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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.

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.

Peri-implantitis is a severe condition affecting the success of transmucosal dental implants: tissue healing is severely limited by the inflammatory processes that come about to control homeostasis in the surrounding tissues. The main cause of peri-implantitis is bacterial biofilm infection; gingival fibroblasts play a pivotal role in regulating the inflammatory cascades. A new technology aimed at preventing bacterial colonization of titanium (Ti) implants, and enhancing the spread of gingival fibroblasts, is presented. Using electro-spinning, mirror-polished Ti disks were uniformly coated with keratin fibers obtained from discarded wool via sulfitolysis. The keratin-coated surfaces were then doped with silver (Ag) to introduce antibacterial properties, using different concentrations of silver nitrate as a precursor (0.01, 0.05 and 0.1 M). The resulting specimens were characterized in terms of morphology and chemical composition by FESEM, FTIR and XPS, revealing silver concentrations between 1.7 and 1.9%. Silver release into the medium was evaluated in the presence of cells (a-MEM) or bacteria (LB) by ICP; release was 0.2-1.4 mg l1 for a-MEM, and 10-40 mg l1 for LB. The antibacterial properties of the Ag-doped specimens were tested against a multidrug-resistant Staphylococcus aureus biofilm through morphology (FESEM) and metabolic assay (XTT); reduction in viability was significant (p o 0.05; 480% reduction within 72 h). Lastly, the cytocompatibility of the specimens was confirmed using human primary gingival fibroblasts, whose viability, spread and matrix deposition were found to be comparable to those of untreated Ti polished controls (p 4 0.05). Thus, Ag surface enrichment was effective in reducing viability and maturation of S. aureus biofilm, without compromising human cell viability. Moreover, cell spread was found to be very sensitive to keratin fiber stimulation. The strategy thus appears to be very promising to introduce surface features in line with the main requirements for transmucosal dental implants.

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.

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.

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.

Periimplantitis and epithelial downgrowth are two of the main conditions related to dental implants failure. In transmucosal implants, bacterial infection is due to bacterial penetration through the soft tissues in contact with the implant and biofilm formation on the implant surface. The defect in soft tissue sealing and the apically epithelial downgrowth till to the bone level are responsible of bone resorption and implant mobilization promoted by inflammation of the connective tissue. Gingival fibroblasts play an important role in periimplantitis because they are the promoters of the inflammatory process. Moreover, the related inflammatory state is commonly driven also to counteract bacteria implants colonization. In the present work, a new technology for soft tissue contact is proposed. The first focus of this research was to promote and drive gingival fibroblasts adhesion, proliferation and orientation on commercially pure titanium surfaces by means of mechanically produced nanogrooves (0.1-0.2 ?m) and keratin nanofibers deposited by electrospinning. 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) 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. The second aim of this research was to introduce antibacterial properties to the developed technology. So, mirror-polished keratin-coated surfaces were doped with silver (Ag) using different concentrations of silver nitrate as a precursor. The antibacterial properties of the Ag-doped specimens were tested against a multidrug-resistant Staphylococcus aureus biofilm through morphology (FESEM) and metabolic assay (XTT); reduction in viability was significant (480% reduction within 72 h). Lastly, the cytocompatibility of the specimens was confirmed using human primary gingival fibroblasts, whose viability, spread and matrix deposition were found to be comparable to those of untreated Ti polished controls. Thus, Ag surface enrichment was effective in reducing viability and maturation of S. aureus biofilm, without compromising human cell viability. The strategy thus appears to be very promising to introduce surface features in line with the main requirements for transmucosal dental implants.

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.