In biological media, proteins can rapidly adsorb on NPs surface forming the ��protein corona�� but this phenomenon is strongly dependent on NPs surface chemistry and could influence NPs internalization by cells. Indeed, Lunov et al. previously showed that internalization of PS NPs did not involve phagocytosis by human macrophages probably because of a lack of opsonizing plasma proteins. Fr?hlich et al. showed a reduced cellular IPI-504 uptake by the endothelial EAhy926 cell line due to the presence of these proteins. The NPs uptake by macrophages or epithelial cells plays a central role in biological responses such as director indirect production of reactive oxygen species. Mechanisms of cell damages such as inflammation, genotoxicity and apoptosis caused by NPs are often explained by the production of ROS. Shukla et al. recently showed on the human epidermal A431 cell line that internalized TiO2 NPs induced a significant reduction of glutathione and ROS generation in association with oxidative DNA damage and micronucleus formation. Moreover, other authors demonstrated that indirect cytotoxic effects could also occur via ROS generated by primary apoptotic intestinal Caco-2 cell line, which then induced apoptosis in neighboring cells. Even though several RGFP966 studies have reported the ability of NPs to induce DNA damages, only few studies have focused on genotoxic effects related to NPs surface chemistry. Moreover, to our knowledge, there is no published data on potential genotoxic effects of polystyrene NPs related to their surface chemistry. These NPs are widely used in nanotoxicology for studying cellular uptake because they are easily traceable by fluorescence, often synthesized in research laboratories, but also commercially available with reproducible sizes and surface chemistry and exhibiting extremely slow degradation. Moreover, polystyrene nanoparticles are commonly found in spray and exterior paints and are also used in electronics and diagnostics processes.Here, the goal was to investigate specific uptake and links with the cytotoxic effects induced by polystyrene nanobeads with distinct surface chemistry.