Cytocompatibility evaluation of surface modified Ni-Ti shape memory alloy using the MTT assay

The cytocompatibility of N⁺ ion implanted and shot peen surface amorphised Ni-Ti shape memory alloy has been evaluated using the MTT cytotoxicity assay over 48 hours of 3T3 fibroblast contact and growth. In addition, SEM morphological examination and wetting behaviour measurements with full culture media were made. The modified Ni-Ti surfaces did not induce a cytotoxic response over the examination period and the SEM direct observation showed normal morphologies of cells grown upon the Ni-Ti surfaces. These results indicate that the adherent Ti-O₂ rich surface film present on unmodified Ni-Ti is preserved during surface modification. Furthermore, the ion implanted surfaces showed enhanced cellular attachment, which is speculated to be a consequence of modified surface charge distribution.