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

Infections acquired in public spaces (i.e., transports, restaurants, and bars, hospitals) present a serious burden for the entire healthsystems. In this respect, appropriate preventative and control measures in order to eliminate or reduce the negative effects ofsurface-transmitted infections appear highly desirable. Alongside recommendations for treatment and hygiene, antimicrobialmaterial surfaces can offer indeed an important contribution to the prevention of infections. The aim of the current paper istherefore to describe the preparation and characterization of a new material obtained by an innovative anodic oxidation, definedas 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 preparationand characterization of a new material obtained by an innovative anodic oxidation treatment applied on commercially availablealuminum alloys including the microscopic analysis and the description of the antimicrobial performances against a number ofmicroorganisms, 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 ofGHA were evaluated through experimental tests performed with a pin-on-disk tribometer. The morphology of the wear surfaceswas studied by means of a scanning electron microscope (SEM) analysis and profilometry investigations. Furthermore, in orderto evaluate the possible anticorrosive properties of GHA, tests in neutral salt spray are in addition described.