Silver-Containing Thin Films on Transparent Polymer Foils for Antimicrobial Applications

Abstract

The increasing occurrence of infections caused by pathogens found on objects of everyday use requires a variety of solutions for active disinfection. Using active materials that do not require daily maintenance has a potential advantage for their acceptance. In this contribution, transparent films, with silver as the main antimicrobial agent and a total thickness of a few tens of nm, were deposited on flexible self-adhesive polymer foils used as screen protectors. TiO2 and SiO2 were used as transparent matrix to embed the Ag nanoparticles, ensuring also their mechanical protection and controlled growth. HiPIMS (High-Power Impulse Magnetron Sputtering) was used for the sputtering of the Ag target and fine control of the Ag amount in the layer, whereas TiO2 and SiO2 were sputtered in RF (Radio Frequency) mode. The thin film surface was investigated by AFM (Atomic Force Microscopy), providing information on the topography of the coatings and their preferential growth on the textured polymer foil. XRD (X-Ray Diffraction) revealed the presence of specific Ag peaks in an amorphous oxide matrix. UV-Vis-NIR (Ultraviolet-Visible-Near Infrared) spectroscopy revealed the presence of nanostructured Ag, characterized by preferential absorption in the 400 to 500 nm spectral range. The antimicrobial properties were assessed using an antimicrobial test with the Escherichia coli strain. The highest efficiency was observed for the Ag/SiO2 combination, in the concentration range of 104–105 CFU/mL.

Synthesis and Investigation of Antibacterial Activity of Thin Films Based on TiO2-Ag and SiO2-Ag with Potential Applications in Medical Environment

“…Partial results of this work were published and described the synthesis of TiO 2 -Ag and SiO 2 -Ag films deposited on polyurethane self-adhesive substrates by a combined sputtering technique, namely RF sputtering for the oxide and HiPIMS for Ag, and also the complete structural characterization and evaluation of the antimicrobial activity at 24 and 48 h for the films in contact with Escherichia coli suspensions of concentrations 10 5 CFU/mL and 10 4 CFU/mL [ 39 ]. In addition, in this paper, the advantages and the novelty of the study are included, as well as the extension of tests in different conditions, which are described below.…”

Antimicrobial Nanomaterials: A Review

“…Thus, coating the objects that we use every day with antimicrobial films is considered to be quite an effective method of disinfection. Vitelaru et al produced transparent antimicrobial films that were a few tens of nanometers thick and intended for use as screen protective films [2]. They placed these films on a self-adhesive polyurethane foil.…”

“…Pathogenic infectious agents that form biofilms remain alive on surfaces for a long time. It is also known that multi-drug-resistant bacterial strains can survive for weeks on different surfaces in the hospital [2]. The National Institute of Health announced that biofilms are responsible for 80% of the total number of microbial infections in humans [3], including meningitis, cystic fibrosis, kidney infections, endocarditis, rhinosinusitis, periodontitis, non-healing chronic wounds, osteomyelitis, prosthetic, and implantable medical device infections [4].…”

Recent Trends in Antibacterial Coatings and Biofilm

“…In addition to natural bioactive compounds, inorganic antimicrobial compounds comprising metal or metal oxide nanoparticles, such as silver or hydroxyapatite or other metal oxides, have been intensively studied, with outstanding results [14,17,18]. Silver nanoparticles can be integrated in TiO 2 and SiO 2 translucent matrices with the help of high-power impulse magnetron sputtering and radio frequency, and display efficient antimicrobial properties against E. coli [17]. Antibacterial TiO 2 was also applied to produce a titaniapolyurea coating that presented efficient activity against P. aeruginosa.…”

“…Antibacterial TiO 2 was also applied to produce a titaniapolyurea coating that presented efficient activity against P. aeruginosa. Besides using these biopolymers in food packaging, they can also be applied as antimicrobial coatings in sectors such as the medical field, pharmaceutics, electronics, and the cosmetics industry [17][18][19][20]. Recently, several studies incorporated antibacterial substances in biopolymers, for instance, fluoroquinolone antibiotics; these can also be efficiently used in the medical field [20,21].…”