Silver Nanocluster/Silica Composite Coatings Obtained by Sputtering for Antibacterial Applications

Abstract

Silver nanocluster silica composite coatings were deposited by radio frequency co-sputtering technique on several substrates. This versatile method allows tailoring of silver content and antibacterial behaviour of coatings deposited on glasses, ceramics, metals and polymers for several applications. Coating morphology and composition as well as nanocluster size were analyzed by means of UV-Visible absorption, X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), electron dispersive spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The antibacterial effect was verified through the inhibition halo test against standard bacterial strain, Staphylococcus aureus, before and after sterilization process. Tape test demonstrated a good adhesion of the coatings to the substrates.

How can bioactive glasses be useful in ocular surgery?

“…The coating, whose thickness can be modulated from 10 nm to 1 lm, is produced by radiofrequency cosputtering of silver and silica and is constituted by silver nanoclusters embedded in an amorphous silica (silica glass) matrix. The antiseptic effect was demonstrated in vitro (using S. aureus) and is due to the release of silver ions, [95][96][97] that are not associated to problems of bacterial resistance like in the case of antibiotic treatments. This approach is promising but further in vitro tests with the relevant cell types (e.g., orbital fibroblasts) and in vivo studies in an animal model have to be performed to draw definite conclusions about the suitability of the coating: in fact, the ocular environment is highly complex and several parameters should be taken in account, including the solubility of the silica matrix, the interaction of released metal ions with the tears and the possible ion-induced eye tissue necrosis.…”

Elucidating the role of environmental management of forests, air quality, solid waste and wastewater on the dissemination of SARS-CoV-2

“…Other reported high filtration materials include microfibers, shop towels, coffee filters and lycra cloths ( Hao et al, 2021 ), however need wider testing. Additionally, disposable facial FFP3 masks for essential workers have been suggested to be coated with silver nanocluster/silica composite, which is a low-cost material ( Balagna et al, 2013 ; Balagna et al, 2020 ). It has been advised that healthcare workers must use N95 or medical grade masks which could be reused for 7-10 days after steaming for two hours as a low-cost decontamination method ( Adeniran et al, 2021 ; Ma et al, 2020 ).…”

Novel antibacterial ocular prostheses: Proof of concept and physico-chemical characterization

“…This strategy is expected to overcome the drawbacks of the antibacterial device proposed by Yang et al [14], including the toxicity of the released nanosilver and the high cost of the metal nanoparticles to be incorporated in the bulk of the prosthesis. Our approach is founded on the use of RF sputtering, that is recognized as a versatile technique adopted to obtain coatings with different features and intended for a wide range of applications [20,21]; among them, the ability to deposit antibacterial layers on various surfaces for healthcare, clinical or, in general, everyday use has received increasing attention in the last years [22][23][24][25][26]. For the first time, this work reports the feasibility and characterisation of silver nanocluster/silica composite antibacterial coatings deposited on the rear surface of PMMA ocular prostheses to be used in contact with the patient's conjunctiva (Fig.…”