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Polypyrrole (PPy) nanoparticles (NPs) are used for the coating of materials, such as textiles, with biomedical applications, including wound care and tissue engineering, but they are also promising antibacterial agents. In this work, PPy NPs were used for the spray-coating of textiles with antimicrobial properties. The functional properties of the materials were verified, and their safety was evaluated. Two main exposure scenarios for humans were identified: inhalation of PPy NPs during spray (manufacturing) and direct skin contact with NPs-coated fabrics (use). Thus, the toxicity properties of PPy NPs and PPy-coated textiles were assessed by using in vitro models representative of the lung and the skin. The results from the materials’ characterization showed the stability of both the PPy NP suspension and the textile coating, even after washing cycles and extraction in artificial sweat. Data from an in vitro model of the air–blood barrier showed the low toxicity of these NPs, with no alteration of cell viability and functionality observed. The skin toxicity of PPy NPs and the coated textiles was assessed on a reconstructed human epidermis model following OECD 431 and 439 guidelines. PPy NPs proved to be non-corrosive at the tested conditions, as well as non-irritant after extraction in artificial sweat at two different pH conditions. The obtained data suggest that PPy NPs are safe NMs in applications for textile coating.

Wool keratin (natural resource) and citric acid (effective preservative) were mixed in water to produce a transparent film for application in active packaging. This film showed excellent biocidal effect, high elongation value (600%) and little loss of keratin after immersion in water. The capability of citric acid to bind keratin macromolecules by hydrogen bonds is probably responsible for the improvement of film's extensibility. On the other hand, the study of FT-IR spectrum allows understanding that the presence of citric acid in aqueous solution enhances the content of alpha helix structure in the film, with a reduction in the amount of side chain and disordered conformations in the macromolecular structure. Carrot shelf-life was qualitatively improved with this film in comparison with a commercial film for preserving food. Consequently, this film can have possible application for food packaging as a substitute of synthetic polymers replacing them with a natural, environmental friendly and renewable resource.

The method based on the ultra-performance liquid chromatography coupled with electrospray mass spectrometry (UPLC/ESI–MS) instrument was used for the identification and quantification of the most commercial Bovidae fibres (wool, cashmere and yak). In the present paper, this method was developed and validated by the authors and confirmed by many analyses of, known and unknown, wool/cashmere/yak blends at different stages of manufacture (fibres, slivers, yarns, fabrics, and raw materials) and with different treatments (dyed, depigmented, bleached, finished forms).

Curcuma powder was used to dye cotton and polyamide 6,6 fabrics in order to produce textile-based optical pH sensors. Both fabrics showed a bright yellow color after dyeing and demonstrated color changes (towards red) when contacted with basic solutions. Color change and sensitivity differ for cotton and for polyamide. Curcuma-dyed cotton shows color changes in particular in the range of pH between 6.5 and 8.5, whilst curcuma-dyed polyamide shows a wider pH range: from 8.5 to 13.0. The stability of pH sensing to washing was evaluated. Three different kinds of washing agents were used in order to simulate the real life conditions of a garment or a cloth. Standard test methods were used when available for washing tests. The pH sensing of the curcuma-dyed fabrics demonstrated an excellent fastness to all kinds of washing. Ionic strength of the solution does not affect the color changes. Moreover, color reversibility of the fabrics was proven, too. Color change and reversibility of the fabrics was assessed by an UV-visible spectrophotometer. Spectral changes were observed at 540 nm for curcuma-dyed cotton, and at 487 and 574 nm for polyamide.

