Cellular Uptake of Mildly Oxidized Nano-Graphene for Drug-Delivery Applications

Graphene family materials (GFM) have large perspectives for drug delivery
applications but their internalization in live cells is under investigation in a wide variety of studies in
order to assess the best conditions for efficient cellular uptake. Here we show that mild oxidation of
graphene nanoplatelets produces nano-graphene oxide (nGO) particles which are massively
internalized into the cell cytoplasm. This remarkable uptake of nGO in NIH-3T3 cells has never been
observed before. We performed vitality tests for demonstrating the biocompatibility of the material
and analyzed the internalization mechanism under different oxidation degrees and concentrations.
Moreover, we evaluated quantitatively, for the first time, the cell volume variation after nGO
internalization in live cells through a label-free digital holographic imaging technique and in quasi
real-time modality, thus avoiding the time consuming and detrimental procedures usually employed
by electron-based microscopy. The results demonstrate that nGO formulations with a tailored balance
between exposed surface and content of functional groups are very promising in drug delivery
applications.