Intracellular uptake and release of poly(ethyleneimine)-co-poly(methyl methacrylate) nanoparticle/pDNA complexes for gene delivery

Our previous studies demonstrated that cationic nanoparticles composed of well-defined poly(methyl methacrylate) (PMMA) cores surrounded by a hairly poly(ethyleneimine) (PEI) shells have comparative advantages over the PEI system for gene delivery. In this study, we focused on the intracellular uptake and release of PEI–PMMA nanoparticle/pDNA complexes. The behavior of the nanoparticle/pDNA complexes in recipient cells was monitored by using confocal laser scanning microscopy. We found that the nanoparticle/pDNA complexes were internalized very effectively by endocytosis. In the recipient cells the nanoparticles were found localized in the cytoplasm. At the same time, the pDNA carried by the nanoparticles successfully detached from the nanoparticles and localized in the nucleus of the HeLa cells.