Claudia Vineis

Study on Cast Membranes and Electrospun Nanofibers Made from Keratin/Fibroin Blends

Keratin regenerated from wool and fibroin regenerated from silk were mixed in different proportions using formic acid as the common solvent. Both solutions were cast to obtain films and electrospun to produce nanofibers. Scanning electron microscopy investigation showed that, for all electrospun blends (except for 100% keratin where bead defects are present), the fiber diameter of the mats ranged from 900 (pure fibroin) to 160 nm (pure keratin). FTIR and DSC analysis showed that the secondary structure of the proteins was influenced by the blend ratios and the process used (casting or electrospinning). Prevalence of beta-sheet supramolecular structures was observed in the films, while proteins assembled in alpha-helix/random coil structures were observed in nanofibers. Higher solution viscosity, thinner filaments, and differences in the thermal and structural properties were observed for the 50/50 blend because of the enhanced interactions between the proteins.

Antibacterial efficacy of polypyrrole in textile applications

This paper describes application and evaluation of polypyrrole as an antibacterial polymer. Polypyrrole was produced embedding two doping agents: chloride and dicyclohexyl sulfosuccinate ions. Stability of the antibacterial efficacy of polypyrrole deposited on cotton fabrics was assessed before and after three different kinds of washing (namely, laundering with anionic and non-ionic detergents and dry-cleaning). Polypyrrole showed excellent antibacterial properties (100 % of bacterial reduction) against Escherichia coli for both doping agents. Treated fabrics were further characterised by scanning electron microscopy, energy dispersive X-ray analysis and infrared spectroscopy. The antibacterial efficacy diminished after launderings with anionic and non-ionic detergents because of two different mechanisms: the neutralisation of positive charges under alkali conditions (dedoping), and a partial removal of polypyrrole by abrasion and surfactant action. After dry-cleaning, polypyrrole embedding chloride and dicyclohexyl sulfosuccinate ions still showed excellent antibacterial efficacy. Moreover, scanning electron microscopy investigations were used to intuitively explain the bactericidal mechanism of polypyrrole on Escherichia coli bacteria.

Chitosan coated cotton gauze for antibacterial water filtration

Communicable diseases can be transmitted by contaminated water. Water decontamination process is fundamental to eliminate microorganisms. In this work, cotton gauzes were coated with chitosan using an UV-curing process or cationized by introduction of quaternary ammonium groups and tested, in static and dynamic conditions, as water filter for biological disinfection against both Gram-negative and Gram-positive bacteria. Both materials showed good antibacterial activity, in static assessment, instead in dynamic conditions, chitosan treated gauze showed a high antimicrobial efficiency in few seconds of contact time. This composite could be a good candidate for application as biological filter.

Multifunctional finishing of wool fabrics by chitosan UV-grafting: An approach

The aim of this study was the surface modification of wool fibers to confer a multifunctional finishing to the fabrics, improving the textile value and its applications without damage of comfort properties. The attention was focused on an economical and environmental friendly process to obtain an effective treatment with good durability to washing. Chitosan in acetic acid solution was applied by padding, and grafted by ultraviolet radiation, through radical reactions promoted by a photoinitiator. 2% chitosan grafted was enough to confer satisfactory antimicrobial activity (67% reduction of Escherichia coli) after an oxidative wool pre-treatment and 1h impregnation at 50 °C. Moreover treated wool fabrics showed a strong dyeability increase toward acid dye. However the evaluation of the treatment durability to laundering showed different behavior depending on the nature of the surfactants. Finally, anti-felting properties with respect to untreated fabrics were revealed, while no effect was shown toward anti-pilling properties.

Microwave-assisted chemical-free hydrolysis of wool keratin

Wool fibers were submitted to “green hydrolysis” with superheated water in a microwave reactor, in view of the potential exploitation of keratin-based industrial and stock-farming wastes. The liquid fraction was separated by filtration from the solid fraction, which consists mainly of small fragments of wool fibers and other insoluble protein aggregates. The liquid fraction contains free amino acids, peptides and low molecular weight proteins, with a small amount of cystine and lanthionine, and has a different secondary structure when compared with keratins extracted from wool via reductive or oxidative methods. Cleavage of the cystine disulfide bonds without the use of harmful, often toxic, reductive or oxidative agents allows the extraction of protein material from keratin wastes, offering the possibility of larger exploitation and valorization.

