Toxicological and biological effects of nanomaterials

In this paper, we summarise the most recent findings on the toxicological and biological (including both favourable and adverse) effects of some studied nanomaterials (nanotubes, fallerene, metallofullerenes, their derivatives, and metallic nanoparticles). The dose-dependent, nanosize dependent, nano-structure dependent biological activity in particular nanotoxicity are discussed. Results show that some conventional methodology for assessing the biological activities of bulk materials may not be valid for nanomaterials even though they have the same chemical composition and are in mass basis. Nevertheless, this kind of research is still in its infancy, and many knowledge gaps exist that need to be filled by further studies. On the other hand, we show some intriguing examples that the adverse biological effects of nanomaterials can be reverse-utilised in biomedical fields. For instance, it was found that the 22 nm [Gd@C-82(OH)(22)], particles at a very low dose exhibit an anticancer rate of as high as similar to 60% in mice. Dose increase of 1 x 10(-7) mol/kg results in a 26% increment of anticancer efficiency. These nanoparticles have strong capacity to improve immunity and obstruct tumour invasion towards normal muscle cells but nearly without toxicity in vivo and in vitro. The fullerene derivatives with proper chemical modifications may help realise the dream of tumour chemotherapeutics of high-efficacy and low-toxicity.