Fabrication of metal microfibers by melt-spinning

Metal microfibers have a wide range of industrial applications, e.g. as filters, fiber-reinforced composites, electrodes, catalysts, sensors, or magnetic shielding materials. In this project, we modified melt-spinning device and its experimental parameters to fabricate metal microfibers. It was shown for the first time that metal microfibers down to 5 μm could be fabricated using a melt spinning device. The size and circularity of formed fibers could be controlled by experimental parameters.e.g. slit distance to the wheel, chamber pressure, slit size, wheel speed. The mechanism of fiber formation relies on two main steps; i)thin film formation on the rotating wheel ii)spontaneous breaking of the film to smaller widths, dewetting the wheel. It was shown that this process is reproducible and could be used for different classes of materials. e.g. intermetallic alloys, conventional alloys, metal elements and amorphous alloys. The modification of the melt spinning device leads to higher quenching rates up to 108!C/s. The high quenching rate made it possible to make fully amorphous stainless steel fibers for the very first time. Heat-treatment of amorphous stainless steel leads to dual-phase microstructure (nanocrystals embedded together with a glassy phase) which was responsible for its ultra-high hardness value, 14GPa. This value is 7 times higher than the original stainless steel hardness. Thus, the technique opens new possibilities for working with conventional and amorphous alloys e.g. mechanically improved conventional alloy microfibers/ribbons, introducing new alloy microstructures

Fabrication of stainless-steel microfibers with amorphous-nanosized microstructure with enhanced mechanical properties

Metallic glasses (MG) have attracted much attention due to their superior hardness and good corrosion resistance. However, designing new MG compositions is still a big challenge, and their integration into different systems is limited when they are in the shape of bulk materials. Here, we present a new method for the fabrication of MG in the form of microfibers which could greatly help them to be integrated within different systems. The newly proposed technique has the ability to form MG structure from commercially available alloy compositions thanks to its significantly improved quenching rate(similar to 10(8) K.s(-1)). In this technique, individual melt droplets are ejected on a rotating wheel forming a thin film which are ruptured upon solidification leading to the formation of MG microfibers. In this regard, we have fabricated microfibers from a commercial DIN 1.4401 stainless-steel which could form a completely amorphous structure confirmed by DSC, XRD, and HRTEM. The fabricated MG microfibers show an increased hardness for more than two-fold from 3.5 +/- 0.17 GPa for the as-received stainless-steel to 7.77 +/- 0.60 GPa for the amorphous microfibers. Subsequent heat-treatment of the microfibers resulted in a nanocrystalline structure with the presence of amorphous regions when the hardness increases even further to 13.5 +/- 2.0 GPa. We propose that confinement of both shear transformation zones and dislocations in the heat-treated MG microfibers plays a major role in enhancing strength

Generation of cytocompatible superhydrophobic Zr–Cu–Ag metallic glass coatings with antifouling properties for medical textiles

Zirconium–Copper-based metallic glass thin films represent promising coatings in the biomedical sector for their combination of antibacterial property and wear resistance. However, finding a Zr–Cu metallic glass composition with desirable cytocompatibility and antibacterial property is extremely challenging. In this work, we have created a cytocompatible and (super-)hydrophobic Zr–Cu–Ag metallic glass coating with ≈95% antifouling properties. First, a range of different chemical compositions were prepared via Physical Vapor Deposition magnetron by co-sputtering Zr, Cu, and Ag onto a Polybutylene terephthalate (PBT) substrate among which Zr93·5Cu6·2Ag0.2, Zr76·7Cu22·7Ag0.5, and Zr69·3Cu30·1Ag0.6 were selected to be further investigate for their surface properties, antibacterial activity, and cytocompatibility. Scanning electron microscopy (SEM) images revealed a micro-roughness fibrous structure holding superhydrophobic properties demonstrated by specimens' static and dynamic contact angle measurements ranging from 130° to 150°. The dynamic contact angle measurements have shown hysteresis below 10° for all coated samples which indicated the superhydrophobicity of the samples. To distinguish between antifouling and bactericidal effect of the coating, ions release from coatings into Luria Bertani Broth (LB), and Dulbecco's Modified Eagle Medium (DMEM) solutions were evaluated by inductively coupled plasma mass spectrometry (ICP-MS) measurements after 24 ​h and 5 days. Antifouling properties were evaluated by infecting the specimens' surface with the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli strain reporting a ≈95% reduction of bacteria adhesion as visually confirmed by FESEM and fluorescent live/dead staining. Human mesenchymal stem cells (hMSC) were used for direct cytocompatibility evaluation of coated samples and their metabolic activity was evaluated via relative fluorescence unit after 24 ​h and 5 days confirming that it was comparable to the controls (>97% viable cells). The results were further visualized by FESEM, fluorescent staining by Live/Dead Viability/Cytotoxicity Kit and confirmed the cytocompatibility of all coated samples. Finally, hMSC′ cytoplasm was stained by May Grunwald and Giemsa after 5days to detect and visualize the released ions which have diffused through the cells' membrane

