Impact of agglomeration on the bioaccumulation of sub-100 nm sized TiO₂.

To improve our understanding on the impact of extrinsic properties of NPs on their bioaccumulation and toxicity, we have investigated the bioaccumulation of sub 100 nm sized P25 TiO₂ nanoparticles (NPs) by Daphnia magna (D. magna) in toxicity testing media. Based on our quantitative ICP-MS measurements as well as spectromicroscopic observations, we found that the bioaccumulation by D. magna were strongly influenced by the extrinsic properties of NPs as well as the biological uptake characteristics of D. magna. New sets of effective dosimetry parameters well correlated with the amount of NPs bioaccumulated within D. magna were also proposed. Based on these findings, we suggested that the extrinsic physicochemical properties of NPs (e.g., interfacial and colloidal properties of NPs) and biological characteristics for NPs (e.g., uptake cutoff sizes of testing organisms) should be considered and included when developing alternative dosimetry of NPs.