Search

The indoor air quality should be better controlled and improved to avoid numerous health issues. Even if different devices are developed for air filtration, the proliferation of microorganisms under certain conditions must be controlled. For this purpose, a silver nanocluster/silica composite coating was deposited via a cosputtering technique onto fiber glass and polymeric based substrates. The aim of this work is focused on the evaluation of the antibacterial and antiviral effects of the developed coating. The preliminary results of the compositional and morphological tests showed an evenly distributed coating on filters surfaces. Several antibacterial tests were performed, confirming strong effect both in qualitative and quantitative methods, against S. epidermidis and E. coli . To understand if the coating can stop the proliferation of bacteria colonies spread on it, simulation of everyday usage of filters was performed, nebulizing bacteria solution with high colonies concentration and evaluating the inhibition of bacteria growth. Additionally, a deep understanding of the virucidal action and mechanism of Ag nanoclusters of the coating was performed. The effect of the coating both in aqueous medium and in dry methods was evaluated, in comparison with analysis on ions release. The virucidal performances are assessed against the human coronavirus OC43 strain (HCoV-OC43).

Hernias are generally repaired using synthetic prostheses. Infection may already be present or develop during implantation. Based on the increasing resistance to antibiotics, and the well-known antimicrobial properties of silver (Ag), the possibility of coating hernia prostheses with a nanostructured layer containing Ag was explored. Prostheses (Clear Mesh Composite [CMC]) made up of two polypropylene layers (macroporous light mesh and thin transparent film) were tested with human mesothelial cells from omentum biopsies. Mesotheliocytes modulate abdominal wall healing producing cytokines, growth factors, and adhesion molecules. Evaluating the growth of these cells on CMC or film alone showed that cell numbers on CMC increased over time, and were higher than those on film alone. Vimentin immunostaining confirmed the cells to be mesotheliocytes. Subsequently, the biocompatibility of mesh layer, coated or not with a thin layer of Ag/SiO 2 -nanoclusters, was analyzed, showing no difference in absence or presence of Ag/SiO 2 . Differently, TGF-β2 production, involved in tissue repair and fibrosis, increased in the presence of Ag/SiO 2 . Moreover, Ag/SiO 2 -coated mesh showed antibacterial properties. In conclusion, the mesh layer coated with Ag/SiO 2 afforded cell growth, and showed antibacterial activity. Coating only the mesh layer did not decrease film transparency, and did not favor the formation of adhesions on the visceral side. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1586-1593, 2017., (© 2016 Wiley Periodicals, Inc.)

Discouraging bacterial colonization of ocular biomaterials and implants is a significant challenge in ophthalmology as infections often lead to the need for secondary surgery, with associated risks and additional stress to patients. In this work we demonstrate for the first time the feasibility of an innovative antibacterial ocular prosthesis produced by depositing a silver nanocluster/silica composite layer on the poly(methyl methacrylate) implant surface via radio-frequency sputtering. Tape test performed according to relevant ASTM standard provided a preliminary evidence of the mechanical stability and good adhesion of the coating to the substrate (absence of macroscopic damage after tape removal). Coating integrity was maintained after prolonged soaking in aqueous medium (1 month). The antibacterial effect of the coating, associated to silver ion release upon contact with aqueous fluid, was confirmed by the in vitro formation of a 5-mm inhibition halo test against Staphylococcus aureus that is one of the most common bacteria involved in ocular infections. The approach proposed in the present study for facing implant-related ocular infections can have a significant impact in the field of ophthalmic biomaterials, suggesting a valuable alternative to the administration of antibiotics that may become ineffective due to bacterial resistance., (Copyright © 2015 Elsevier B.V. All rights reserved.)

• 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]

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]

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]