivo-Wundheilungsergebnisse deuten darauf hin, dass die Behandlung mit nanofaserigen Wundauflagen, insbesondere mit niedrigen TE-Mengen, eine überragende und beschleunigte Wundheilung erzielte. Als alternative Formulierung zur Wundtherapie wurden in der letzten Phase der Arbeit TE-haltige Filme mittels Solvent Casting Methode hergestellt. Aus den in-vitro-Freisetzungs- und ex vivo-Wundheilungsstudien ergaben diese Filme positive Erkenntnisse, sodass diese ebenfalls als Wundauflagen dienen können. Dennoch waren TE-basierte elektrogesponnene Wundauflagen im Vergleich zu den gegossenen Filmen bei der Wundheilung überlegen. Mit den aktuellen Entwicklungen in der Elektrospinntechnologie ist es möglich, elektrogesponnene Wundauflagen innerhalb kürzerer Zeit auf industrieller Ebene herzustellen. Andererseits könnte die Herstellung gegossener Filme auch als einfache Alternative zur Abdeckung von Wunden dienen. In-vivo-Studien könnten für die zukünftige Umsetzung der entwickelten TE-Wundauflagen unter Nutzung der Grundlage dieser Arbeit von wesentlicher Bedeutung sein. Dieses Projekt zeigt deutlich, dass wir durch einen innovativen Ansatz bioaktive Wundauflagen entwickelt haben, die ein alternatives pharmazeutisches Formulierungspotenzial für die Wundtherapie in naher Zukunft darstellen.Wound care is a challenging task in our daily lives. Therefore, it would be highly desirable to have simple, acceptable dressing materials that can be used directly to cover wounds and accelerate wound healing. Birch bark triterpene extract (TE) has the ability to accelerate the wound healing process. Thus, the main goal of this work was to develop novel electrospun wound dressings with TE as the active principal. The underlying concept was to blend colloidal dispersions of TE with polyvinyl alcohol (PVA) matrix and produce wound dressings by electrospinning. However, TE particles exhibit unique structures which cannot be crushed by common techniques to reach particles in the colloidal size range even when high energy dispersion techniques are used. This represents an obstacle for a simple incorporation of TE into the PVA matrix through electrospinning. In the first part of this PhD thesis, the colloidal dispersions were designed to contain TE, sunflower oil, phospholipids (PL90H) and water. First, an interfacial tension analysis was performed to investigate and understand the potential influence of PL90H in the dispersion process and its interaction with TE. A synergistic interaction between PL90H and TE was also discussed. An optimized stepwise homogenization process made it feasible to produce colloidal dispersions with particle sizes below 1 µm. In order to design and develop novel wound dressings as delivery devices capable of releasing TE, we focused on emulsion electrospinning technique for bioactive scaffold production. Electrospinning parameters to fabricate the dressings were investigated and optimized. In particular, the varying of concentration and molecular weight of the polymer had a significant effect on spinnability, rheological properties of polymer solution and the resulting fiber properties. We showed that bioactive wound dressings with smooth and uniform fibers can be produced. Cumulative in vitro drug release and ex vivo permeation profiles showed that TE-loaded scaffolds can release Betulin in a sustained release manner. By adjusting components of the colloidal dispersions, namely PL90H and sunflower oil, the release of Betulin can be controlled. Amazingly, ex-vivo wound healing results indicated that treatment with nanofibrous wound dressings especially with low TE amounts achieved superlative and accelerated wound healing recovery. In the last phase of this thesis, films containing colloidal dispersions were produced using the solvent casting method, for possible alternative formulations towards wound therapy. From the in vitro drug release and ex vivo wound healing studies, these films gave positive insights to serve as additional wound dressings. Nevertheless, TE-loaded electrospun wound dressings were superior to such cast films in wound healing. With the current developments in electrospinning technology, it is possible to manufacture electrospun dressings at industrial level within shorter times. On the other hand, fabrication of such cast films could also serve as efficient dressings for covering wounds. In vivo studies could be essential for future translation of the developed TE dressings while utilizing the basis of this work. This project clearly shows that through an innovative approach we have developed bioactive wound dressings that present an alternative pharmaceutical formulation potential for wound therapy in the near future

Perspective Chapter: Design and Characterization of Natural and Synthetic Soft Polymeric Materials with Biomimetic 3D Microarchitecture for Tissue Engineering and Medical Applications

Continuous work and developments in biomedical materials used in three-dimensional (3D) bioprinting have contributed to significant growth of 3D bioprinting applications in the production of personalized tissue-repairing membrane, skin graft, prostheses, medication delivery system, and 3D tissue engineering and regenerative medicine scaffolds. The design of clinic products and devices focus on new natural and synthetic biomedical materials employed for therapeutic applications in different 3D bioprinting technologies. Design and characterization of natural and synthetic soft polymeric materials with biomimetic 3D microarchitecture were considered. The natural soft polymeric materials would focus on new design bioinspired membranes containing supercritical fluids-decellularized dermal scaffolds for 3D bioprinting potential applications. Synthetic soft polymeric materials would focus on bioinspired polyvinyl alcohol (b-PVA) matrix with structural foam-wall microarchitectures. Characterization, thermal stability, and cell morphology of the b-PVA and the corresponding collagen-modified b-PVA were employed to evaluate their potential tissue engineering applications. Also, the b-PVA materials were conductive to HepG2 cells proliferation, migration, and expression, which might serve as a promising liver cell culture carrier to be used in the biological artificial liver reactor. TGA, DTG, DSC, SEM, and FTIR were employed to build up the effective system identification approach for biomimetic structure, stability, purity, and safety of target soft matrix