Due to the safety concerns surrounding viral vectors, non-viral alternatives are desirable for fulfilling the aim of gene therapy. In this project gel mobility shift assays demonstrated how cross-linked PVA nanoparticles successfully form complexes with plasmid DNA and are of a size and charge that should, theoretically, permit endocytosis by eukaryotic cells. However, during in vitro transfection studies no reporter (GFP) gene expression was noted. The collective evidence from electroporation, fluorescent-DNA-tagging, Lipofectin® or calcium phosphate chimeric and chloroquine experiments suggest that a lack of cell uptake is responsible. Nevertheless, the same cross-linked PVA nanoparticles have been shown to exhibit much promise in the field of drug delivery during in vitro experiments, even when used to target the same cell types as those used during transfection studies. Nanagel®, a cross-linked PVA nanoparticle containing budesonide, achieved higher levels of drug delivery than a commercially available form of the same drug (Pulmicort®) after 1 or 24 hours drug exposure. Furthermore, by measuring superoxide production during a stimulated respiratory burst, the budesonide delivered to cells appears fully functional and significantly more effective than Pulmicort® in preventing the formation of reactive oxygen species, following a 24-hour pre-treatment period with the formulation. These findings have exciting possibilities for the use of hard-to-dissolve corticosteroids in the treatment of respiratory disease. / AGT Sciences Ltd