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Graphene family materials (GFMs) 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 nanographene 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 the exposed surface and content of functional groups are very promising in drug-delivery applications.

The demand for sensors capable of measuring low-abundant collagen in human fluids has highly increased in recent years. Indeed, collagen is expected to be a biomarker for chronic diseases and could monitor their progression. Here we show detection of highly diluted samples of collagen at picogram level thanks to an innovative pyro-electrohydrodynamic jet (p-jet) system. Through the intense electric fields generated by the pyroelectric eect in a ferroelectric crystal, the collagen solution was concentrated on a small area of a slide that was appropriately functionalized to bind proteins. The collagen molecules were labeled by an appropriate fluorophore to show how the number of tiny droplets influences the limit of detection of the technique. The results show that the p-jet is extremely promising for overcoming the current detection limits of collagen-based products in human fluids, performing 10 times better than the enzyme-linked immunosorbent assay (ELISA) and thus paving the way for the early diagnosis of related chronic diseases.