Surface-modified WE43 magnesium alloys for reduced degradation and superior biocompatibility.

Abstract

WE43 magnesium alloy was modified using surface mechanical attrition treatment (SMAT) and characterized to evaluate the influence of sub-micron surface modification on degradation rate and in vitro behavior. Modified surface was characterized for wettability, hardness, roughness, degradation rate, in vitro biocompatibility, and antibacterial activity as per the ASTM standards. The treated substrates proved to have a significant decrease in the degradation profile by creating micro pockets of oxidation channels and reducing the total delamination in comparison to the conventional heterogeneous oxide layer formed on the untreated substrate surface. Biocompatibility studies showed that this modification did not induce any toxicity to human fetal osteoblast (hFOB) cells as demonstrated by cell proliferation and enhanced calcium deposition. In fact, results showed that between the 7^th day and 14^th day of culture, there was an eight time increase in calcium deposition for the surface-treated magnesium alloy. Bacterial adhesion and toxicity studies were carried out using Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. Bacterial toxicity studies showed that both treated and control samples were toxic to the bacteria with more dead cells. Hence, this treatment has developed a highly potential orthopedic surface with decreased biodegradability rate of WE43 and simultaneously enhanced antibacterial properties with good osteoblast cell growth and calcium deposition for faster in vitro bone growth.