Chitosan was grafted on the surface of a cotton gauze (20, 50, and 100 mg chitosan g(-1) cotton) to improve its stability in aqueous solutions. The adsorption of hexavalent chromium ions from water on the grafted chitosan was evaluated to determine, by means of linear and nonlinear models, the kinetic and isotherm adsorption of the process. The kinetics of pseudo second-order, pseudo first-order, and adsorption isotherms type II were obtained, that is, a monolayer adsorption on nonporous adsorbents with physical adsorption was present. The most probable energy of adsorption corresponded to a physisorption with hydrogen bond interactions between chromium ions and ammonium groups. Moreover, three different cross-sectional areas of hexavalent chromium ions were calculated and used to estimate the specific surface area employed by active sites to adsorb metal ions in terms of chitosan or cotton mass. Finally, the percentage of the area occupied by chromium ions on the surface was estimated by dividing the resulting specific surface area in terms of cotton mass by the specific surface area of cotton reported in literature. As a result, it was determined that the occupied area is between 6% (for 20 mg chitosan g(-1) cotton)-24% (for 100 mg chitosan g(-1) cotton) from the total area of cotton.

Electrospinning is a versatile and promising technology for the production of polymer-based nanofibres. Composite nanofibres suitable for filtration of air and water have been developed by merging biopolymer processing and sol-gel techniques using electrospinning technology. A fine control of large-scale nanofibre formation is required to achieve reliable transfer of electrospinning-based processes into relevant industrial environments. The main goals of this work were the production of innovative multifunctional filter media (high-efficiency filtration, biocidal, self-cleaning, photo-catalytic, reactive, adsorbent properties) by integrating nanofibre membranes with inorganic nanoparticles and developing an electrospinning plant integrating sensors able to detect electrospinning fault and electrostatic alteration during the process.

Animal hair fibres like wool, cashmere and yak are obtained from domestic mammals of the genera Ovis, Capra and Bos. Cashmere fibres are valuable natural raw materials used by the fashion industry for manufacturing high quality luxury textiles, and as such are distinct from fibres derived from sheep and yak. Leading companies in the textile sector need objective and precise analytical methodologies able to univocally identify and quantify animal hair fibers present in textile articles, to guarantee that no falsification occurs, especially when cheaper fibers, like wool and yak, are blended with expensive fibers, like cashmere. The traditional and most used methods for identifying animal fibres are Light Microscopy (LM) and Scanning Electron Microscopy (SEM). In Figure 1 are reported SEM images of wool, cashmere and yak fibers. These techniques are subjective depending on the expertise of the operator and often are affected by physical and chemical treatments to which the fibers have been submitted during textile processing. Several methods have been studied to improve the objectivity and accuracy of the results of the animal fiber blend identification, like methods based on the extraction and analysis of DNA [1] or based on specie-specific monoclonal antibodies [2]. Nevertheless, the results obtained are often affected by chemical treatment such as bleaching, dyeing and depigmentation. To remedy these problems, in collaboration with the Department of Food and Drug of the University of Parma, we developed a new method for qualitative and quantitative analysis of animal hair fibers. The method based on electrospray (ESI) mass spectrometry (MS) combined with liquid chromatography (LC) follows a proteomic approach to assess molecular markers for wool, cashmere and yak fibers identification and quantification [1-3]. Keratin from sheep, cashmere goat and yak are similar but not identical, because in some specific parts there are amino acidic variants resulting in specific peptide-markers which can be used to distinguish each animal fiber. These markers have been successfully used not only for qualitative analysis of wool, cashmere and yak blends, but also for quantitative ones.

