Recycling of textile wastes, by acid hydrolysis, into new cellulosic raw materials.

Chemical recycling can be used to separate fibers that are constituents of different types of fabrics. This type of process can be considered one of the most effective forms of recycling, given that a large part of fabrics is made up of fiber mixtures. As part of an innovative circular strategy, the main goal of this work was to study the conditions for extracting cellulose from mixed textile wastes by acid hydrolysis and further transform it into cellulose derivatives, thus contributing to reduce such wastes and expanding the possible sources of cellulose. Our work covers a wide range of textile wastes and addresses the main technical challenges of this recycling methodology. The percentage of recovered cellulose powder varies between 65 and 88%. To evaluate the feasibility of using the extracted cellulose as raw material to produce cellulose derivatives, two strategies were applied: etherification to obtain sodium carboxymethylcellulose (with degree of substituion between 0.27 and 0.61) and esterification, to obtain cellulose acetate (with degree of substituion of 2.59). The cellulose derivatives obtained are very useful as additives in the textile industry, and hence the concept and practice of a circular economy are promoted.

Safety Assessment of Polypyrrole Nanoparticles and Spray-Coated Textiles.

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.

Trends on the Cellulose-Based Textiles: Raw Materials and Technologies.

There is an emerging environmental awareness and social concern regarding the environmental impact of the textile industry, highlighting the growing need for developing green and sustainable approaches throughout this industry's supply chain. Upstream, due to population growth and the rise in consumption of textile fibers, new sustainable raw materials and processes must be found. Cellulose presents unique structural features, being the most important and available renewable resource for textiles. The physical and chemical modification reactions yielding fibers are of high commercial importance today. Recently developed technologies allow the production of filaments with the strongest tensile performance without dissolution or any other harmful and complex chemical processes. Fibers without solvents are thus on the verge of commercialization. In this review, the technologies for the production of cellulose-based textiles, their surface modification and the recent trends on sustainable cellulose sources, such as bacterial nanocellulose, are discussed. The life cycle assessment of several cellulose fiber production methods is also discussed.

Proteins Derived from the Dairy Losses and By-Products as Raw Materials for Non-Food Applications.

The disposal of a high volume of waste-containing proteins is becoming increasingly challenging in a society that is aware of what is happening in the environment. The dairy industry generates several by-products that contain vast amounts of compounds, including proteins that are of industrial importance and for which new uses are being sought. This article provides a comprehensive review of the potential of the valorisation of proteins that can be recovered by chemical and/or physical processes from protein-containing milk by-products or milk surplus, particularly whey proteins or caseins. Whey proteins and casein characteristics, and applications in non-food industries, with special emphasis on the textile industry, packaging and biomedical, are reported in this review, in order to provide knowledge and raise awareness of the sustainability of these proteins to potentiate new opportunities in a circular economy context.

Exploring the potential of polyethylene terephthalate in the design of antibacterial surfaces.

Polyethylene terephthalate (PET) is one of the most used polymeric materials in the health care sector mainly due to its advantages that include biocompatibility, high uniformity, mechanical strength and resistance against chemicals and/or abrasion. However, avoiding bacterial contamination on PET is still an unsolved challenge and two main strategies are being explored to overcome this drawback: the anti-adhesive and biocidal modification of PET surface. While bacterial adhesion depends on several surface properties namely surface charge and energy, hydrophilicity and surface roughness, a biocidal effect can be obtained by antimicrobial compounds attached to the surface to inhibit the growth of bacteria (bacteriostatic) or kill bacteria (bactericidal). Therefore, it is well known that granting antibacterial properties to PET surface would be beneficial in the prevention of infectious diseases. Different modification methods have been reported for such purpose. This review addresses some of the strategies that have been attempted to prevent or reduce the bacterial contamination on PET surfaces, including functionalisation, grafting, topographical surface modification and coating. Those strategies, particularly the grafting method seems to be very promising for healthcare applications to prevent infectious diseases and the emergence of bacteria resistance.

Design of a chromogenic substrate for elastase based on split GFP system-Proof of concept for colour switch sensors.

