Effect of pulsed current densities on co-electrodeposition of graphene oxide/ calcium-phosphate coatings and their biocompatibility

Abstract

In this study, calcium-phosphate (Ca-P) and graphene oxide (GO)/ calcium-phosphate (Ca-P) coatings were electrodeposited with different pulsed current densities on TiO2 nanotubes. Results showed that the co-electrodeposition rate in the presence of GO, especially at low current densities of 2 and 5 mA/cm2, significantly decreased. This might be due to the large size of GO sheets as compared to the size of calcium and phosphate ions. The SEM micrographs revealed that the surface of the anodized titanium could not be completely covered with the GO/Ca-P coatings applied at such low current densities. However, producing a considerable amount of H2 gases at higher current densities of 10 and 15 mA/cm2 caused the formation of a coating with poor quality. Regarding this, increasing the off part of the pulsed current by changing duty cycle from 0.3 to 0.1 led to the co-electrodeposition of GO/Ca-P coating with an acceptable quality. The FTIR and micro-Raman analyses also demonstrated that the current density of 15 mA/cm2 was more favorable to apply the coating predominantly consisting of hydroxyapatite (HA) phase. At last, studying the ability of apatite mineralization in simulated body fluid (SBF) displayed that both Ca-P and GO/Ca-P coatings electrodeposited at the current density of 15 mA/cm2 and duty cycle of 0.1 are acceptable for biomedical applications.