This study aims to develop tantalum oxide (Ta2O5) films onto commercially-pure titanium (cp-Ti) surface using magnetron sputtering deposition and to evaluate its electrochemical behavior, biocompatibility and biofilm formation. Cp-Ti discs will be divided into groups: machined (surface I - control) and treated with Ta2O5 films (surface II - experimental). In the electrochemical assay, standard tests such as open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic tests will be conducted in simulated body fluid solution (pH 7.4) An appropriate electrical circuit will be used to determine the capacitance (Cdl) and polarization resistance (Rp) of the oxide layer. The Tafel's method will be used to ascertain the corrosion current density (Icorr) and corrosion potential (Ecorr). The passivation current density (Ipass) will be the amount of current in the transition between the active and passive region in the polarization curve. Discs' topography will be characterized by the scanning electron microscopy (SEM), energy dispersive spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction analysis, perfilometry and surface free energy. For biological tests, murine osteoprogenitor cell line (MC3T3E1) will be used. The structure and cell morphology will be evaluated by SEM and fluorescence microscopy. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) will be used to check the levels of osteogenic genes expression. MTT assay will be used to assess cell viability. Alizarin test will be performed to identify and quantify the mineral deposits in the cells. The immersion of the samples in body fluid will be conducted to test the bioactivity of the surfaces. For microbiological test, the biofilm composed of Streptococcus sanguinis will formed onto the surface of the discs. The log of colony forming units will be determined (log CFU) and structural biofilm analysis will be performed by SEM. Quantitative data will be submitted to the most appropriate statistical analysis with 5% significance level. The number of specimens for each test will be determined after the pilot study.
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