Enhancing corrosion resistance and bioactive behavior of porous metallic scaffolds through electrochemical coatings

Abstract

The percentage and size of the pores obtained by conventional powder metallurgy route, as well as corrosion phenomena and poor bioactivity, limit the clinical success of porous metallic implants. In this work, a joint solution is proposed, combining the manufacture of bone implants by the loose sintering technique (economical, repetitive and maximized porosity), coated with chitosan-bioactive glass bio-composites synthesized by chronoamperometry and electrophoresis techniques. The influence of porosity on the biomechanical and biofunctional behavior of titanium substrates is evaluated, as well as the role of bioactive coatings in improving their corrosion resistance and osteoinduction capacity. These electrochemical methods are optimized and presented as a promising strategy for developing uniform protective coatings. Biodegradable coatings based on chitosan are replaced by calcium phosphates that form on the surface of the implants, promoted by the effect of bioactive glass reinforcements (BG-45S5 and BG-1393). Chitosan-bioactive glass composite coatings significantly improved the corrosion resistance of titanium substrates. Loose sintering samples exhibited a 94 % reduction in corrosion current density reaching 1.08·10–6 A/cm2 and a polarization resistance of 14·103 Ω/cm2 with BG-1393. The in vitro bioactivity study confirmed apatite formation after immersion in SBF, with a Ca/P ratio close to natural hydroxyapatite (1.67), particularly for chitosan with BG-45S5 (achieving 1.76).