Suppression of nanoparticle cytotoxicity approaching in vivo serum concentrations: limitations of in vitro testing for nanosafety

Nanomaterials challenge paradigms of in vitro testing because unlike molecular species, biomolecules in the dispersion medium modulate their interactions with cells. Exposing cells to nanoparticles known to cause cell death, we observed cytotoxicity suppression by increasing the amount of serum in the dispersion medium towards in vivo-relevant conditions.