ANTIBACTERIAL AND HIGH DURABLE ALUMINIUM OXIDE LAYER ADDITIVATED WITH SILVER NITRATE

The emergence and spread of the SARS-CoV-2 pandemic has driven the focus of the scientific community on a critical issue: the development of antimicrobial surfaces for public areas that do not necessitate the substantial use of chemicals for disinfection processes. In this regard, silver is one of the most commonly employed elements, due to its high biocidal activity. This study describes an easy approach for manufacturing aluminium anodize layers with antimicrobical properties, achieved through co-deposition with silver nitrate. The durability of the samples and their resistance to chemicals were assessed employing multiple accelerated degradation tests, including the exposure in the salt spray, climatic, UV-B and Kesternich chambers, evaluating the contact with synthetic sweat, and using the scrub test, emphasizing the low impact of silver in affecting the protective behavior of the alumina layers. In addition, the ISO 22196: 2011 standard was adopted as a reference protocol to develop a method for determining the actual antibacterial activity of the composite layers against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Moreover, as evidenced by Trypan blue flow cytometry analysis and microscopy observations, the composite layers did not exhibit significant cytotoxicity activity, allowing this material to be used in applications in close interaction with humans. Lastly, the samples demonstrated excellent antibacterial efficiency even after the chemical-physical degradation processes, guaranteeing the antimicrobial surfaces' long-term durability. In summary, this work presents a straightforward method for producing anodized aluminum surfaces with superior antibacterial performance.