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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]

High photocatalytic activity layers were obtained by combining a TiO 2 nanostructured coating support with 10 nm and 20 nm NiO layers synthesized by direct current (DC) magnetron sputtering. In order to improve the TiO 2 crystallinity several sputtering process parameters were studied. The TiO 2 and NiO/TiO 2 coatings were characterized through XPS, XRD, FESEM, AFM and UV transmittance measurements, in the latter case, for band gap determination. The photocatalytic activity of the coatings was tested through methylene blue degradation under UV light. The formation of a p-n heterojunction between the TiO 2 and NiO layers improved the degradation rates, compared to the bare TiO 2 layers; however, almost no difference can be seen when increasing the NiO sputtering power and subsequently the coating thickness to higher values than 20 nm. [ABSTRACT FROM AUTHOR]

Abstract: The microbiological contamination on board of spacecraft and orbital stations is a relevant problem in prolonged space exploration. For this purpose, an antibacterial silver nanocluster silica composite coating was deposited on a commercial polymer Combitherm®, suitable for aerospace application, using the radio frequency (RF) co-sputtering technique. The presence of metallic silver nanoclusters and silica was confirmed by energy dispersion spectrometry (EDS), x-ray photoelectron spectroscopy (XPS) and localized surface plasmon resonance (LSPR) detected through UV–visible absorption spectrophotometry (UV–Vis). The atomic force microscope (AFM) evidenced the coating morphology. The slight hydrophobicity of both coated and uncoated samples was revealed through the contact angle measurement. The antimicrobial behavior was verified through evaluation of the inhibition halo against several bacterial and fungal species. The coating enhanced the Combitherm® nano-hardness and its resistance to tensile and perforation tests; the coating wear resistance was measured by abrasion test against Kevlar. A folding procedure on the coated Combitherm® and storage in air for three months was also carried out without deterioration of the measured properties. The coating deposition did not influence the air permeability of Combitherm®. [Copyright &y& Elsevier]

Abstract: Silver nanocluster–silica composite coatings have been deposited by radio frequency (RF) co-sputtering on silica substrates. UV–visible absorption and X-ray diffraction spectra of the as deposited and heated samples revealed metal silver nanoclusters of different size, depending on the annealing treatment. The antibacterial activity of several as deposited and annealed samples has been verified in accordance to National Committee for Clinical Laboratory Standards (NCCLS). The antibacterial activity of these coatings was detected up to 450°C. [Copyright &y& Elsevier]

• Ag nanoclusters- SiO 2 /Al 2 O 3 /ZrO 2 coatings were obtained on SS316L, Tigr4 and Tigr5 by co-sputtering. • All coatings have a mean roughness <0.2 µm and good mechanical adhesion to the substrate. • ZrO 2 based coatings are the most stable in wet environment. • ZrO 2 -Ag coatings can reduce S. aureus adhesion even if Ag release is negligible. • ZrO 2 -Ag coatings are promising for temporary fixation devices. Bacterial contamination and bone tissue overgrowth are currently the main issues for temporary fixation devices. The aim of this research is the development of innovative inorganic coatings able to reduce bacterial adhesion and bone tissue overgrowth without hampering cytocompatibility. 316L stainless-steel, Titanium grade4 and Titanium grade5 were selected as substrates, as currently used in temporary fixation devices. Starting from previous results on silica, alumina and zirconia were selected as coating matrices, according to their higher chemical stability, reduced bacterial adhesion and possible reduction of tissue overgrowth. Coatings were produced by co-sputtering. Coating adhesion was evaluated by tape test. Samples were immersed in ultrapure water up to 28 days to investigate silver release and chemical stability in fluids. Surface roughness was measured by contact profilometry. Surface wettability was determined by contact angle measurements and antibacterial activity was studied against antibiotic resistant S aureus. The research demonstrates the possibility to obtain coatings with roughness lower than the critical threshold for the increase of bacterial adhesion (0.2 µm) and optimal mechanical adhesion to metallic substrates. Coating chemical stability in water is strongly affected by the coating matrix composition. Silver release can be tailored to obtain antibacterial and biocompatible surfaces. [ABSTRACT FROM AUTHOR]

With the goal of preventing abdominal infections after implanting prostheses for hernia repair, polypropylene prostheses were coated with a silver nanoclusters-silica composite (Ag/SiO 2 ) layer, by means of a sputtering process, to confer antibacterial properties. The Ag/SiO 2 coating was deposited, with good uniformity and adhesion, either onto hernia prostheses (CMC) made of two polypropylene layers (macroporous light mesh and thin transparent film), or onto the mesh layer alone. The coating was optimized to achieve a good balance between antibacterial activity and biocompatibility. Antibacterial activity, fibroblast growth on CMC/mesh layer alone, in the presence/absence of Ag/SiO 2 , collagen, and some cytokines involved in inflammation and healing processes, were determined. Preliminary experiments showed that when both layers of CMC were entirely coated, antibacterial properties were achieved while losing prosthesis biocompatibility. Coating the entire CMC was a complex process, thus for subsequent experiments the mesh layer alone was coated, being the antibacterial properties unaffected by this choice and the mesh the part of CMC exposed to possible infection. With a duty cycle of 1 s over 24 on an Ag target, for 15 min deposition time, antibacterial activity, evaluated through the quantitative Colony–Forming Units test, was positive; fibroblasts colonized the coated mesh layer and produced collagen. Cell viability analysis showed that most cells were viable at all experimental times. Moreover, IL-1β and IL-6 decreased, and TGF-β2 increased, in fibroblasts seeded on mesh layer coated with Ag/SiO 2 versus that without Ag/SiO 2 . Ag/SiO 2 -coated mesh layers allowed fibroblast growth and activity, without inducing cell death via apoptosis or necrosis and, at the same time, provided antibacterial activity. [ABSTRACT FROM AUTHOR]

Titanium alloys possess poor resistance to friction and this adversely affects the corrosion behavior and osseointegration of the implants made from these alloys. Nanostructured PVD coatings with biocompatibility, anti-wear and anti-corrosion characteristics have attracted much attention in biomedical applications. In this study, TiN and ZrN single layer and CrN/TiN and CrN/ZrN nanostructured multilayer thin films were applied on a Ti6Al4V substrate by means of cathodic arc PVD technique. The physical-chemical characterization of the coatings was conducted using FE-SEM, EDS, and XRD analyses. Their surface topography and wettability were measured. In addition, the hardness and adhesion strength were evaluated by means of Knoop microhardness and scratch tests, respectively. Also, the apatite-forming ability of the coatings was investigated through SEM, EDS and, FTIR. The corrosion performance of the coatings was studied using PDP and EIS assessments in SBF solution. According to the findings, the multilayer coatings have higher hardness and scratch resistance than single layers. The coating delamination tacked place in L c equal 39.6 (N) and 39.3 (N) for CrN/TiN and CrN/ZrN coatings, respectively. The corrosion assessments revealed that the CrN/ZrN multilayer coating exhibited the best corrosion resistance due to its smoother surface and more dense structure in addition to its specific architecture. The ZrN single layer and CrN/ZrN multilayer coatings showed a better hydroxyapatite precipitation; however, all surfaces had satisfactory bioactivity. In all, this study showed that CrN/ZrN nanostructured multilayer thin film is potentially suitable candidate for orthopedic and dental implants. [ABSTRACT FROM AUTHOR]