Surface modification of magnesium-based orthopaedic implants by AL203 Plasma Immersion Ion Implantation (PIII)

Abstract

Metallic implants are commonly applied for fracture fixation. One desirable characteristic of an implant is its ability to be degraded after bone healing, thus implants made from degradable metals, including magnesium-based alloys, may substitute conventionally used metals. However, problems associated with use of magnesium alloys include its rapid corrosion and hydrogen gas release. Surface modification may be used to solve these problems. Our group has recently applied an Al2O3 layer using PIII technology onto magnesium alloy to enhance its corrosion resistance. This study aims to investigate the corrosion resistance and biocompatibility of the Al2O3 plasma-treated magnesium alloy. To evaluate the corrosion resistance properties of the plasma-treated magnesium alloy, the immersion test using DMEM medium was conducted at 37ºC for 1 and 3 day(s). Green fluorescent protein osteoblasts (GFPOB) were cultured on plasma-treated and untreated samples for 1 and 3 day(s) to evaluate their cell attachment and proliferation. Gas bubbles were observed on day 1 on the untreated sample where the medium changed from red to purple on day 3, indicating that vigorous corrosion had occurred. No gas bubbles or colour change of the medium was observed for the Al2O3 plasma-treated sample. This suggested that the Al2O3 layer was able to improve the corrosion resistance of the magnesium alloy. The GFPOBs grew on the plasma-treated sample but not the untreated sample, which indicated good biocompatibility with the plasma-treated sample. Future mechanical property studies during corrosion are required for further validation of this material for clinical use.