Biodegradation of Bi-Labeled Polymer-Coated Rare-Earth Nanoparticles in Adherent Cell Cultures

The fate of polymer-coated Eu- and Bi-doped GdVO4 nanoparticles (NPs) of cubic shape upon cellular internalization was investigated. After having been endocytosed by cells, the cubic Eu- and Bi-doped GdVO4 NP cores were partly dissolved and reshaped to rounded structures, which in control experiments could be ascribed to the acidic conditions present in endosomes/lysosomes. With progress of time, there was a significant reduction in the amount of internalized NPs per cell due to proliferation. This was of higher extent than NP exocytosis. Data of the study are compatible with the scenario that endosomal/lysosomal enzymes may partly digest the polymer shell around the NP cores, with enhanced exocytosis of the polymer fragments as compared to the NP cores.