Polydopamine-modified interface improves the immobilization of natural bioactive-dye onto textile and enhances antifungal activity.

Dermatomycosis, such as candidiasis and mycosis among others, has emerged recently as the most frequent fungal infection worldwide. This disease is due to the skin's exposure to microorganisms that are able to pass through skin barrier defects. Therefore, textiles in direct contact with skin can serve as a source of contamination and fungus spread. In the current study, a sustainable and eco-friendly method for antifungal cotton finishing using Curcuma longa L extracted from rhizomes was investigated. To enhance the natural bioactive dye uptake and attachment, cellulosic cotton fibers were chemically modified using dopamine, a biocompatible molecule, leading to the deposition of a hydrophilic layer of polydopamine. The efficiency of the polydopamine coating on the cotton surface has been assessed by x-ray photoemission spectroscopy analyses, with the detection of nitrogen, and by water contact angle for the wettability enhancement. Furthermore, characterization of the modified samples confirms that the modification did not affect either the cellulosic fiber morphology or the mechanical properties. The dyeability and bioactive dye immobilization were then assessed by colorimetry. Finally, the effectiveness of the finished fabrics against Trichophyton (rubrum/mentagrophytes) and Candida albicans strains was evaluated and was shown to induce growth inhibition mainly on Candida albicans strains.

Effect of electrolyte composition and deposition current for Fe/Fe-P electroformed bilayers for biodegradable metallic medical applications.

With its proven biocompatibility and excellent mechanical properties, iron is an excellent source material for clinical cardiac and vascular applications. However, its relatively low degradation rate limits its use for the healing and remodeling of diseased blood vessels. To address these issues, a multi-purpose fabrication process to develop a bilayer alloy composed of electroformed iron (E-Fe) and iron-phosphorus (Fe-P) was employed. Bilayers of Fe/Fe-P were produced in an electrolytic bath. The effects of electrolyte chemical composition and deposition current density (idep) on layer structure and chemical composition were assessed by scanning electron microscopy, electron probe microanalysis, X-ray diffraction and X-ray photoelectron spectroscopy. The corrosion rate was determined by potentiodynamic polarization tests. The bilayers showed an increasing amount of P with increasing NaH2PO4·H2O in the electrolyte. Fe-P structure became finer for higher P amounts. Potentiodynamic polarization tests revealed that the corrosion rate was strongly influenced by deposition conditions. For a P amount of ~2 wt.%, the corrosion rate was 1.46mm/year, which confirms the potential of this material to demonstrate high mechanical properties and a suitable corrosion rate for biomedical applications.

A comparison of adsorbed and grafted fibronectin coatings under static and dynamic conditions.

Coatings for medical devices are expected to improve their surface biocompatibility mainly by being bioactive, i.e. stimulating healing-oriented interactions with living cells, tissues and organs. In particular, for stent applications, coatings are often designed to enhance the endothelialization process. The coating strategy will be primarily responsible for the interfacial properties between the substrate and the coating, which must show high stability. Therefore, the present work aims at comparing the stability of adsorbed and grafted fibronectin, a protein well-known to promote endothelialization. Fibronectin coatings were deposited on fluorocarbon films generated by a plasma-based process on stainless steel substrates. Then, deformation tests were performed in order to simulate the stenting procedure and stability tests were completed under static and under-flow conditions. Coatings were characterized by XPS, AFM, water contact angle, immunostaining and ToF-SIMS analyses. The results show higher stability for the grafted coatings; indeed, the integrity of the protein simply adsorbed was strongly compromised especially after under-flow tests. Both coatings exhibited similar behavior after deformation and static tests. These results clearly show the impact of the coating strategy on the overall stability of the coatings as well as the importance of under-flow investigations.

The use of multiple pseudo-physiological solutions to simulate the degradation behavior of pure iron as a metallic resorbable implant: a surface-characterization study.

