Uptake and Intracellular Fate of Fluorophore Labeled Metal–Organic-Framework (MOF) Nanoparticles

[Image: see text] The uptake and the fate of Zr-based metal–organic-framework nanoparticles labeled with organic fluorophores in HeLa cells has been monitored with fluorescence detection and elemental analysis. The nanoparticles have been selected as a model system of carrier nanoparticles (here Zr-based metal–organic-framework nanoparticles) with integrated cargo molecules (here organic fluorophores), with aze that does not allow for efficient exocytosis, a material which only partly degrades under acidic conditions as present in endosomes/lysosomes, and with limited colloidal stability. Data show that, for Zr-based metal–organic-framework nanoparticles of 40 nm size as investigated here, the number of nanoparticles per cells decreases faster due to particle redistribution upon proliferation than due to nanoparticle exocytosis and that, thus, also for this system, exocytosis is not an efficient pathway for clearance of the nanoparticles from the cells.