Matrixyl Patch vs Matrixyl Cream: A Comparative In Vivo Investigation of Matrixyl (MTI) Effect on Wound Healing

[Image: see text] Wound healing is one of the most complex biological processes. Studies show that Matrixyl (MTI), known as a cosmetic peptide, can lead to a faster healing process. The contribution of MTI to collagen formation during wound healing also depends on its mode of delivery and its release over time. Here, we investigate two modes of MTI-delivery system, the influence of MTI patch for wound healing application in comparison with MTI cream. In this study, animals were randomly divided into seven groups and studied for 21 days: patches containing two different concentrations of MTI (P-MTI-0.1 mg and P-MTI-1 mg), a cream containing MTI (C-MTI-1 mg), a patch (P-MTI-0), a cream with no MTI (C-MTI-0), a positive control (Comfeel), and a negative control (sham) group. To study the wound healing process, the change in collagen density, angiogenesis, epitheliogenesis, histopathology, immunohistochemical analysis, and wound area through imaging was monitored and measured. The macroscopic results showed that wound healing was improved from 63.5 up to 81.81% in treatment groups compared to that in the negative control group (P < 0.05 and P < 0.001). In addition, C-MTI-1 and P-MTI-1 had a larger impact on wound healing compared to that in the positive control group (Comfeel, P < 0.05). In hematoxylin and eosin (H&E) staining analysis, the rejuvenation of skin appendage was visible in both groups of cream and patches with MTI. According to the obtained results, the re-epithelialization had a higher range for the patch with MTI in comparison with cream containing MTI and positive control

Antibacterial activity, cytocompatibility, and thermomechanical stability of Ti40Zr10Cu36Pd14 bulk metallic glass

This paper envisions Ti40Zr10Cu36Pd14 bulk metallic glass as an oral implant material and evaluates its antibacterial performance in the inhabitation of oral biofilm formation in comparison with the gold standard Ti-6Al-4V implant material. Metallic glasses are superior in terms of biocorrosion and have a reduced stress shielding effect compared with their crystalline counterparts. Dynamic mechanical and thermal expansion analyses on Ti40Zr10Cu36Pd14 show that these materials can be thermomechanically shaped into implants. Static water contact angle measurement on samples' surface shows an increased surface wettability on the Ti-6Al-4V surface after 48 h incubation in the water while the contact angle remains constant for Ti40Zr10Cu36Pd14 . Further, high-resolution transmission and scanning transmission electron microscopy analysis have revealed that Ti40Zr10Cu36Pd14 interior is fully amorphous, while a 15 nm surface oxide is formed on its surface and assigned as copper oxide. Unlike titanium oxide formed on Ti-6Al-4V, copper oxide is hydrophobic, and its formation reduces surface wettability. Further surface analysis by X-ray photoelectron spectroscopy confirmed the presence of copper oxide on the surface. Metallic glasses cytocompatibility was first demonstrated towards human gingival fibroblasts, and then the antibacterial properties were verified towards the oral pathogen Aggregatibacter actinomycetemcomitans responsible for oral biofilm formation. After 24 h of direct infection, metallic glasses reported a >70% reduction of bacteria viability and the number of viable colonies was reduced by similar to 8 times, as shown by the colony-forming unit count. Field emission scanning electron microscopy and fluorescent images confirmed the lower surface colonization of metallic glasses in comparison with controls. Finally, oral biofilm obtained from healthy volunteers was cultivated onto specimens' surface, and proteomics was applied to study the surface property impact on species composition within the oral plaque