Understanding the interactions of a pure iron surface with biological elements, such as ions and proteins in an aqueous medium, is essential for an accurate in vitro assessment of corrosion patterns. In fact, the synergy of chlorides, carbonates, phosphates and complex organic molecules present in the body environment is a key factor affecting both in vivo and in vitro degradation of materials, especially iron and its alloys. The aim of this work was the assessment of degradation patterns of pure iron in 5 commercial pseudo-physiological solutions by a thorough study of degraded surface chemistry and morphology. It also provides a methodological basis to understand the short-term degradation mechanism of degradable iron depending on the surrounding physiological media. The standard static immersion corrosion test was modified to adapt the procedure to pseudo-physiological solutions. After a 14-day static immersion test, the surfaces of samples were investigated by scanning electron microscopy, stylus profilometry and atomic force microscopy techniques. The chemistry and phase composition of the degraded layers were evaluated, respectively, by X-ray photoelectron spectrometry and X-ray diffractometry. The morphology and composition of the degradation layers were found to be different for the test-solutions: for phosphate-rich solutions, the formation of an adherent passive layer was found; degradation mechanisms related to general corrosion were predominant for all the other solutions. In conclusion, the chemical composition of the used medium plays a fundamental role in the degradation pattern of pure iron, so that direct comparisons of solutions with different ion concentrations, as reported in the literature, need to be carefully assessed.

Enhancing the functionality of cotton fabric by physical and chemical pre-treatments: A comparative study.

Recently, antimicrobial and decontaminating textiles, such as cotton a natural carbohydrate polymer, are generating more attention. Plant materials used for natural dyes are expected to impart biofunctional properties and high added valued functional textiles. In the current study, surface modification of cotton to maximize the dye amount on the surface has been investigated. Physical modification using nitrogen-hydrogen plasma, chemical modification using chitosan and chemical modification using dopamine as biopolymers imparting amino groups were explored. Furthermore, dye exhaustion of curcumin, as a natural functional dye has been studied. Dye stability tests were also performed after fabric washing using hospital washing protocol to predict the durability of the functionalizations. The results demonstrated that cotton surfaces treated with dopamine exhibit a high level of dye uptake (78%) and a good washing fastness. The use of non-toxic and natural additives during cotton finishing process could give the opportunity of cradle to cradle design for antimicrobial textile industries.

In vitro degradation behavior of Fe-20 Mn-1.2C alloy in three different pseudo-physiological solutions.

High manganese austenitic steels such as Fe-20Mn-1.2C alloys are among the most promising candidates for biodegradable stents applications due to their high strength, high ductility and their chemical composition. In the current work, 14 day static in-vitro tests were performed in controlled atmosphere to assess the degradation behavior in three common pseudo-physiological solutions, i.e. commercial Hanks' (CH), modified Hanks' (MH) and albumin-enriched Dulbecco's modified phosphate buffered saline (DPBS) solutions. The degraded samples surfaces as well as the degradation products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Degradation of material and degradation products are shown to be strongly dependent on the test medium due to the presence of different ionic species such as HCO3(-), CO3(2-), Cl(-), Ca(2+) or phosphate groups. In both MH and CH solutions, the increased content of HCO3(-) ions seems to promote MnCO3 crystal growth on sample surfaces whereas the presence of albumin and high content of phosphate ions promotes the formation of an amorphous layer rich in phosphates, iron and manganese.

Effect of grain sizes on mechanical properties and biodegradation behavior of pure iron for cardiovascular stent application.

Pure iron has been demonstrated as a potential candidate for biodegradable metal stents due to its appropriate biocompatibility, suitable mechanical properties and uniform biodegradation behavior. The competing parameters that control the safety and the performance of BMS include proper strength-ductility combination, biocompatibility along with matching rate of corrosion with healing rate of arteries. Being a micrometre-scale biomedical device, the mentioned variables have been found to be governed by the average grain size of the bulk material. Thermo-mechanical processing techniques of the cold rolling and annealing were used to grain-refine the pure iron. Pure Fe samples were unidirectionally cold rolled and then isochronally annealed at different temperatures with the intention of inducing different ranges of grain size. The effect of thermo-mechanical treatment on mechanical properties and corrosion rates of the samples were investigated, correspondingly. Mechanical properties of pure Fe samples improved significantly with decrease in grain size while the corrosion rate decreased marginally with decrease in the average grain sizes. These findings could lead to the optimization of the properties to attain an adequate biodegradation-strength-ductility balance.

