Coating of Ti-6Al-4V alloy with pure titanium film by sputter-deposition for improving biocompatibility

Coating of Ti-6Al-4V alloy substrates with pure titanium film by magnetron d.c sputtering in Ar gas was examined in order to improve the biocompatibility of the alloy, because a pure titanium barrier layer prevents harmful substances such as aluminum or vanadium from leaching into biological tissues. The effects of the pure titanium barrier layer on the cytocompatibility of the titanium alloy were investigated. Under visual observation, the pure titanium film appeared to be uniform and adhesive. Under SEM, the surface of the deposited pure titanium film was observed to consist of fine accumulating and aggregating particles. According to the Auger electron spectroscopy (AES) depth-profiles of Ti and Al for the deposited titanium film and Ti-6Al-4V alloy substrate, it was confirmed that no aluminum atoms diffused to the film surface from the alloy substrate. Thus, it was expected that the obtained titanium film could improve the biocompatibility of the alloy as a barrier layer, which prevents aluminum atoms from leaching into biological tissues. On the basis of the results of the in vitro cytotoxicity test, it was found that the viability, i.e. the ratio of living cells to the sum of living cells and dead cells, was higher for the titanium film than for the alloy. Therefore, the deposited titanium film exhibited better cytocompatibility than the Ti-6Al-4V alloy, leading to the conclusion that the cytocompatibility of the alloy was improved by coating it with the titanium film. Copyright (C) 2006 John Wiley & Sons, Ltd.