Estudo da ação bactericida em regiões próximas à superfície de titânio e AISI 304 pela incorporação de prata

Abstract

Contamination by bacterial biofilms has a strong negative impact, especially when given on the surface of prostheses, implants, pins and other medical-surgical devices. In this study metal samples of Titanium cp and AISI 304 were produced with Ag+ ions implanted by IPD at different energies: 2 and 4 keV and different implantation times: 30, 45, 60 and 90 min to obtain surfaces with bactericidal properties. The depth and the distribution profile of the implanted ions were estimated by Monte Carlo simulation using the SRIM 2008 software. The Ag+ ions concentration incorporated in the samples was determinate by spectroscopic techniques. Bactericidal activity of the titanium samples with different concentration of Ag+ ions was evaluated by the treatment of a liquid industrial waste. It was submitted to Escherichia coli counting before and after the contact of the waste with the samples. The contact angle was measured to evaluate the wettability of the titanium samples that presented the highest silver concentration. Wettability is a determinant factor in the adhesion of bacteria and human cells. Cytotoxicity was evaluated by cell viability test and morphological analysis. A 27% reduction of E. coli in the industrial waste treated with the sample implanted at 4 keV was achieved for 45 min with an initial concentration of 3.35 × 1015 atoms cm2. No toxic effect of silver was detected on human MG63 cells, even considering the higher concentration of silver, since there was no reduction in cell adhesion and proliferation c to untreated titanium. For the AISI 304 samples, the microbial adhesion assays were performed for the bacteria Listeria monocytogenes and Salmonella Enteritidis, resulting in a reduction of 65.9 and 69.8%, respectively. Finally, the results showed that the treatment studied to obtain metallic materials with bactericidal action is promising for applications in the medical field, however a long term evaluation is necessary to guarantee the safety of its use.