Gold hard anodized (GHA) materials with antimicrobial surface properties: mechanical, tribological, and microbiological characterization

Abstract

Infections acquired in public spaces (i.e., transports, restaurants, and bars, hospitals) present a serious burden for the entire health systems. In this respect, appropriate preventative and control measures in order to eliminate or reduce the negative effects of surface-transmitted infections appear highly desirable. Alongside recommendations for treatment and hygiene, antimicrobial material surfaces can offer indeed an important contribution to the prevention of infections. The aim of the current paper is therefore to describe the preparation and characterization of a new material obtained by an innovative anodic oxidation, defined as golden hard anodizing GHA. The anodic oxide surface thanks to the nanoporous structure acts as reservoir of silver ions (Ag+) which in turn confer antimicrobial properties to the material surface. Specifically, the manuscript presents a thorough preparation and characterization of a new material obtained by an innovative anodic oxidation treatment applied on commercially available aluminum alloys including the microscopic analysis and the description of the antimicrobial performances against a number of microorganisms, including among the others, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. More specifically, the current article describes some of the properties of GHA materials. The tribological properties of GHA were evaluated through experimental tests performed with a pin-on-disk tribometer. The morphology of the wear surfaces was studied by means of a scanning electron microscope (SEM) analysis and profilometry investigations. Furthermore, in order to evaluate the possible anticorrosive properties of GHA, tests in neutral salt spray are in addition described.

The effects of ultrasonic cavitation on the dissolution of lithium disilicate glass

“…Stereoscopic 3D reconstruction was conducted using the Digital Surf MountainsSEM program. This program has been used to analyze the surface morphology of many materials [38][39][40][41][42] and was suggested over AFM based on the estimated feature size of the eroded regions.…”

Antimicrobial properties dependence on the composition and architecture of copper-alumina coatings prepared by plasma electrolytic oxidation (PEO)

“…The antimicrobial activity was evaluated by comparison between the results and a controlled experiment (untreated test pieces) obtained after 24 h using Eq. ( 2) [29]:…”

“…The former strategy is recommended when anticorrosive protection is essential but diminishes the active surface area of the coating and requires additional fabrication steps. Herein, the sealing could be a disadvantage since the porous structure can act as a reservoir of antimicrobial agents [29]. The larger the surface area, the larger the number of sites available for contact killing and bacteria inactivation.…”

Electroconductive and photoactive poly(phenylenediamine)s with antioxidant and antimicrobial activities for potential photothermal therapy

“…The inoculated Petri plates were incubated at 4 1C to diffuse poly(phenylenediamine)s into the medium for 3 h, and subsequently the plates were incubated at 37 1C for 24 h. Finally, the diameter of growth inhibition zones (mm) around the wells was measured. 22,23…”