Surface design of c.p titanium and Ti6Al4V by plasma electrolytic oxidation (PEO) to improve biological behavior

Abstract

Event Abstract Back to Event Surface design of c.p titanium and Ti6Al4V by plasma electrolytic oxidation (PEO) to improve biological behavior Mónica Echeverry-Rendón1, 2, Oscar Galvis1, Robinson Aguirre1, Sara Maria Robledo2, Juan Guillermo Castaño1 and Felix Echeverria1 1 University of Antioquia, Centro de Investigación, Innovación y Desarrollo de Materiales (CIDEMAT)-Engineering Department, Colombia 2 University of Antioquia, Programa de Estudio y Control de Enfermedades Tropicales (PECET), Colombia Titanium is a material widely used in dental and orthopedic implants due to its mechanical and biological properties. However, modification in the material-tissue interface may improve the osseointegration process in terms of healing time and biological response[1]. As cells respond to changes in their environment by inducing a specific biological function, design of surfaces can be used for this purpose. Knowing that surface roughness at nano or micro level have a direct influence on cell behavior, the aim of this work was to study the effect on osteoblast cells of changes on morphology in surfaces of commercially pure Titanium (c.p Ti) and Ti6Al4V after anodizing. For this purpose, c.p Ti and Ti6Al4V samples were modified by Plasma Electrolytic Oxidation (PEO) at a current density of 50 mA cm-2 in 0.1 M H3PO4/1.5 M H2SO4 during 2500 s for c.p Ti and 0.1 M H3PO4/2 M H2SO4 during 390s for the alloy. After that, coatings were characterized by X-ray diffraction and scanning electron microscopy (SEM) where composition and morphology were studied. Afterwards, contact angle and surface roughness of modified and bare samples were measured. These parameters allowed to calculate the surface energy (γs) by Neuman method. In order to know the effect of the changes in morphology and consequently in wettability of the surfaces over the cells, biological assays were carried out. First at all, Cytotoxicity assay was performed by using the MTT assay. Then, human osteoblast were seeded on the top of each specimen and after 72 hours cells were fixed and observed under SEM. Adhesion test was also used to determinate changes on the osteoblast. Finally, modified samples were used to immobilize bioactive molecules such as cell adhesion peptide (RGD) and antibiotic (Gentamicine) by physical absorption. PEO treatment generates homogenous porous surfaces in which of anatase and rutile phases were found[2],[3]. Modification on the morphology of the samples showed a direct effect in the decrement on the contact angle which play an important role in cell protein adsorption and later on in the cell adhesion process. After biological evaluations, an improvement with respect to bare material was observed in modified surfaces. Non-toxicity behavior was appreciated and proper cell-cell and cell-material interactions were observed. In general, modified samples showed a better behavior when these were compared with polished surfaces. PEO is a technique that allows to control parameters such as current, voltage, time and surface chemistry with the purpose to have different surface characteristics[4]. Porous morphologies can be used to immobilize biomolecules facilitating osseointegration processes. Finally, the results of this work indicated how design of surfaces assisted by anodizing can modify in a controlled way important factors affecting the biological response of biomaterial surfaces such as topography, wettability and chemistry, which may be useful in dental and orthopedic fields. Departamento Administrativo de Ciencia, Tecnología e Innovación – COLCIENCIAS project 111556933337; Estrategia de Sostenibilidad 2014-2015 de la Universidad de Antioquia.; M.E:R is supported by PhD grant (Colciencias 567).