ABSTRACT. The nuclear membrane is one of the major cellular barriers in the delivery of plasmid DNA (pDNA). Cell division has a positive influence on the expression efficiency since at the end of mitosis, pDNA or pDNA containing complexes near the chromatin are probably included by a random process in the nuclei of the daughter cells. However, very little is known about the nuclear inclusion of nanoparticles during cell division. Using the Xenopus nuclear envelope reassembly (XNER) assay, we found that the nuclear enclosure of nanoparticles was dependent on size (with 100 nm and 200 nm particles being better included than the 500 nm ones) and charge (with positively charged particles being better included than negatively charged or poly-ethyleneglycolated (PEG-ylated) ones) of the 2 beads. Also, coupling chromatin-targeting peptides to the polystyrene beads or pDNA complexes improved their inclusion by 2-to 3-fold. Upon microinjection in living HeLa cells, however, nanoparticles were never observed in the nuclei of cells post-division but accumulated in a specific perinuclear region, which was identified as the lysosomal compartment. This indicates that nanoparticles can end up in the lysosomes even when they were not delivered through endocytosis. To elucidate if the chromatin binding peptides also have potential in living cells, this additional barrier first has to be tackled, since it prevents free particles to be present near the chromatin at the moment of cell division.