03 mars 2011
CELLS UNDER TiO2 CREAM

A cell that has internalized TiO2 nanoparticles. These accumulate in vesicles of the cytoplasm and sometimes reach the nucleus.

The impact of nanoparticles on health is a burning question for the general public. Teams from the SCIB and IRAMIS/SPAM have studied the damage caused to cultured human cells by nanoparticles of titanium dioxide, used in sunscreens and in paints.

 

The toxicity of nanoparticles is not related to the chemical nature of the materials they are made of, which are very classical, but rather to their extreme state of division that gives them a potentially novel surface reactivity. The determination of the intrinsic toxic properties of nanomaterials has a strong implication: they must stay in this size range for the entire duration of the experiment. Using ultrasounds to disperse nanoparticles of controlled size and shape, we have limited their aggregation and created more reproducible experimental conditions than those of a number of published works.

 

A nanoparticle is toxic only if it enters the cell. To study this parameter, we incubated cells in the presence of TiO2 nanoparticles. We observed by electron microscopy and analyzed by synchrotron-based techniques that nanoparticles may go through the cell membrane and even reach the nucleus. Is there then a risk of inducing DNA damage? Yes, free radicals are produced in the presence of nanoparticles and induce strand breaks and oxidized bases. The presence of nanoparticles also strongly decreases the DNA repair capacities, which makes the phenomenon worse. Thus, when they are isolated, and if the cells themselves are isolated, TiO2 nanoparticles have a genotoxic potential. It now remains to be evaluated how the natural barriers of the organism (skin, mucous membranes) in an environment conducive to the aggregation of particles (salts, proteins …) decrease the direct contact with cells and limit the toxicity observed in these model experiments.

 

Further reading: Jugan ML et al., Journal of Biomedical Nanotechnology 7 (2011) 22-23

 

Maj : 17/02/2014 (934)

 

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