Abstract: Abstract:Objective To treat the titanium alloy serface with femto-second lasers with  different energy densities,and   compare their influence  in adhesion and proliferation of osteoblasts, and to discuss the effect of  femto-second laser on the implant material surface modification. Methods Disk-like Ti-6Al-4V titanium alloy was polished and processed by femto-second lasers with different energy densities   and then  divided into low-energy group（0.07 J•cm^-2）　and high-energy group （1.40 J•cm^-2）, and the untreated disk-like Ti-6Al-4V titanium alloy   was regarded as control group; the morphology of the material surface  in  each group was observed by scanning   electron microscope. The human osteoblast-like cell line MG63 were co-cultured with different materials, the morphology of the adherent cells in  each group was observed  by scanning electron microscope, and the quantity of the adherent cells on the surface was detected  by acridine  orange staining and fluorescence microscope, and the optical density(A) value of MG63 cells was dete
rmined by methylthiazolyldiphenyl-tetrazolium bromide(MTT) colorimetric analysis, and the cell proliferation rates at different time were analyzed. Results Two
kinds of micro-morphology structure were formed on the titanium alloy surface modified by femto-second laser , one of which was  nanoscaled paralleled stripe structure and the other was micro-nano composite structure of micron-sized protrudes combined with the nanoscaled stripes structure . The amounts of the adheren cells in different groups were close at 24 h. After 48 h, the morphology of single cell on material surface in each group was not obvious, however, the cell cover area of micro-nano composite structure surface was bigger  than those  of  nanoscaled composite structure surface and the smooth surface in control group.The cell proliferation rate in high-energy group was higher than those in  low-energy group and control group(P＜0.05).  Conclusion The micro-nano composite structure on the titanium alloy surface induced  by femto-second laser can promote the  adhesion and proliferation of MG63 osteoblasts.

Key words: titanium alloy, femto-second laser, osteoblast