Influence of cross-rolling on the micro-texture and biodegradation of pure iron as biodegradable material for medical implants.

Iron-based biodegradable metals have been shown to present high potential in cardiac, vascular, orthopaedic and dental in adults, as well as paediatric, applications. These require suitable mechanical properties, adequate biocompatibility while guaranteeing a low toxicity of degradation products. For example, in cardiac applications, stents need to be made by homogeneous and isotropic materials in order to prevent sudden failures which would impair the deployment site. Besides, the presence of precipitates and pores, chemical inhomogeneity or other anisotropic microstructural defects may trigger stress concentration phenomena responsible for the early collapse of the device. Metal manufacturing processes play a fundamental role towards the final microstructure and mechanical properties of the materials. The present work assesses the effect of mode of rolling on the micro-texture evolution, mechanical properties and biodegradation behaviour of polycrystalline pure iron. Results indicated that cross-rolled samples recrystallized with lower rates than the straight-rolled ones due to a reduction in dislocation density content and an increase in intensity of {100} crystallographic plane which stores less energy of deformation responsible for primary recrystallization. The degradation resulted to be more uniform for cross-rolled samples, while the corrosion rates of cross-rolled and straight-rolled samples did not show relevant differences in simulated body solution. Finally, this work shows that an adequate compromise between biodegradation rate, strength and ductility could be achieved by modulating the deformation mode during cold rolling.

On the long term antibacterial features of silver-doped diamondlike carbon coatings deposited via a hybrid plasma process.

Environmental surfaces are increasingly recognized as important sources of transmission of hospital-acquired infections. The use of antibacterial surface coatings may constitute an effective solution to reduce the spread of contamination in healthcare settings, provided that they exhibit sufficient stability and a long-term antibacterial effect. In this study, silver-incorporated diamondlike carbon films (Ag-DLC) were prepared in a continuous, single-step plasma process using a hybrid, inductively coupled plasma reactor combined with a very-low-frequency sputtering setup. The average Ag concentration in the films, ranging from 0 to 2.4 at. %, was controlled by varying the sputtering bias on the silver target. The authors found that the activity of Escherichia coli was reduced by 2.5 orders of magnitude, compared with the control surface, after a 4-h contact with a 2.4 at. % Ag-DLC coating. The coatings displayed slow release kinetics, with a total silver ion release in the sub-ppb range after 4 h in solution, as measured by graphite furnace-atomic absorption spectroscopy. This was confirmed by Kirby-Bauer diffusion tests, which showed limited diffusion of biocidal silver with a localized antibacterial effect. As a slow and continuous release is mandatory to ensure a lasting antibacterial effect, the newly developed Ag-DLC coatings appears as promising materials for environmental hospital surfaces.

Mutant huntingtin is present in neuronal grafts in Huntington disease patients.

OBJECTIVE: Huntington disease (HD) is caused by a genetically encoded pathological protein (mutant huntingtin [mHtt]), which is thought to exert its effects in a cell-autonomous manner. Here, we tested the hypothesis that mHtt is capable of spreading within cerebral tissue by examining genetically unrelated fetal neural allografts within the brains of patients with advancing HD. METHODS: The presence of mHtt aggregates within the grafted tissue was confirmed using 3 different types of microscopy (bright-field, fluorescence, and electron), 2 additional techniques consisting of Western immunoblotting and infrared spectroscopy, and 4 distinct antibodies targeting different epitopes of mHtt aggregates. RESULTS: We describe the presence of mHtt aggregates within intracerebral allografts of striatal tissue in 3 HD patients who received their transplants approximately 1 decade earlier and then died secondary to the progression of their disease. The mHtt(+) aggregates were observed in the extracellular matrix of the transplanted tissue, whereas in the host brain they were seen in neurons, neuropil, extracellular matrix, and blood vessels. INTERPRETATION: This is the first demonstration of the presence of mHtt in genetically normal and unrelated allografted neural tissue transplanted into the brain of affected HD patients. These observations raise questions on protein spread in monogenic neurodegenerative disorders of the central nervous system characterized by the formation of mutant protein oligomers/aggregates.