A Three-Dimensional Cell Culture Platform for Long Time-Scale Observations of Bio-Nano Interactions.

We know surprisingly little about the long-term outcomes for nanomaterials interacting with organisms. To date, most of what we know is derived from in vivo studies that limit the range of materials studied and the scope of advanced molecular biology tools applied. Long-term in vitro nanoparticle studies are hampered by a lack of suitable models, as standard cell culture techniques present several drawbacks, while technical limitations render current three-dimensional (3D) cellular spheroid models less suited. Now, by controlling the kinetic processes of cell assembly and division in a non-Newtonian culture medium, we engineer reproducible cell clusters of controlled size and phenotype, leading to a convenient and flexible long-term 3D culture that allows nanoparticle studies over many weeks in an in vitro setting. We present applications of this model for the assessment of intracellular polymeric and silica nanoparticle persistence and found that hydrocarbon-based polymeric nanoparticles undergo no apparent degradation over long time periods with no obvious biological impact, while amorphous silica nanoparticles degrade at different rates over several weeks, depending on their synthesis method.