H. Aihara, B. Chun, K. Jaladi, A. M. -. C. Kuo, G. S. Selvaduray, San Jose State University, San Jose, CA; A. Y. Craig, Evans Analytical Group, Sunnyvale, CA
Microblasting, similar to sand blasting, involves the use of high pressure and abrasive powders to remove quantities of surface layers. This research focused on investigating the effect microblasting of NiTi, with Al203 abrasives, would have on its cytocompatibility. The test specimens were weighed before and after microblasting to determine material removal, if any. Surface morphology changes were characterized by Scanning Electron Microscopy (SEM), surface roughness effects were quantified by Atomic Force Microscopy (AFM), and contact angles changes were measured by the sessile drop method. The effect of microblasting on the cytotoxicity of the specimens was determined following the method outlined in ISO 10993-5. The amount of material removed was found to increase with increasing particle size of the abrasive and microblasting pressure. The surface roughness was also found to increase with increasing particle size of the abrasive. However, the contact angle with DI water was found to be not affected by the microblasting parameters. There was no significant change in the cytocompatibility of the specimens, regardless of microblasting conditions. However, the surface was found to contain Al, presumably from the Al203 abrasive used. The detailed chemical nature of this deposit is currently being investigated by X-ray Photoelectron Spectroscopy.
Summary: The current research is undertaken to investigate the effect of microblasting on NiTi alloy by using various sizes of aluminum oxide particles under three different pressures. The surface roughness was quantified by AFM and the surface was characterized by SEM. Sessile drop method was used to measure the contact angles. A cytotoxicity test was conducted to assess the toxicity of NiTi alloy in HEp 2 cell culture. The surface was found to contain Al after microblasting. We are investigating the surfaces by XPS and depth profile analysis to delineate the nature of the Al deposit.
