Ultraviolet irradiation assisted liquid phase deposited titanium dioxide (TiO2)-incorporated into phytic acid coating on magnesium for slowing-down biodegradation and improving osteo-compatibility.

It remains challenging to build up a multifunctional coating onto biodegradable magnesium (Mg) for biomedical use. In this study, a small amount of titanium dioxide (TiO2) has been incorporated in situ into phytic acid (PA) coating when it was chemically deposited on Mg substrate targeted to biodegradable implant applications. Ultraviolet (UV) irradiation was utilized in the liquid phase deposition of TiO2 to improve the quality of coating (PA&TiO2-UV). This PA&TiO2-UV coating was compact, thicker and more hydrophilic compared with sole PA or TiO2 coating. The PA&TiO2-UV coated Mg presented a seven times lower electrochemical corrosion current density as well as significantly slower in vitro degradation rate up to 500 h in phosphate buffer saline as compared to the direct PA coated Mg. In addition, the UV irradiation showed remarkably to promote the MC3T3-E1 pre-osteoblast cells adhesion and proliferation especially after 7 days of culture. Further, the PA&TiO2-UV coating adhered more firmly on Mg substrate after 90° bending than the other coatings, indicating a better mechanical compliance on Mg substrate. These results make this PA&TiO2-UV complex coating bodes well for biodegradation slowing-down, osteo-compatible as well as mechanical compliant modification of Mg for orthopedic implants applications.