Recent studies have demonstrated that human neutrophil elastase (HNE) can be used as marker for inflammation/infection of chronic wounds since it was found to be present in high concentration in exudate collected from chronic wounds. Biosensors used in wound care benefit from a chromogenic signalling due to the readiness of signal interpretation, but the most common use faint yellow chromogenic molecules such as p-nitroaniline (pNa). In addition, if to be converted into smart dressings, the colour of the detection system should not be masked by the exudate's colour. In this work, we designed a chromogenic substrate for HNE aiming to be incorporated in a smart dressing as a colour switch sensor. The substrate was developed using the GFP-like chromoprotein ultramarine (UM), following the split GFP technology. The cleavage sequence for HNE (Ala-Ala-Pro-Val) was embedded into the sensing moiety of the substrate corresponding to the 11th ß-sheet. In the presence of HNE, the 11th ß-sheet is able to interact to the signalling moiety composed of the ß1-ß10 incomplete barrel, allowing the re-establishment of the chromophore environment and, hence, the colour production. Structural homology and molecular dynamics simulations were conducted to aid on the disclosure of the structural changes that are the base of the mechanism of action of this HNE switch substrate. Our findings explore the possible application of GFP-like chromogenic sensors in point-of-care devices for the evaluation of the wounds status, representing a major step in the medical field.

Internalization of Methotrexate Conjugates by Folate Receptor-α.

The folate antagonist methotrexate is a cytotoxic drug used in the treatment of several cancer types. The entry of methotrexate into the cell is mediated by two main transport systems: the reduced folate carrier and membrane-associated folate receptors. These transporters differ considerably in their mechanism of (anti)folate uptake, substrate specificity, and tissue specificity. Although the mechanism of action of the reduced folate carrier is fairly well-established, that of the folate receptor has remained unknown. The development of specific folate receptor-targeted antifolates would be accelerated if additional mechanistic data were to become available. In this work, we used two fluorescently labeled conjugates of methotrexate, differently linked at the terminal groups, to clarify the uptake mechanism by folate receptor-α. The results demonstrate the importance of methotrexate amino groups in the interaction with folate receptor-α.

Two Engineered OBPs with opposite temperature-dependent affinities towards 1-aminoanthracene.

Engineered odorant-binding proteins (OBPs) display tunable binding affinities triggered by temperature alterations. We designed and produced two engineered proteins based on OBP-I sequence: truncated OBP (tOBP) and OBP::GQ20::SP-DS3. The binding affinity of 1-aminoanthracene (1-AMA) to these proteins revealed that tOBP presents higher affinity at 25 °C (kd = 0.45 µM) than at 37 °C (kd = 1.72 µM). OBP::GQ20::SP-DS3 showed an opposite behavior, revealing higher affinity at 37 °C (kd = 0.58 µM) than at 25 °C (kd = 1.17 µM). We set-up a system containing both proteins to evaluate their temperature-dependent binding. Our data proved the 1-AMA differential and reversible affinity towards OBPs, triggered by temperature changes. The variations of the binding pocket size with temperature, confirmed by molecular modelling studies, were determinant for the differential binding of the engineered OBPs. Herein we described for the first time a competitive temperature-dependent mechanism for this class of proteins.

Oil-based cyclo-oligosaccharide nanodevices for drug encapsulation.

New encapsulation nanodevices were synthesized by emulsification of cyclo-oligosaccharides fully substituted by hydrophobic palmitic chains. These highly hydrophobic compounds, acquire oily-like behaviour at moderate temperatures (∼50°C) and when submitted to ultrasound (US) can undergo emulsification. The improved emulsifying properties of modified cyclo-oligosaccharides are suitable to produce small and narrow sized nanoemulsions with ability to encapsulate amphiphilic molecules. Both encapsulation and delivery of a therapeutic drug, methotrexate (MTX), with amphiphilic character was assessed. The physicochemical properties of the cyclo-oligosaccharide nanoemulsions containing MTX were investigated by nuclear magnetic resonance (NMR), scanning transmission electron microscopy (STEM) and dynamic light scattering (DLS). The results revealed that the modified cyclo-oligosaccharides are potential platforms for the encapsulation of bio compounds for cosmetic and pharmaceutical purposes.

Peptide-protein interactions within human hair keratins.

We selected 1235 decapeptides from human hair proteins encoded by human genes of keratins and keratin associated proteins. The peptides were linked to glass arrays and screened for their affinity towards a solution of human hair extracted keratin fraction. Based on the physicochemical properties of the peptides, ten variables were studied: content of different types of amino acid side chains (cysteine, hydrophobic, polar, basic, acidic, aromatic rings, amide, alcohol side chains), isoelectric point, and net charge. We found differences statistically significant on the binding affinity of peptides based on their content of cysteine, hydrophobic and polar amino acids, mainly containing alcohols. These results point to the formation of hydrophobic interactions and disulfide bonds between small peptides and human hair keratins as the main driving forces for the interaction of possible cosmetic peptides, namely designed to strength human hair. As so, our results enlighten the nature of the interaction of keratin based materials with human hair, which are claimed to enhance hair fiber strength, and enable a more directed and sustained hair care peptide design.

Permeation of skin with (C60) fullerene dispersions.

