Novel Hydrophobic Nanostructured Antibacterial Coatings for Metallic Surface Protection

Abstract

A simple and cost-efficient method to modify different surfaces in order to improve their bioactivity, corrosion and wear resistance proved to be sol-gel coatings. The silane layers have been shown to be effective in the protection of steel, aluminum or magnesium alloys and copper and copper alloys. Moreover, it has been found that the adding of different inorganic nanoparticles into silica films leads to increasing their performance regarding corrosion protection. In this study, we fabricated, a simple sol-gel method, transparent mono- and bi-layered hydrophobic coatings with simultaneous antibacterial, hydrophobic and anti-corrosive properties for the protection of metallic surfaces against the action of air pollutants or from biological attacks of pathogens. The first layer (the base) of the coating contains silver (Ag) or zinc oxide (ZnO) nanoparticles with an antibacterial effect. The second layer includes zinc oxide nanoparticles with flower-like morphology to increase the hydrophobicity of the coating and to improve corrosion-resistant properties. The second layer of the coating contains a fluorinated silica derivative, 1H,1H,2H,2H-perfluorooctyl triethoxysilane (PFOTES), which contributes to the hydrophobic properties of the final coating by means of its hydrophobic groups. The mono- and bi-layered coatings with micro/nano rough structures have been applied by brushing on various substrates, including metallic surfaces (copper, brass and mild steel) and glass (microscope slides). The as-prepared coatings showed improved hydrophobic properties (water CA >90°) when compared with the untreated substrates while maintaining the transparent aspect. The corrosion resistance tests revealed significantly lower values of the corrosion rates recorded for all the protected metallic surfaces, with the lowest values being measured for the bi-layered coatings containing ZnO particles, both in the first and in the second layers of the coating. Considering the antibacterial activity, the most effective were the AOAg-II and AOZnO-II coatings, which exhibited the highest reduction of microbial growth.

Antibacterial and biofilm-inhibiting cotton fabrics decorated with copper nanoparticles grown on graphene nanosheets

“…The surface roughness of the rGO/Cu fabric was changed by the rGO sheets, and the hydroxyl and carboxyl groups of GO and cotton were removed during the reduction process by NaBH 4 31 , 32 . Surfaces with higher hydrophobicity have a stronger antibacterial effect 33 . Particularly, superhydrophobic surfaces have antibacterial adhesion properties, as they naturally possess nano/microscale structures in addition to the repulsion of water, which limits the access of bacteria on the surface 34 , 35 .…”

Progress in Nanostructured Mechano-Bactericidal Polymeric Surfaces for Biomedical Applications

“…This phenomenon is not a bactericidal activity, but it uses the non-adhesion mechanism resulting in a reduction in viability of the bacteria on the surface. There were many researchers who investigated the effect of surface wettability (hydrophobicity [154,[215][216][217][218] or hydrophilicity [216,219,220]) on the bactericidal efficacy of nanostructured surfaces. Valiei et al studied the mechano-bactericidal efficacy of etched silicon nanopillars against P. aeruginosa bacteria.…”

ZnO-based antimicrobial coatings for biomedical applications

“…Recent study showed that sol–gel coating technique can be used to coat metallic substrates containing monodispersed nanoparticles of Ag and Zn (sizes are in the range of 100–150 nm) with flower-like ZnO nanostructures. The rough surface texture of ZnO obtained from the sol–gel coating method displayed a superior hydrophobicity and liquid repellant properties to minimize biofilm formation [ 157 ]. The tribological and electrochemical behavior are another crucial factor in ZnO coating.…”