Double layered nanostructured composite coatings with bioactive silicate glass and polymethylmetacrylate for biomimetic implant applications

We studied the corrosion behaviour of bioactive glass–polymer nanostructured coatings of titanium implants for prostheses. The layers were deposited by MAPLE on titanium substrates of biomedical use. The potentiodynamic polarization investigations showed that the obtained samples exhibited a higher corrosion resistance as compared to bare titanium. The behaviour of coatings in contact with physiological fluids was studied in vitro by electrochemical impedance spectroscopy. The initial bioactive glass–polymer coating proved to be a good insulator. After immersion in simulated body fluid the bioactive glass dissolution and the adsorption of electrolyte ions were initiated causing the formation of an outer bioapatite protective layer. A simple cell circuit proved sufficient to describe unimmersed, short (7 days) and/or long (42 days) time immersed samples at room temperature, while after 14, 21, 28 or 35 immersion days, the use of a double cell circuit was mandatory. This was indicative for the formation of a double nanostructure consisting of an inner barrier (mainly polymer) and an outer porous (bioapatite) film with potential beneficial effects for osseointegration capacity of the Ti implants.