Influence of dispersive agent on nanomaterial agglomeration and implications for biological effects in vivo or in vitro

Comparing the dispersing properties of the porcine lung surfactant Curosurf® to bovine serum albumin (BSA), the present study investigated how a more close simulation of the in vivo situation influences nanomaterial dispersion and hence the proportion of the administered dose that will reach the in vitro test system, i.e. the 'effective dose'. Dispersions of 16 OECD reference nanomaterials (ZnO, Ag, TiO2, CeO2, SiO2, and multi-walled carbon nanotubes (MWCNTs) were assessed. Overall, the NMs were better dispersed in the BSA-supplemented medium. BSA-addition combined with ultrasonication proved most effective in deagglomerating MWCNTs, but also reduced agglomeration for most metal oxide nanomaterials as compared to the Curosurf® dispersions. However, all materials were at least partially agglomerated in either dispersing agent. For the different nanomaterials, the calculated effective dosage upon 12- or 24-h test substance incubation differed considerably (and to different extents) depending on the applied dispersing agent. When testing nanomaterial effects in vitro, selection of the type of cell culture medium and its additives should take into account what the system is intended to mimic. Study protocols should address whether they aim at best-possible dispersion of the nanomaterials or at simulating more realistically in vivo tissue uptake and distribution.