Polypyrrole (PPy) is a conjugated polymer that shows excellent electrical conductivity, as well as antibacterial properties. The electrical conductivity is an intrinsic property of PPy because of its conjugated chemical structure. Moreover, the bioactivity is likely due to the presence of positive charges along the backbone chain able to open the membrane cell of bacteria [1,2].PPy can be deposited to textiles by a direct chemical deposition [2] to produce heating fabrics. However, the separation between polymer synthesis and fabric coating would lead to benefits in terms of productivity, evenness, cost, wastewater and chemicals usage. This process is useful in particular for antibacterial textiles that requires low amount of coating to be effective.In this work, chemical synthesis of PPy was carried out following two methods: 1) in presence of the fabrics in the polymerization bath in order to produce heating fabrics with high amount of PPy; 2) without a textile substrate in order to produce a PPy dispersion in water suitable for a following deposition on fabrics by ultrasound or spraying.Method 1. Fabrics were cut to 20 x 20 cm and plunged in a 0.18 M solution of ferric sulphate (liquor ratio 50:1), then the monomer was added under stirring to a concentration of 0.06 M. The samples were pulled out from the polymerization bath after 4 h, rinsed in cold water, gently squeezed, and dried overnight at room temperature. Then, the samples were stored in a conditioned laboratory at 20°C and 65% RH at least 24 h before tests.Method 2. PPy was synthetized in presence of poly(styrene sulphate) in order to produce stable water dispersions of PPy nanoparticles. PPy was deposited on fabrics by an ultrasound-assisted deposition process or a spraying coating plant [3].The heating fabrics (PPy amount 27 % wt.), produced with the Method 1, showed excellent electrical properties (voltage: 9 V, electrical current: 108 mA, electrical resistance: 83 ohm, average surface temperature increase: 3.4°C).Antibacterial tests were carried out according to ISO 20743 against Staphylococcus aureus and Escherichia coli on fabrics produced with the Method 2 at different PPy amount. The fabrics with the higher amount of PPy (3.7 % wt.) showed excellent antibacterial properties (~100% of efficacy) against both bacteria.

Polypyrrole is a conjugated polymer that shows excellent electrical conductivity. The electrical conductivity is an intrinsic property of PPy because of its conjugated chemical structure. PPy can be deposited onto textiles (e.g. fibres, yarns, fabrics, non-wovens) by a direct in-situ chemical deposition. PPy-coated textiles have been used for producing heating, EMI shielding and antistatic fabrics, and in developing wearable devices like fibre-shaped dye-sensitized solar cells and sensors.

Cotton gauzes coated with chitosan have been tested as water filter for biological disinfection against Gram-positive bacteria. The present study develops the previous ones, aiming to the stability evaluation of ultraviolet-cured chitosan coating of cotton gauzes in order to optimize the chitosan amount applied to the substrate, lowering the add-on percentage as much as possible: 10%, 5% and 2% wt were here considered. Antibacterial activity and permanence of this property after water flow were tested, showing good results, in particular as regards 10% wt and 5% wt chitosan coated cotton gauze. Moreover, chitosan release was studied in both static and dynamic conditions, with the result that water flux causes a reduction of the amount of chitosan, which remains bounded to the fibres. This reduction depends on the duration of the flux and on the original amount of chitosan on the filter.

Keratin proteins extracted from wool fibers by sulfitolysis were electrospun for the production of active nanofiber membranes (NFMs). The keratin NFMs were composited with nylon woven fabric for improving their mechanical properties as a filtration material. The prepared membranes were characterized in terms of morphology, pore size, contact angle, and performance of water and air permeability. Experimental data showed that most of investigated parameters were affected by the electrospinning time: that is, roughness rose by increasing the electrospinning time, while the narrowest pore size distribution was obtained at the longest electrospinning time (2 h). The pure water permeability (PWP) was greater for the produced NFMs than for the commercial microfiltration membranes and decreased by increasing the electrospinning time. At the longest electrospinning time, the produced NFMs showed a PWP of about 45.7 m3/m2 h bar, which is a value greater than those obtained by conventional materials used in water filtration, including microfiltration membranes. According to the data of contact angle measurements, the high hydrophobicity of NFMs membranes could reinforce their stability in water. Other potential applications could be venting, adsorption of VOCs, and separation of oils from oil/water emulsions.

This chapter deals with the various ways in which keratin (extracted from different sources) can be processed to obtain different types of products. In the first section, solvents and polymers that must be employed tomake this natural biopolymer usable are discussed. Sections 2-5 are mainly oriented in the transformations of keratin in processes such as spinning, electrospinning, casting, foaming, and freezedrying. In addition, some products (fibers, nanofibers, films, coating, and sponge) and applications (filtration, adsorption, and scaffolds) corresponding to the procedures mentioned above are reported. The last section is related to the chemical treatments (e.g., crosslinking) applied to keratin to modify its properties.

