The biological response of organisms exposed to nanoparticles is often studied in vitro using adherent monolayers of cultured cells. In order to derive accurate concentration-response relationships, it is important to determine the local concentration of nanoparticles to which the cells are actually exposed rather than the nominal concentration of nanoparticles in the cell-culture medium. In this study, the sedimentation–diffusion process of different sized and charged gold nanoparticles has been investigated in vitro by evaluating their settling dynamics and by developing a theoretical model to predict the concentration depth-profile of nanoparticles in solution over time. Experiments were carried out in water and in cell-culture media at a range of controlled temperatures. The optical phenomenon of caustics was exploited to track nanoparticles in real-time in a conventional optical microscope without any requirement for fluorescent labelling that potentially affects the dynamics of the nanoparticles. The results obtained demonstrate that size, temperature and the stability of the nanoparticles play a pivotal role in regulating settling dynamics of nanoparticles. For gold nanoparticles larger than 60 nm in diameter, the initial nominal concentration did not accurately represent the concentration of nanoparticles local to the cells.

The dataset consist of TIF files related to the raw z-stacks aquired of the gold nanoparticles suspension tested. Each TIF file contains images acquired progressively from the bottom (1st image at 0 μm) to the top (last image at 250 μm ± 10 μm) of each nanoparticles suspension at a given acquisition time. For more info related to the technique used to acquire the images please refer to the original manuscript.

The file name of each TIF file contains all the information related to the nanoparticles and solution properties and of the time step of acquisition:

File_name= size_charge_solution_temperature_acquisition time