Biocompatibility of surface modified Nickel-Titanium shape memory alloy with osteoblasts cultured in vitro

BACKGROUND: Although shape memory alloy has been extensively used in modern medicine, including orthopaedics and dental surgery, the body fluid could influence the stability of biomaterial and some ions released by materials may cause toxic and side effect to human body. The technology for the modification of shape-memory materials is of crucial importance for clinical use of shape memory alloy. OBJECTIVE: To investigate the biocompatibility of diamond-like carbon (DLC) coated Nickel-Titanium shape memory alloy and uncoated shape memory alloy with osteoblasts cultured in vitro. DESIGN, TIME AND SETTING: A comparative observation. The study was performed at the Institute of Othopaedics of Lanzhou University from March to June 2005. MATERIALS: A total of 30 DLC-coated Nickel-Titanium shape memory alloy disks, 6 mmx7 mmx0.5 mm, and the same amount of uncoated ones of equal size were provided by College of Materials, Lanzhou University. METHODS: Rabbit osteoblast suspension of the third passage at density of 10x10 super(8)/L were incubated with DLC-coated Nickel-Titanium shape memory alloy disks and uncoated shape memory alloy in 12-well culture plate in 5% CO sub(2) at 37 degree C. MAIN OUTCOME MEASURES: Culture media were counted at 1, 2, 3, 4 and 5 days of culture to determine alkaline phosphatase (AKP) activity and nickel (Ni super(2+)) concentration. RESULTS: The proliferation of osteoblasts and the concentration of AKP in DLC- coated group were greater than uncoated group; while the uncoated group released more Ni super(2+) into the cells culture media than coated group (P < 0.05). CONCLUSION: DLC-coated Nickel-Titanium shape memory alloy appears to have better biocompatibility with osteoblast cultured in vitro compared to uncoated ones.