Antibacterial efficiency over time and barrier properties of wood coatings with colloidal silver

Abstract

This work aims to represent a standard application for understanding the extent of the antibacterial efficacy of coatings with different amounts of colloidal silver on wooden surfaces over time. The key variable that was intended to be evaluated in this study was the “time efficiency,” with concerns about the possible efficacy in the durability of the surfaces. By highlighting the “expiry date” of the agents, as in the case with other products, the study aimed to confirm the validity of the simulation tests conducted in the laboratory with degradation tests. Furthermore, the role of the silver amount on the barrier performance of the coatings was assessed by liquid resistance, water uptake, and perspiration tests, evaluating the aesthetic durability of the coatings by means of colorimetric analyses. Ultimately, this work demonstrates that these coatings may represent alternatives in terms of prolonged antimicrobial activity when compared with the biocide agents currently in use, capable to offer good resistance to detergent solutions and to water. Nevertheless, due to silver’s susceptibility to extended exposure to acidic solutions, the findings of the research discourage the utilization of colloidal silver in wood paints intended for use in public settings. Key points • Colloidal silver does not alter the deposition process and does not introduce defects in the wood paint. • Coatings containing silver show high antimicrobial activity over time, against both E.coli and S.aureus. • The silver-based filler resists contact with detergents and aqueous solutions but suffers oxidation processes in acidic environments.

Bacterial growth dynamics on a surface having a particulate antimicrobial agent

“…Any remedy for rendering antimicrobial properties to these surfaces is desired to present no systemic or localized toxicity, inhibit the proliferation of most species of microbial cells in contrast to a selected category of species, provide a robust system enabling ease-of-use, and involve a low production cost [5]. In this respect, silver coatings have been good candidates [6][7][8], thanks to their broad-spectrum antimicrobial activity through mechanisms such as production of reactive oxygen species (ROS) [9]. However, this approach is associated with drawbacks such as incompatibility of the conventional coating techniques with some important solids, altering the structure of surface, and corrosion with elution of silver ions, which ironically are the agent of antimicrobial activity [10].…”

Silver Nanoparticles and Chitosan Oligomers Composites as Poplar Wood Protective Treatments against Wood-Decay Fungi and Termites

“…In contrast to copper-based NPs or nanocomposites, AgNPs exhibit a more versatile antimicrobial application across diverse biological agents and disciplinary fields, showcasing efficacy on various materials and in different application formats [25]. Additionally, they demonstrate superior protective efficacy over time and at varying concentrations, although outcomes at lower concentrations may vary due to factors such as size, shape, application methods, and resistance to leaching [18,[26][27][28][29][30]. Furthermore, the use of silver nanoparticles does not interfere with the deposition process or introduce defects in wood paint, offering a distinct advantage over copper nanoparticles that may potentially introduce harmful residues and defects [26].…”

“…Additionally, they demonstrate superior protective efficacy over time and at varying concentrations, although outcomes at lower concentrations may vary due to factors such as size, shape, application methods, and resistance to leaching [18,[26][27][28][29][30]. Furthermore, the use of silver nanoparticles does not interfere with the deposition process or introduce defects in wood paint, offering a distinct advantage over copper nanoparticles that may potentially introduce harmful residues and defects [26]. Concerning zinc-based NPs or nanocomposites, although some studies underscore their effectiveness as a biocide, additional research is essential to fully comprehend their potential advantages and limitations, as well as the underlying mechanisms governing their protective capabilities [31].…”