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In this study, multifunctional stratified antibacterial and bioactive coatings were deposited and characterised. Initially, PEEK/bioactive glass (BG)/ mesoporous bioactive glass nanoparticle (MBGN) layers with a thickness of 110–120 μm were deposited on stainless steel substrates using electrophoretic deposition (EPD). Thin silver nanocluster-silica composite layers with a thickness of 70–155 nm were then deposited by radio frequency (RF) co-sputtering on the previously deposited EPD coatings. The deposition was carried for two different sputtering times (20 min and 40 min), which led to different layer thicknesses. PEEK/BG/MBGNs coatings were also deposited via single-step EPD. A comparison between the physicomechanical and biological characteristics of single layer PEEK/BG/MBGNs composite coating and bilayer Ag-PEEK/BG/MBGNs is presented. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) indicated that silver nanoclusters were homogeneously distributed in the multilayered EPD/RF coatings. An apatite-like structure was formed on the surface of the coatings upon immersion in simulated body fluid (SBF) after 1 day. Silver nanoclusters embedded in the silica matrix as a top layer provided controlled release of silver ions which led to a potent antibacterial effect against E. coli and S. carnosus. Single layer coatings exhibited a burst release of Ag ions, which led to antibacterial effects but were toxic to osteoblast cells. Finally, the results of WST-8 assays confirmed that the multi-structured coatings allow osteoblast-like cells to proliferate and attach strongly on the surface of the coatings. [ABSTRACT FROM AUTHOR]

This study aims at deposition and characterization of antibacterial, hydrophobic and semitransparent metal/plasma polymer nanocomposite coating, containing Ag nanoparticles, onto cotton fabrics intended to be used in medical applications. The nano composite coatings were obtained via a simple, one step and ecofriendly plasma based co-deposition approach where silver was magnetron sputtered simultaneously with plasma polymerization of hexamethyldisiloxane (HMDSO) monomer. The nanocomposite thin films containing different concentration of silver were deposited either by varying silver sputter rate or thickness of the plasma polymer matrix to obtain a good balance between optical properties of the coated fabric and its long term antibacterial performance. The obtained coatings were investigated in detail with respect to their composition, morphology, optical properties, nanoparticle size distribution, silver ion release efficiency, antibacterial performance, water contact angle and washing stability of the coating. The thickness of the plasma matrix was found to be more important in controlling the release of silver ions as well as affecting the optical properties of the coating. The water contact angle on the coated fabric was up to 145°, close to super hydrophobicity. The coating showed effective antibacterial efficacy against Staphylococcus epidermidis (a Gram positive bacterium) which was present even when fabric was subjected to 10 repeated washing cycles indicating good washing stability of the coating. [ABSTRACT FROM AUTHOR]

Excellent mechanical, thermal and chemical properties make Vectran™ fibres an attractive material to be used in high end applications. Its aerospace applications, as in inflatable light weight habitat module, require functional coating to provide antibacterial protection to ensure safe environment for the astronauts. In this study, woven Vectran™ fabric was coated with an antibacterial silver nanoclusters/silica composite coating by means of radio frequency co-sputtering technique. The successful deposition of the silver nanoclusters embedded in the silica matrix of the composite coating was confirmed by morphological, compositional and structural analysis. The coating sustained 10 washing cycles with partial dissolution of the coating during washing. Silver leaching test verified the gradual and progressive release of ionic silver in aqueous media in the range 0.03 ppm–0.43 ppm within 72 h of immersion in water. Antibacterial properties of the coated Vectran™ fabric were confirmed in inhibition halo test against Staphylococcus aureus and Escherichia coli on as deposited as well as aged samples. An inhibition halo of up to 2 mm was observed for as deposited samples while after UV exposure, the samples formed inhibition halo of 4 mm. The percutaneous absorption test demonstrated a very low release of silver into epidermis and dermis. The effect of the coating on mechanical properties of the as deposited Vectran fabric was assessed through mechanical characterizations including tensile, tear and abrasion test. • Uniform coverage and distribution of silver nanoclusters on the fibre surface • Gradual release of silver ions from the composite coating • Satisfactory washing resistance of the composite coating • Mechanical properties of the fabric preserved [ABSTRACT FROM AUTHOR]

High performance textiles such as Kevlar® find large use in many applications including aerospace field, thus require antimicrobial characteristics to avoid the risk of microbial contamination on board of spacecraft and orbital station during prolonged space exploration missions. In this study, Kevlar® fabric has been coated with antibacterial silver nanocluster/silica composite layer with different thicknesses, by means of radio frequency co-sputtering technique. The fibers morphology and composition has been analyzed by means of field emission scanning election microscopy (FESEM), energy dispersion spectrometry (EDS), x-ray photoelectron spectroscopy (XPS). Thermal properties have been evaluated through thermogravimetric experiments (TGA) and differential scanning calorimetry (DSC). The fibers result homogenously coated with the antibacterial layer composed of silica matrix embedding silver nanoclusters. A controlled and gradual release of silver was observed in silver leaching tests in water and artificial sweat. The antimicrobial behavior is verified through inhibition halo and broth dilution tests against different bacterial and fungal species. The in vitro skin penetration test shows that the Ag amount absorbed through the skin is mainly stored in epidermis. Tensile and tear properties were maintained and not degraded by the coating deposition. The reduction of perforation resistance after coating deposition could be considered negligible whereas abrasion test demonstrated an increased resistance of coated sample. [ABSTRACT FROM AUTHOR]