Inductively coupled plasma mass spectrometry of ions released from the coating into LB and DMEM medium

several coatings from the ternary alloy of Zr-Cu-Ag metallic glasses (fabricated by PVD magnetron co-sputtering) were tested by the mass spectroscopy to evaluate their ion release in LB and DMEM. LB is the common medium for bacterial culture while DMEM is common for cells. coated samples have the name SP in them, while the non-coated one is PBT. They were in orbital shaker at 37˚C, 120 rpm for 1 day, 3 days and 7 days.This study can help understand the underlying mechanism of antibacterial activity of Zr-Cu-Ag metallic glass coatings. Marie Skłodowska-Curie Individual Fellowship (MSCA-IF-EF-ST) Horizon 2020 - Research and Innovation Framework Programme Grant Agreement Number: 892050 Project Acronym: MAGIC Project title: [Development of antibacterial MetAllic Glass mICrofibers] Principal Investigator: Elham Sharifikoloue

Indirect cytocompatibility and antibacterial properties of Zr-Cu-Ag metallic glass coatings

In order to evaluate a possible antibacterial effect of the released ions, specimens (4x4 mm2 square metallic glass coatings) were submerged with 7 ml of LB broth and maintained at 37°C inside a shaker (120 rpm) for 1, 5 days, following the same procedure exploited for the ions release evaluation. At each time point the supernatants were collected and used to cultivate bacteria at a defined concentration (1x105 cells/ml); bacteria cultivated with supernatants obtained from ions-free PBT were considered as control. The released ions killing activity was evaluated in terms of metabolic activity that was measured by the alamar blue assay as previously detailed. The same procedure with LB medium for hMSC was repeated.Marie Skłodowska-Curie Individual Fellowship (MSCA-IF-EF-ST) Horizon 2020 - Research and Innovation Framework Program Grant Agreement Number: 892050 Project Acronym: MAGIC Project title: [Development of antibacterial MetAllic Glass mICrofibers] Principal Investigator: Elham Sharifikoloue

small angle x-ray scattering from Zr-Cu-Ag metallic glass coatings

small angle x-ray scattering from Zr-Cu-ag metallic glass coating to confirm whether they became amorphous or not. The coating is on PBT substrate.Marie Skłodowska-Curie Individual Fellowship (MSCA-IF-EF-ST) Horizon 2020 - Research and Innovation Framework Programme Grant Agreement Number: 892050 Project Acronym: MAGIC Project title: [Development of antibacterial MetAllic Glass mICrofibers] Principal Investigator: Elham Sharifikoloue

static water contact angle measurements of Ti40Zr10Cu36Pd14 bulk metallic glass and Ti6Al4V surfaces

static water contact angle measurements of Ti40Zr10Cu36Pd14 bulk metallic glass and Ti6Al4V surfaces: the measurments were first taken place on their etched surface and was repeated after they were incubated in orbital shaker in distilled water at 37˚C and 120 rpm for 48 hours.The project received funding from Austrian Science Fund (FWF) under project grant I3937–N36, ERC Proof of Concept Grant TriboMetGlass (grant ERC-2019-PoC-862485). financial support by the Austrian Science Fund (FWF) under the project grant T891-N36. Thanks to European Commission for providing funding for this project under the Horizon 2020 research and innovation program for Marie Skłodowska-Curie Individual Fellowship, with the acronym "MAGIC" and grant agreement N. 892050

FESEM after antibacterial test on Ti- bulk metallic glass compared with Ti6Al4V

Field Emission scanning electron microscopy of Ti40Zr10Cu36Pd14 and Ti6Al4V after 24 h of antibacterial test with AggregatibacterMarie Skłodowska-Curie Individual Fellowship (MSCA-IF-EF-ST) Horizon 2020 - Research and Innovation Framework Program Grant Agreement Number: 892050 Project Acronym: MAGIC Project title: [Development of antibacterial MetAllic Glass mICrofibers] Principal Investigator: Elham Sharifikoloue