Dispersions in transcutol/isopropyl myristate make C60 fullerene molecules suitable for transdermal delivery. We found that C60 can successfully permeate the skin using pig skin in Franz diffusion cells. Molecular dynamics simulations and transmission electron microscopy confirmed these observations. Basic cosmetic formulations with transcutol/isopropyl myristate without harsh organic solvents show a high potential for delivery of C60 for biopharmaceutical and cosmetics applications.

In vivo confocal Raman spectroscopy and molecular dynamics analysis of penetration of retinyl acetate into stratum corneum.

OBJECTIVE: The purpose of this study is to elucidate the behavior of retinyl acetate in penetrating human skin without the presence of enhancers by using confocal Raman spectroscopy and molecular dynamics simulation. METHODS: In this study, in vivo confocal Raman spectroscopy was combined with molecular dynamics simulation to investigate the transdermal permeation of the aqueous suspension of retinyl acetate. RESULTS: Permeation was measured after 30min, and retinyl acetate was found up to 20µm deep inside the stratum corneum. The delivery of retinyl acetate inside a skin membrane model was studied by molecular dynamics. The membrane model that was used represented normal young skin containing a lipid bilayer with 25% ceramide, 36% fatty acid, 30% cholesterol, and 6% cholesterol sulfate. CONCLUSION: Spectroscopy data indicate that retinyl acetate permeates into the stratum corneum. Molecular dynamics data showed that retinyl acetate permeates in the membrane model and that their final location is deep inside the lipid bilayer. We showed, for the first time, a correlation between Raman permeation data and computational data.

Insights on the mechanical behavior of keratin fibrils.

A computational molecular model of a truncated keratin protofibril (8 chains of hair keratin, PDB provided in Supplementary material) was used, to run a series of steered molecular dynamics simulations obtaining strain-stress curves. These results were compared with experimental mechanical data on hair fibers. Our data demonstrate that the molecular dynamics simulations can model hair mechanical properties. Simulations done in vacuum showed a better agreement with experimental Young's Modulus (YM) values. The role of hydrogen bonds and the secondary structure of keratin on the mechanical properties was evaluated in detail. The incubation with a fragment of one surfactant protein, the SPD-2 peptide (QAAFSQ), showed the improvement of YM of the hair keratin either by simulations and experimental data. For the first, our research provides mechanistic insights on mechanical microscopic properties of keratin protofibrils through molecular dynamics simulations.

Protein Formulations for Emulsions and Solid-in-Oil Dispersions.

Needs from medical and cosmetic areas have led to the design of novel nanosized emulsions and solid-in-oil dispersions of proteins. Here, we describe the production of those emulsions and dispersions using high-energy methodologies such as high-pressure homogenization or ultrasound. Recent work has resulted in new mechanistic insights related to the formation of protein emulsions and dispersions. The production method and composition of these formulations can determine major parameters such as size, stability, and functionality, and therefore their final application. Aqueous nanoemulsions of proteins can be used for drug delivery, while solid-in-oil dispersions are often used in transdermal applications.

Albumin-Based Nanodevices as Drug Carriers.

Nanomedicine, the application of nanotechnology to medicine, is being increasingly used to improve and exploit the advantages of efficient drug delivery. Different nanodevices have been developed in recent years, among them protein-based nanoparticles which have gained considerable interest. Albumin is a versatile protein carrier with several characteristics that make it an ideal candidate for drug delivery, such as its availability, its biocompatibility, its biodegradability, and its lack of toxicity and immunogenicity. This review embodies an overview of different methods available for production of albumin-based nanoparticles, with focus on high-energy emulsification methods. A comparison between production by using sonication, which involves acoustic cavitation, and the high pressure homogenization method, where occurs hydrodynamic cavitation, is presented. Taking into account important properties of nanoparticles required for intravenous administration, the use of poloxamers, tri-block copolymer surfactants is discussed as it improves blood circulation time and bioavailability of nanoparticles. Thus, nanoparticles can be engineered to provide adequate features to therapeutic applications, in which can be included surface functionalization with targeting agents. Different albumin-based formulations and their therapeutic applications are presented in this review, with emphasis on applications in cancer therapy, where albumin-based strategies are promising for targeted drug delivery in innovative clinical strategies.

Assessment of a Protease Inhibitor Peptide for Anti-Ageing.

