Determination of synergistic effect between roughness and surface chemistry on cell adhesion of a multilayer Si- Hydroxyapatite coating on Ti6Al4V obtained by magnetron sputtering

Abstract

[EN] Ti alloys are widely used in the biomedical field because they have an adequate balance between mechanical properties, corrosion resistance and biocompatibility. However, when this material is incorporated in the human body, unfavorable reactions can be obtained which do not allow a good osseointegration due to the formation of a fibrous and non-adherent layer between the biomaterial and the bone, which can lead to failure or rejection of the implant. In this study, the influence of surface modification of Ti6Al4V alloy with a hydroxyapatite (HA) and silicon (Si) coating on its biological response in vitro was evaluated. The deposition process was performed by sputtering on two Ti6Al4V surfaces with different root mean square roughness values, the first one with 3.8 nm and the second one with 48.7 nm. The surface morphology of the coatings was observed by Scanning Electron Microscopy and Atomic Force Microscopy, the chemical composition was evaluated by X-ray Energy Dispersive Spectrometry and micro-Raman Spectroscopy. The in vitro biological response of the coatings was evaluated by cell metabolic activity assay and cell adhesion tests, using mouse mesenchymal stem cells. The control of the process parameters allowed obtaining a multilayer HA-Si coating with good compositional balance (Ca/P ratio very close to 1.67 and characteristic vibrations of the HA phase). Roughness values of 27 +/- 5 nm and 52 +/- 6 nm were obtained for the multilayer coatings obtained on Ti6Al4V (smooth surface) and Ti6Al4V (rough surface), respectively. Biological assays indicated a potentially non-toxic character of the coatings, moreover, the cell adhesion of Ti6Al4V was favored both by the incorporation of the HA-Si multilayer coating and by the increase in the roughness of the substrate.