Antimicrobial textiles can contribute to the fighting against antibiotic resistance pathogenic microorganisms. Polypyrrole is a conjugated polymer that exerts a biocidal action thanks to positive charges on its backbone chain produced during it synthesis. In this work, dispersions of stable polypyrrole nanoparticles were produced by chemical oxidative polymerization at room temperature in water. An ultrasound-assisted coating process was then used to effectively treat a polyester fabric with the nanoparticles to obtain an optimal antibacterial coating which efficiently eradicates the bacteria. The results showed that the treated fabric with about 4 g/m2 of polypyrrole had log bacteria reductions of 6.0 against Staphylococcus aureus and 7.5 against Escherichia coli. The combination of a polypyrrole synthesis in the form of water nanoparticles dispersions and a continuous coating of fabrics supported by ultrasound overcomes some issues of upscaling of the traditional in-situ chemical deposition used until now for the production of polypyrrole-coated textiles.

Chitosan was deposited on cotton gauze at different add-ons (0.02, 0.05 and 0.10 g chitosan/g cotton) by UV-curing in order to improve its stability in water. Chitosan-cotton gauzes were employed in the adsorption of hexavalent chromium ions, Cr (VI) from aqueous solutions at pH of 3.0 and temperature of 20°C. In this study, kinetic model (Lagergren's pseudo-first-order or Ho's pseudo-second-order) and isotherm adsorption (Langmuir, Freundlich, Dubinin-Radushkevich and BET) were determined. Results showed that the adsorption of chromium occurred by a kinetics of pseudo-second-order with an adsorption isotherm type II. The most probable energy of adsorption, from Dubinin-Radushkevich isotherm model, foresees that a physisorption was achieved by hydrogen bond interactions between chromium ions and protonated amino groups. In addition, the adsorption capacity of chromium ions on grafted chitosan (56 - 103 mg Cr (VI) /g chitosan) was higher than that reported in literature for pure chitosan (8 - 24 mg Cr (VI) /g chitosan). In this way, it was demonstrated that a higher adsorption can be reached with lower amount of chitosan by UV-curing. Finally, the specific surface area occupied by chromium ions was estimated by means of the adsorption capacity of BET model.

Leading companies in the textile sector need objective and precise analytical methodologies able to univocally identify and quantify animal hair fibers present in textile articles, to guarantee that no falsification occurs, especially when cheaper fibers, like wool and yak, are blended with expensive fibers, like cashmere. Traditionally, the methods used for fibers identification are: light microscopy, that gives information on the internal and external structure of the fibers, reveals details of the shape, cuticle morphology, internal pigmentation and medullation; and scanning electron microscopy (SEM) that shows the fine structure of the cuticle cells at high resolution. Anyway, these methodologies are subjective, depending on the expertise of the operator, and often are affected by chemical treatments to which the fibers have been submitted during textile processing. Several methods have been developed in the past to remedy these problems, with poor results. CNR-ISMAC of Biella in collaboration with the Department of Food and Drug of the University of Parma developed a new method for qualitative and quantitative analysis of animal hair fibers. The method based on electrospray (ESI) mass spectrometry (MS) combined with liquid chromatography (LC) follows a proteomic approach to assess molecular markers for species identification [1-3]. In particular, the method focuses on the identification and quantification of wool, cashmere and yak fibers. Keratin from sheep, cashmere goat and yak are similar but not identical, because in some specific parts there are amino acidic variants resulting in specific peptide-markers which can be used to distinguish each animal fiber. The procedure includes an enzymatic digestion of the keratin after the protein extraction in order to obtain similar but not identical homologous peptides, which can be discriminated by LC/ESI-MS analysis. These markers have been successfully used not only for qualitative analysis of wool, cashmere and yak blends, but also for quantitative ones, with a limit of detection of 3%. Recently, this proteomic method has become international standard: "ISO 20418-1 Textiles - Qualitative and quantitative proteomic analysis of some animal hair fibres Part 1: Peptide detection using LC-ESI-MS with protein reduction". The standard method will be also adopted by CEN (European Committee for Standardization) and UNI (Ente Nazionale Italiano di Unificazione) soon. In the meantime, ISMAC Biella is continuing its research to verify the applicability of the proteomic method also to the South American camelids (lama, alpaca, vicuna and guanaco) and camel hairs, so that in the future it will be possible to extend the standard to these fibers as well.

