Improved corrosion resistance on Mg-2Ca alloy with TiO2 nanoparticles embedded in a polycaprolactone (PCL) coating

When seeking bone healing applications, calcium (Ca) is the preferred element for Magnesium (Mg) alloying. Unfortunately, the fast degradation rate of these alloys limits their applicability as bioresorbable implants. Biodegradable polymeric coatings based on polycaprolactone (PCL) were prepared to overcome this limitation. TiO2 nanoparticles (NPs) were further embedded in the polymeric matrix to increase the protectiveness and biocompatibility of such coatings. The degradation rate, assessed by electrochemical impedance technique (EIS) in cell culture medium, proved the superior protectiveness of the PCL-TiO2 coating. The corrosion layer was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In the bare and PCL coated samples, the corrosion layer was composed of brucite, carbonates, and magnesium oxychloride, whereas in the PCL-TiO2 coated sample, the additional precipitation of apatites occurred. This data advances important insights on Mg-2Ca alloys and discusses the role of bioactive coatings on the degradation of this alloy.