Ageing and skin exposure to UV radiation induces production and activation of matrix metalloproteinases (MMPs) and human neutrophil elastase (HNE). These enzymes are known to break down the extracellular matrix (ECM) which leads to wrinkle formation. Here, we demonstrated the potential of a solid-in-oil nanodispersion containing a competitive inhibitor peptide of HNE mixed with hyaluronic acid (HA), displaying 158 nm of mean diameter, to protect the skin against the ageing effects. Western blot analysis demonstrated that activation of MMP-1 in fibroblasts by HNE treatment is inhibited by the solid-in-oil nanodispersion containing the peptide and HA. The results clearly demonstrate that solid-in-oil nanodispersion containing the HNE inhibitor peptide is a promising strategy for anti-ageing effects. This effect can be seen particularly by ECM regulation by affecting fibroblasts. The formulation also enhances the formation of thicker bundles of actin filaments.

Peptide Anchor for Folate-Targeted Liposomal Delivery.

Specific folate receptors are abundantly overexpressed in chronically activated macrophages and in most cancer cells. Directed folate receptor targeting using liposomes is usually achieved using folate linked to a phospholipid or cholesterol anchor. This link is formed using a large spacer like polyethylene glycol. Here, we report an innovative strategy for targeted liposome delivery that uses a hydrophobic fragment of surfactant protein D linked to folate. Our proposed spacer is a small 4 amino acid residue linker. The peptide conjugate inserts deeply into the lipid bilayer without affecting liposomal integrity, with high stability and specificity. To compare the drug delivery potential of both liposomal targeting systems, we encapsulated the nuclear dye Hoechst 34580. The eventual increase in blue fluorescence would only be detectable upon liposome disruption, leading to specific binding of this dye to DNA. Our delivery system was proven to be more efficient (2-fold) in Caco-2 cells than classic systems where the folate moiety is linked to liposomes by polyethylene glycol.

Size controlled protein nanoemulsions for active targeting of folate receptor positive cells.

Bovine serum albumin (BSA) nanoemulsions were produced by high pressure homogenization with a tri-block copolymer (Poloxamer 407), which presents a central hydrophobic chain of polyoxypropylene (PPO) and two identical lateral hydrophilic chains of polyethylene glycol (PEG). We observed a linear correlation between tri-block copolymer concentration and size - the use of 5mg/mL of Poloxamer 407 yields nanoemulsions smaller than 100nm. Molecular dynamics and fluorescent tagging of the tri-block copolymer highlight their mechanistic role on the size of emulsions. This novel method enables the fabrication of highly stable albumin emulsions in the nano-size range, highly desirable for controlled drug delivery. Folic Acid (FA)-tagged protein nanoemulsions were shown to promote specific folate receptor (FR)-mediated targeting in FR positive cells. The novel strategy presented here enables the construction of size controlled, functionalized protein-based nanoemulsions with excellent characteristics for active targeting in cancer therapy.

Design of novel BSA/hyaluronic acid nanodispersions for transdermal pharma purposes.

A novel transdermal hyaluronic acid (HA) conjugated with bovine serum albumin (BSA) was developed in the form of solid-in-oil (S/O) nanodispersion (129.7 nm mean diameter). Ex vivo skin penetration analysis by fluorescence and confocal observation of histological skin sections revealed the ability of BSA/HA nanodispersions to cross the stratum corneum and penetrate into the dermis. Furthermore, no significant toxicity was found in fibroblast and keratinocyte cells in vitro. These results proved the potential of the developed nanodispersion for transdermal delivery of hyaluronic acid constituting a high value to biopharmaceutical and cosmetics industries.

Odorant binding proteins: a biotechnological tool for odour control.

The application of an odorant binding protein for odour control and fragrance delayed release from a textile surface was first explored in this work. Pig OBP-1 gene was cloned and expressed in Escherichia coli, and the purified protein was biochemically characterized. The IC50 values (concentrations of competitor that caused a decay of fluorescence to half-maximal intensity) were determined for four distinct fragrances, namely, citronellol, benzyl benzoate, citronellyl valerate and ethyl valerate. The results showed a strong binding of citronellyl valerate, citronellol and benzyl benzoate to the recombinant protein, while ethyl valerate displayed weaker binding. Cationized cotton substrates were coated with porcine odorant binding protein and tested for their capacity to retain citronellol and to mask the smell of cigarette smoke. The immobilized protein delayed the release of citronellol when compared to the untreated cotton. According to a blind evaluation of 30 assessors, the smell of cigarette smoke, trapped onto the fabrics' surface, was successfully attenuated by porcine odorant binding protein (more than 60 % identified the weakest smell intensity after protein exposure compared to ß-cyclodextrin-treated and untreated cotton fabrics). This work demonstrated that porcine odorant binding protein can be an efficient solution to prevent and/or remove unpleasant odours trapped on the large surface of textiles. Its intrinsic properties make odorant binding proteins excellent candidates for controlled release systems which constitute a new application for this class of proteins.