In vitro bioactivity and electrochemical characterization of surface modified titanium and its alloys for biomedical applications

Abstract

Titanium and its alloys are ideal materials for orthopedic implants. However, it remains a challenge to promote biointegration of these implants, which is essential for its long life and function within the body. The success of titanium based materials in these applications is due to their excellent mechanical properties, high corrosion resistance and good biocompatibility. However, the plasma-spray technique does not permit accurate control of the chemical composition, crystallographic structure, and crystallinity of the coating. Other methods like electrophoretic and electrochemical deposition, were carried out at an elevated temperature, which may cause decomposition of the hydroxyapatite coating and deterioration of the metallic substrates. Mechanical methods for surface treatments involve removal of surface material by cutting and abrasive action. Chemical methods are based mainly on chemical reactions occurring at the interface between titanium and an electrolyte. Chemical treatments of titanium surfaces proposed so far are primarily aimed at controlling the formation of titania or sodium titanates on the titanium substrates that induce apatite formation when those substrates are soaked in simulated body fluid (SBF) solution. In the present investigation, the commercially pure titanium (and#945;), Ti-15Mo (ß) and Ti-5Al-2Nb-1Ta (and#945;+ß) alloys were studied. The primary research was focused on surface modification of titanium and its alloys by simple chemical treatment using mixture of alkali and hydrogen peroxide, alkali treatment followed by subsequent heat treatment in order to improve the biocompatibility and corrosion resistance in the SBF solution. The electrochemical impedance spectroscopic measurements revealed the two time constant behavior, indicating the inner barrier and outer porous layer for the immediate immersion in SBF solution whereas the appearance of third time constant at high frequency region revealed the resistance provided by the formed apatite layer after 7 days of immersion in SBF solution. newline newline