Exposure to TiO(2) nanoparticles increases Staphylococcus aureus infection of HeLa cells

BACKGROUND: Titanium dioxide (TiO(2)) is one of the most common nanoparticles found in industry ranging from food additives to energy generation. Approximately four million tons of TiO(2) particles are produced worldwide each year with approximately 3000 tons being produced in nanoparticulate form, hence exposure to these particles is almost certain. RESULTS: Even though TiO(2) is also used as an anti-bacterial agent in combination with UV, we have found that, in the absence of UV, exposure of HeLa cells to TiO(2) nanoparticles significantly increased their risk of bacterial invasion. HeLa cells cultured with 0.1 mg/ml rutile and anatase TiO(2) nanoparticles for 24 h prior to exposure to bacteria had 350 and 250 % respectively more bacteria per cell. The increase was attributed to bacterial polysaccharides absorption on TiO(2) NPs, increased extracellular LDH, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO(2) particles ingested 40 % fewer bacteria, further increasing the risk of infection. CONCLUSIONS: In combination, these two factors raise serious concerns regarding the impact of exposure to TiO(2) nanoparticles on the ability of organisms to resist bacterial infection. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12951-016-0184-y) contains supplementary material, which is available to authorized users.