Enhanced mechanical properties and biocompatibility of Mg-Gd-Ca alloy by laser surface processing

Surface properties are a key determinant of the cell's response to implants. In this paper, we present a hybrid laser surface modification method including melting and surface texturing on Mg-Gd-Ca alloy to improve mechanical properties and control cell behavior. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM) were used to investigate the microstructure evolution and surface morphology. Mechanical properties were studied by nanoindentation and tribometer. In vitro adhesion and growth behavior were studied using MC3T3-E1 cells. Results showed that the laser surface modification can improve the hardness and wear resistance without deteriorating elastic modulus of Mg-Gd-Ca alloy. On the laser melted & LIPSS surface, the cells were elongated along the direction of LIPSS, due to the anisotropic and persistent mechanical stimulus effect. While on the laser melted & micro-groove surface, the cells exclusively attach to the laser melted surfaces and completely avoid the surrounding the micro-groove, due to the cell-repellent effect of the microstructures. We propose that the enhanced mechanical properties and biocompatibility accompanied with the simplicity of fabrication makes laser surface modification a promising candidate method for biomedical applications in biomedical devices.