Titanium Surface Chemical Composition Interferes in the Pseudomonas aeruginosa Biofilm Formation.

Bacterial adhesion on three different surfaces: untreated Ti, plasma nitriding, and plasma carbonitriding Ti substrates were investigated. The samples were placed in bacterial cultures of Pseudomonas aeruginosa to assess biofilm formation. The correlation between the amount of bacteria attached to the surface after a lapse of time with nanotopography and physicochemical properties was performed. TiN showed the highest capacity to avoid bacterial adhesion, while presenting intermediate roughness and wettability. Although the surface of TiCN had the highest surface roughness and low contact angle (high wettability), bacterial adhesion was intermediate on this sample. Untreated Ti, even though presenting a smooth surface and low wettability, had the highest tendency to form biofilms.

Influence of Oxynitrided Surface in the Production of a Less Susceptible Titanium Surface to Skin-Borne Bacterial Adhesion.

There is a growing quest for an ideal biomaterial that shows appropriate cellular response and is not susceptible to microbial adhesion. In this study, commercial grade II titanium was submitted to RF/DC plasma surface modification at 2.2 mbar, using gas mixtures of argon, nitrogen, and oxygen at proportions 4:1:2 and 4:1:3. The surfaces were physically and chemically characterized. In order to evaluate bacterial response, the surfaces were exposed to Staphylococcus epidermidis. Oxynitrided samples, although having a higher roughness as compared with untreated samples, exhibited lower bacterial growth. This observation is probably due to the formation of different crystalline phases of nitrides and oxides caused by plasma treatment. The surface with highest contact angle and highest surface tension showed lower bacterial adhesion. These results were confirmed by scanning electron microscopy. The role of nitrogen in reducing bacterial adhesion is clear when this material is compared with untreated titanium, on which only an oxide film is present.

Análise da preferência celular em diferentes superfícies de Ti exposta ao mesmo meio de cultura / Analysis of the cell preference in different Ti surfaces exposed to the same culture environment

Adesão e proliferação celular em superfícies de titânio comercialmente puro (Grau II) modificadas por plasma foram analisadas seguindo duas estratégias diferentes, a saber: (1) exposição de um tipo de superfície para cada cultivo celular e (2) exposição de duas superfícies diferentes num mesmo cultivo decélulas. Observou-se diferença estatisticamente significante em relação à proliferação e morfologia,entre as amostras nitretadas e as amostras sem tratamento. Para a primeira estratégia verificou-se uma preferência celular levemente superior nas superfícies nitretadas. Entretanto, quando exposta as duas superfícies num mesmo meio de cultura (estratégia 2) verificou-se que a preferência pela parte nitretada foi muito superior àquela verificada na estratégia 1. Isto significa que em situação de concorrência entre duas superfícies (tratada e não tratada), a preferência celular é intensificada.