Impact of silica nanoparticle concentration and cell doubling time on intracellular distribution via nanotomography

Silica nanoparticles (SiNPs) are recognized as promising platforms for diagnosing and treating diseases¹. Advancing nanomedicine requires a thorough understanding of how these nanoparticles interact with cells. Several factors critically influence the cellular uptake of SiNPs, with one key aspect being the protein corona, which substantially alters nanoparticle-cell interactions². Here, we consider the effects of protein corona on SiNPs, considering previous research that has presented a meaningful cytotoxicity reduction³. We show that the spatial distribution of SiNPs within cells is influenced by both nanoparticle concentration and cell doubling time. This was investigated using 3D imaging acquired through cryo-soft X-ray tomography (cryo-SXT) and super-resolution fluorescence structured illumination microscopy (cryo-SIM) at the B24 beamline of Diamond Light Source. The data indicate that SiNPs are internalized via vesicles across all concentrations, localizing in the cytosol. Notably, at higher concentrations, SiNPs were also found within the cell nucleus, a phenomenon not observed at lower concentrations. Moreover, the nanoparticles predominantly aggregated in the perinuclear region after two cell doubling times. These findings have significant implications for nanomedicine, offering three-dimensional characterization and high-resolution ultrastructural imaging of cells with nanoparticles using an innovative technique.