Predicción termodinámica de la adhesión de Staphylococcus aureus en nanopelículas de TiO2

JONATHAN M. SCHUSTER; MARÍA L. VERA; MARIO R. ROSENBERGER; CARLOS E. SCHVEZOV

Santa Fé

Congreso; Congreso Internacional De Metalurgia y Materiales. Sam ? Conamet / Iberomat / Materia 2014; 2014

The adhesion of bacteria to the surface of an implanted prosthesis is the first step in the pathogenesis of infections associated to surgical implants. The mechanisms by which these infections occur are still unclear; adhered bacteria may remain in the surface for a long time until the environment allows them to grow (e.g., by decreasing of immunological activity) causing infection. Staphylococcus aureus produces many of the infections in surgical implants, this adheres to the implant surface forming three-dimensional structures called biofilms that promotes the adhesion of more cells and protect them from antibiotics. The process of bacterial adhesion to surfaces have a first reversible stage where the interaction is mainly physicochemical and a late irreversible stage where the interaction is mainly of molecular and cellular order. In this work the initial stage in the interaction between the S. aureus and TiO2 films synthesized by anodic oxidation is studied using a thermodynamic model. The free energy of the interaction (ΔGBSA) between S. aureus (B) and substrate (S) immersed in water (A) is calculated using the values of surface free energy (ELS) of the components. If ΔGBSA0 the process is disfavored. The ELS of the TiO2 nanofilms and pyrolytic carbon were measured by the sessile drop method using the Lifshitz-van der Waals/Acid-Base model. The ELS of the S. aureus was taken from the literature. It was found that the adhesion of the S. aureus is thermodynamically favored in only one of the nanofilms (S1-V70) which is crystalline with the anatase structure. Besides, it was observed that the coating that contain rutile are the less favored thermodynamically for the adhesion of this bacterium.