REVESTIMENTOS A BASE DE FOSFATO DE CÁLCIO E HIDROXIAPATITA IMPREGNADOS POR ZIRCÔNIA PARA PRÓTESES ORTOPÉDICAS

• Autor(a) principal: Severo, Vinícius de Ávila
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional Universidade Franciscana
• Texto Completo: http://www.tede.universidadefranciscana.edu.br:8080/handle/UFN-BDTD/807
• topic: Nanorevestimentos; biocompatibilidade; filmes finos.; Nanocoating; biocompatibility; thin films.; Nanociências

Metallic materials for biomedical applications have been extensively studied in recent years by many researchers, mainly for technological applications in the areas of health and clinical applications, with the aim of replacing or repairing bone tissues in orthopedic surgeries. Problems such as the release of metal ions, bone resorption, inflammatory processes and pain symptoms have been reported in several cases. Even the development of new classes of materials has not been able to overcome all the mentioned disadvantages. The complete understanding of the interface between biomedical material, bone tissues and body fluids is the main challenge for a long-term use of biomedical devices without any adverse symptoms. The purpose of this work is the development of a surface coating for orthopedic prostheses by the deposition of nanostructured thin films based on hydroxyapatite (HA) and calcium phosphates reinforced by zirconium oxide nanoparticles. These coatings aim to improve the chemical stability of the human tissue/prosthesis interface, providing better biocompatibility and bioactivity of the medical devices, with consequent increase in equipment long-term use. These coatings will be produced by combining three deposition techniques of surface coatings: anodization, sol-gel and physical vapor deposition (PVD). The coatings were structured with a first layer of titanium dioxide deposited on the surface of cp-Ti (substrate) by the anodizing technique. Subsequently, phosphate films with varying contents of zirconium acetylacetonate (0, 3, 5 and 7 g) were deposited by sol-gel and PVD techniques (using HA targets with zirconium oxide). The TiO2 barrier films deposited by electrochemical process showed very satisfactory stability results, forming a natural barrier to the ionic flow of the substrate base material to adjacent tissues. The variation of the resting potential in the films with TiO2 was 0.155 V 1.14 V for a time of 18000 s in Ringer's solution, indicating excellent chemical stability of the coating. The addition of a hydroxyapatite film on the surface of titanium substrates previously coated by porous TiO2 layer shifted the potential to positive values indicating high film stability. The addition of zirconium oxide to the hydroxyapatite film increased the chemical stability of titanium. The calcium phosphate films showed, for certain deposition situations, the formation of hydroxyapatite on the surface of the sample. These coatings showed good results for cell adhesion and viability. All films presented cell viability greater than 95%, the films deposited by both techniques (sol-gel and PVD) without addition of acZr presented 100% cell viability. Cell adhesion increased as compared to the negative control as the zirconium content increased percentage in the composition of the film. Even in samples with pure hydroxyapatite (0 g acZr), cell adhesion was better compared to the negative control.