RESUMO
The anchorage failure of titanium implants in human body is mainly due to biointegration problem. The proposed solution is to graft a bioactive polymer at the surface of the implant in order to improve and control the interactions with the living system. In this paper, we describe the grafting of poly sodium styrene sulfonate on titanium surface by using a silanization reaction. The key point is to increase the TiOH content at the surface of the implant which can react with methoxy silane groups of 3-methacryloxypropyltrimethoxysilane (MPS). Two procedures were used: chemical oxidation and electrochemical oxidation. The last oxidation procedure was carried out in two different electrolytes: oxalic acid and methanol. These different oxidation methods allow controlling the roughness and the depth of the oxide layer. The methacryloyl group of MPS grafted at the titanium surface by silanization reaction is copolymerized with sodium styrene sulfonate using a thermal initiator able to produce radicals by heating. Colorimetric method, ATR-FTIR, XPS techniques and contact angle measurements were applied to characterize the surfaces. MG63 osteoblastic cell response was studied on polished, oxidized and grafted titanium samples. Cell adhesion, Alkaline Phosphatase activity and calcium nodules formation were significantly enhanced on grafted titanium surfaces compared to un-modified surfaces.
Assuntos
Materiais Revestidos Biocompatíveis/química , Galvanoplastia/métodos , Osteoblastos/fisiologia , Polímeros/química , Ácidos Sulfônicos/química , Engenharia Tecidual/métodos , Titânio/química , Adesão Celular/fisiologia , Técnicas de Cultura de Células/métodos , Linhagem Celular , Proliferação de Células , Sobrevivência Celular , Cristalização/métodos , Humanos , Teste de Materiais , Osteoblastos/citologia , Oxirredução , Propriedades de SuperfícieRESUMO
Integration of titanium implants into bone is only passive and the resulting fixation is mainly mechanical in nature, with anchorage failure. Our objective, to increase the biointegration of the implant and the bone tissue, could be obtained by grafting a bioactive ionic polymer to the surface of the titanium by a covalent bond. In this paper, we report the grafting of an ionic polymer model poly(sodium styrene sulfonate) (polyNaSS), in a two-step reaction procedure. Treatment of the titanium surface by a mixture of sulfuric acid and hydrogen peroxide allows the formation of titanium hydroxide and titanium peroxide. In the second reaction step, heating of a metal implant, placed in a concentrated solution of sodium styrene sulfonate monomer (NaSS), induces the decomposition of titanium peroxides with the formation of radicals capable of initiating the polymerization of NaSS. Various parameters, such as temperature of polymerization and time of polymerization, were studied in order to optimize the yield of polyNaSS grafting. Colorimetry, Fourier-transformed infrared spectra recorded in an attenuated total reflection, X-ray photoelectron spectroscopy techniques and contact angle measurements were applied to characterize the surfaces. MG63 osteoblastic cell response was studied on polished, oxidized and grafted titanium samples. Cell adhesion, alkaline phosphatase activity and calcium nodules formation were significantly enhanced on grafted titanium samples compared to unmodified surfaces.