Keratin-based Nanofibres

The interest in biopolymers from renewable resources as alternatives to polymers made from oil and other fossil resources has been increasing over the years. Biopolymers are also considered environmentally friendly over their entire live-cycle. There is much recent literature on carbohydrates and proteins derived from plants and animals and polyesters made from the fermentation of plant material. As to whether it is ethically justifiable to convert valuable foodstuffs into commodities is open to question. The focus here is on keratin, one of the most abundant and mostly unexploited non-food proteins, being the major component of hair, feathers, nails and horns of mammals and birds. In spite of their important and interesting characteristics keratin wastes represent a rather complicated disposal challenge because burning for fuel is inefficient and polluting due to the high sulphur content (3-4% wt). The total amount of keratin (including fibre by-products from the wool textile industry, poor quality raw wools from farms and butchery waste) has been estimated worldwide at more than 5 million tonnes per year (Barone et al., 2005). Ground horn and nail is used as a nitrogenous fertilizer for gardening and, more recently, has been processed by caustic hydrolysis to produce biodegradable surfactants for fire extinguisher foams. However, most keratin wastes made from unserviceable wools and feathers from poultry are not valorised and are simply disposed of (Martinez-Hernandez et al., 2007; Schmidt, 1998). Pooling and processing into biopolymers might be a better way of exploiting such a large quantity of protein biomass. Keratin-based materials can be used in biotechnological and biomedical fields for tissue engineering and the production of affinity membranes, due to their biocompatibility, their ability to support fibroblast growth and absorb heavy metal ions and volatile organic compounds (VOCs). Transforming keratin into nanofibres by electrospinning combines the aforementioned properties of keratin with the high surface to volume ratio and the high porosity of nano-structured textiles. This may be an original and promising approach for the fabrication of scaffolds for tissue engineering and filtration devices. Keratin distinguishes itself from other structural proteins by the quantity of cysteine residues in the protein molecules (7-20% of the total amino acid residues). In particular, cysteine amino acids form inter and intra molecular disulphide bonds (cysteine residues) giving rise to a compact three-dimensional structure that confers a high stability to the protein (Dowling et al., 1986). Because of their low molecular weight (9–60 kDa), keratin-based materials have poor mechanical properties. Moreover, like most natural polymers, keratin is not thermoplastic. For electrospinning keratin should be blended with suitable polymers using common,

Nanogrooves and keratin nanofibers on titanium surfaces aimed at driving gingival fibroblasts alignment and proliferation without increasing bacterial adhesion

Periimplantitis and epithelial downgrowth are nowadays the main conditions associated to transmucosal dental implants. Gingival fibroblasts can play an important role in periimplantitis because they are the promoters of the inflammatory process and eventual tissue homeostasis and destruction. Moreover, the related inflammatory state is commonly driven also to counteract bacteria implants colonization. In the present research, a new technology based on mechanically produced nanogrooves (0.1-0.2μm) and keratin nanofibers deposited by electrospinning has been proposed in order to obtain titanium surfaces able to drive gingival fibroblasts alignment and proliferation without increasing bacterial adhesion. The prepared surfaces have been characterized for their morphology (FESEM), chemical composition (FTIR, XPS), surface charge (zeta potential) and wettability (contact angle). Afterwards, their performances in terms of cells (human primary gingival fibroblasts) and bacteria (Staphylococcus aureus) adhesion were compared to mirror-like polished titanium surfaces. Results revealed that gingival fibroblasts viability was not negatively affected by the applied surface roughness or by keratin nanofibers. On the opposite, cells adhesion and spread were strongly influenced by surface roughness revealing a significant cell orientation along the produced nanogrooves. However, the keratin influence was clearly predominant with respect to surface topography, thus leading to increased cells proliferation on the surfaces with nanofibers, disregarding the presence of the surfaces grooves. Moreover, nor nanogrooves nor keratin nanofibers increase bacterial biofilm adhesion in comparison with mirror polished surfaces. Thus, the present research represents a promising innovative strategy and technology for a surface modification finalized to match the main requirements for transmucosal dental implants.

Electrospinning of polyamide 6/modified-keratin blends

Abstract Protein material resulting from chemical free steam explosion of wool was mixed in different proportion with polyamide 6 in formic acid. The viscosity of the blend solutions decreases with the increase of the protein amount in the blend. Nanofibres produced by electrospinning of these polymer blends show an increase of the filament diameters with increasing protein amounts, except for the 30/70 v/v polyamide 6/protein blend, where nanofibres with “beads” defects were produced. In blend films produced by casting, polyamide 6 crystallize in the form of large spherulites prevalently in the α crystalline structure, while protein is totally amorphous and tends to segregate in the course of drying at room temperature. Otherwise, in electrospun nanofibres polyamide 6 and protein show a better miscibility as suggested by spectroscopic and thermal analysis and polyamide 6 shows a higher thermal stability. Moisture regain and water solubility of blend cast films and electrospun nanofibres respectively were also determined.

Anti-keratin monoclonal antibodies for identifying animal hair fibers

Type II keratins from cashmere are used as antigens to produce species-specific monoclonal antibodies for fiber identification purposes. Balb/c mice are immunized with the keratins purified by two-dimensional preparative gel electrophoresis. Hybridoma clones showing high immunological responses are subcloned by limiting dilution and then expanded to obtain antibodies in large amounts. When the antibodies are screened by two-dimensional immunoblotting for immunoreactivity with keratins isolated from cash mere and wool, several differences are detected, both quantitative and qualitative. Al though further work is needed to develop routine analytical protocols, the preliminary results reported in this paper appear to be extremely promising, and our approach could contribute to solving the problem of the objective identification of cashmere and other speciality animal fibers.

A UPLC/ESI–MS method for identifying wool, cashmere and yak fibres:

A new objective method has been developed for the identification of animal hair fibres, in particular wool, cashmere and yak. Enzymatic digestion of keratin extracted from these fibres and peptide analysis by ultra-performance liquid chromatography/electrospray–mass spectrometry (UPLC/ESI–MS) allows not only qualitative determination of the presence of fibres derived from these species but also a quantitative assessment of the relative percentages present in blends. Such an analysis will provide reliable objective data about the authenticity of commercial products. The effectiveness of the UPLC/ESI–MS method was assessed by analysing known samples of these fibres and confirmed using unknown wool/cashmere/yak blends, and the results were compared with those obtained by SEM method IWTO 58–00.