Optimizing anodization processing parameters for improved properties of nanostructured oxide surfaces on magnesium alloys for antimicrobial implants

This article reports the optimization of anodization parameters to create homogeneous nanostructured oxide layers on magnesium (Mg)-2 wt% zinc (Zn)-0.5 wt% calcium (Ca) (designated as ZC21), Mg-4 wt% Zn-1 wt% strontium (Sr) (designated as ZSr41), and pure Mg pins. The ZC21 alloy anodized at 1.9 V, ZSr41 alloy anodized at 1.8 V, and pure Mg anodized at 1.8 V showed significantly lower corrosion current densities in revised simulated body fluid (r-SBF), and fewer bacteria, specifically methicillin-resistant staphylococcus aureus (MRSA), adhered on their surfaces in vitro. The soluble degradation products released from the anodized ZC21, ZSr41 and pure Mg pins did not affect the adhesion and morphology of bone marrow-derived mesenchymal stem cells (BMSCs) under indirect contact condition, but the cell adhesion and spreading on their surfaces were lower when compared with those of Ti pin control and glass reference. This systematic in-depth investigation revealed the effects of processing parameters on their surface microstructure and properties, corrosion properties, and in vitro degradation and biological properties of ZC21, ZSr41 and Mg pins in the respective cultures of BMSCs and MRSA. The anodized ZC21, ZSr41 and Mg pins demonstrated their potential for biomedical applications and should be further studied in vivo toward clinical applications.