Role of nanoparticle-Cell interface on membrane crossing and cytotoxicity

Understanding the interactions of nanoparticles (NP) with the cell membrane and their trafficking through the cells is very relevant to fully explore the use of NP for efficient delivery of therapeutics and to reduce their cytotoxicity. Despite numerous efforts to establish a structure†"function relationship between NP physico-chemical properties and their interactions with biological systems, the possibility to predict the fate of NP remains still far. In this thesis we assume that the way by which NP cross the cell membrane dictates their fate. To test this hypothesis, first, we studied the effect of NP delivery across cell membrane in controlling metal-containing NP (MNP) toxicity. In particular, we delivered MNP across the cell membrane directly inside the cytosol by using a pneumatic method -a gene gun - thus bypassing the formation of endocytic vesicles. We found that the cytotoxicity of MNP is strictly reliant upon the pathway of cellular membrane crossing and their localization. In particular, if otherwise toxic MNP are allow to enter the cell bypassing any form of active-dependent mechanism as endocytosis, no significant cytotoxic effect is showed. Starting from these results, we designed surface decorated NP by using a bio-inspired approach in order to control NP entrance and to escape the lysosomal pathway. The results show that the decoration of polystyrene NP with Herpes simplex virus type one derived gH-625 peptide affected NP intracellular distribution by reducing NP accumulation within the lysosomes, increasing intracellular free “random walk” behavior, reducing NP toxicity and enhancing blood-brain barrier crossing.