Laser surface modification of Mg-Gd-Ca alloy for corrosion resistance and biocompatibility enhancement

Magnesium alloy has attracted much attention as biodegradable material for medical devices including implants and stents in recent years. However, poor corrosion resistance is the main problem to limit practical applications because high degradation rate will cause fast increase in pH, while the large release of ions into the medium can lead to cytotoxicity. In this work, we demonstrate the capability of laser surface modification for better corrosion resistance of Mg-Gd-Ca alloy to avoid rapid degradation, which helps to enhance the biocompatibility. Microstructure of both as-received surface and laser-modified surface were analyzed carefully by Scanning Electron Microscopy and X-ray Diffraction. Electrochemical corrosion behavior and immersion test was investigated in order to examine the degradable behavior of laser-modified Mg-Gd-Ca alloy. The enhanced corrosion resistance was found to be caused by the combined effect of the dissolution of secondary phase and the decrease of galvanic corrosion in the laser-modified zone. Moreover, results of direct cell culturing suggested that the laser-modified surface exhibited good cell adhesion property, spreading performance and proliferation capacity.