Electrospinning is a simple method to produce nanofibers with high specific surface. Keratin is a biocompatible and biodegradable protein extracted from wool, which can be electrospun pure or in blend with other polymers, such as polyamide. It supports fibroblasts and osteoblasts growth. Moreover, nanofiber-based filters can remove small-sized particles and keratin nanofibers can absorb heavy metals and dyes from water, and VOCs from air. In biomedical applications, pure keratin nanofibers was applied as bio-finishing to functionalize titanium surfaces of dental implants. The aim is the improvement of soft tissue adhesion avoiding epithelial down-growth and bacterial infiltration on the collar. Keratin nanofibers were found to greatly improve fibroblast cells growth already at 24h. In bone regeneration, nano-hydroxyapatite (HAp) was used in composite electrospun keratin-based nanofibers. Water was used as solvent to produce HAp/keratin-based composite nanofibers. The nanofibers have been tested for osteoblasts cells growth, showing biocompatibility by cell viability assay. Moreover, antibacterial keratin-based nanofibers were produced by the addition of a protein-complex containing Irgasan, as a model biocide. The material has a slow release with a very high antibacterial activity after 24 h. Air pollution and water contamination are severe environmental issues. The discharge of polluting wastewater harms the aquatic life, adversely affects human health and limits water resources. New water filtration systems based on electrospun nanofibers have been proposed. In addition, composite nanofibers embedding functional nanoparticles (i.e. TiO2, silver) allow the depuration of water from pollutant compounds and bacteria.

The general definition of sustainable economy is the ability of an economy to maintain defined levels of economic production indefinitely. This theme is closely linked to the introduction of environmental friendly processes, to the study of new materials obtainable from renewable sources and to the exploitation and minimization of by-products and wastes from industrial processes. The biorefinery concept match all these aspects: in a biorefinery biomass conversion processes are integrated and value-added chemicals, new materials, fuels, power, heat, can be obtained in a sustainable way with environmental friendly processes. For this purpose the employ of enzymes play a key role in biorefineries because they constitute an important alternative to the traditional and environmental impact chemical compounds and processes [1]. An interesting example is the case of Thailand, where agriculture and textile industry are working together to exploit the resources obtainable from pineapple cultivation [2]. This nation produce over 2.2 million t/y of pineapple fruits; connected to this cultivation, recently, is developing a new business resulting from the extraction of fibers from pineapple leaves (PALF), to be employed in the textile sector. These fibers are obtained from the leaves of the plant Ananas Comosus, which belongs to the Bromeliaceae family; they contain fibers (2.5 ÷ 3.5 %), pentosans (17.8 %), lignin (4.2 ÷ 12 %), fat and wax (3.3 %) and pectins (1.1 %) [3]. The presence of other constituents than fibers constitute an impurity that needs be removed, in particular lignin that act as a glue for the fibrillar structure of the fibers, is responsible of the non-wettability and consequently of the non-dyeing of the fibers. This fiber is silky, fine and has interesting textile properties, is capable of blending with jute, cotton, ramie and some other synthetic fibres: so it can capture an important position among natural fibers as potential commercial grade textile fiber [4]. In consideration of its properties, PALF is placed between jute and cotton or jute and ramie. This work propose the development of an industrial process for extraction of fibres and exploitation of other constituents, in order to reach a sustainable and economical profitable production process.

