Biological properties of titanium
Titanium is, indeed, a relatively abundant element with a number of industrial and biomedical applications. Titanium compounds are generally poorly soluble and poorly bioavailable; thus toxicology of titanium essentiall deals with the local effects of orthopedic titanium implants (Takamura et al., 1994) and with lung damage caused by titanium dioxide particles (Baggs et al.,1997). Very limited data exist on the biological effects and the toxicity of soluble titanium(IV) complexes. In our opinion, however, this topic deserves particular attention, given the growing use of titanium implants in medicine and the possible release of soluble titanium species in vivo. In the latter case it is likely that transferrin may act as a specific carrier of this metal ion and mayplay a central role in the transport and biodistribution of soluble titanium species throughout the organism (Ishiwata et al., 1991).