Polypyrrole is widely used as coating to produce electrically conductive textiles. Counter-ions (i.e. doping agents) were embedded in polypyrrole to improve electrical conductivity. Good electrical performances are required for several applications, such as microwave attenuation/electro-magnetic interference shielding, heat generation, electro-static discharge protection, sensing, and energy storage. In this work, a systematic study was carried out on the effects of doping agents in coating cotton fabrics with a thin polypyrrole layer. A total of 11 compounds were selected and compared as counter-ions. The electrical performances of the coated fabrics were assessed with measures of electrical conductivity. Moreover, evenness and morphology of the resulting polypyrrole layer were discussed. As the final result, the best performances in terms of electrical conductivity (i.e. low surface resistivity) were measured using on dicyclohexyl sulfosuccinate, 2,6-naphthalenedisulfonate or 1,5-naphthalenedisulfonate as doping agents. The weight increases after polypyrrole deposition on the fabrics were greater than 15% and polypyrrole deposited on the fibers as a uniform film. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42831.

In this study, we aimed to examine to study the effects of heating treatments on wool-derived keratin nanofibers obtained by electrospinning. Interestingly, the keratin nanofibers did not lose their nanofibrous shape at high temperatures. On the contrary, the diameter of keratin nanofibers significantly decreased after heating. Even the chemical structure of the keratin was not significantly altered by heating, as observed by IR spectroscopy, except for a shoulder at 1720 cm−1 and the amide III band. The spectral feature changes matched the formation of crosslinking amide bonds between protein chains well. Moreover, for various applications, it is essential that nanofibers are stable in water. Heating treatments were carried out at different temperatures and times to assess what heating conditions gave the keratin nanofibers water stability. Finally, no significant changes in the thermal behavior were observed in the samples after heating treatments compared to the untreated keratin nanofibers; this was a sign of negligible or slight degradations of the protein chains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40532.

Electrospinning is here used for the first time to prepare nanofibers including a host/guest complex in a keratin/poly(ethylene oxide) matrix. The host is a lipid binding protein and the guest is an insoluble bactericidal molecule, irgasan, bound within the protein internal cavity. The obtained nanofibers, characterized by scanning electron microscopy, exhibit excellent antibacterial activity toward Gram positive and negative bacteria, even with a moderate protein/irgasan cargo. Solution NMR studies, employed to provide molecular information on the cargo system, points to a micromolar affinity, compatible with both the electrospinning process and slow guest release. The versatility of the carrier protein, capable of interacting with a variety of druggable hydrophobic molecules, is exploitable for the development of innovative biomedical devices, whose properties can be tuned by the selected guest.

Few polymers with practical and technological appeal can be electrospun into nanofibers from water solutions. The production of polymer nanofibers from water solution is considered green, up-scalable and versatile. From this point of view, the use of nanoparticles in the form of water colloidal suspension instead of nano-powder should be more affordable and safer. The combination of these two aspects makes a breakthrough in materials science on electrospun nanomaterials. In this work, multi-component organic/inorganic nanofibers were produced by electrospinning water solutions of a protein extracted from wool (i.e. keratin) containing nanosols of titanium dioxide and metal silver. In order to improve electrospinnability, poly(ethylene oxide) was added to the solutions. Colloidal stability was studied in depth to preserve nanoparticle dimension as smaller as possible in the electrospinning solutions. Resulting hybrid keratin-based nanofibers were made water insoluble by treatments at high temperature, expanding the range of applications of such a nanomaterial. In this way, it was also possible to wash out poly(ethylene oxide) from nanofibers maintaining a nanofibrous structure and small-sized porosity comparable to the as-spun materials. Finally, the functional properties of electrospun hybrid nanofibers were evaluated. Both antibacterial and photo-catalytic activities of titanium dioxide nanoparticles embedded into the nanofibers were quantified, as well as antibacterial property of nano-silver. The results demonstrate that nanoparticle functionalities were maintained in electrospun keratin nanofibers.