Hydrogel pullulan nanoparticles encapsulating pBUDLacZ plasmid as an efficient gene delivery carrier

This study provides a method for enhancing the delivery of nucleic acid molecules to cells by encapsulating it inside the hydrogel pullulan nanoparticles. In this study, pullulan nanoparticles encapsulating pBUDLacZ plasmid have been prepared inside the aqueous droplets of w/o microemulsions. Transmission electron microscopy (TEM) image showed that the particles are spherical in shape with size of 45+/-0.80 nm diameter. Cell cytotoxicity studies as determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay demonstrated that cells incubated with nanoparticles remained more than 100% viable at nanoparticle concentration as high as 1000 mug/ml. From scanning electron microscope images, it was observed that the nanoparticles were internalised and the cells exhibited vacuoles in the cell body due to nanoparticle internalisation. Endocytosis of nanoparticles resulted in disruption of F-actin and beta-tubulin cytoskeleton of human fibroblasts. The efficacy of transfection in vitro on HEK293 and COS-7 cells demonstrated cell type dependence, with COS cells having a higher gene expression. The beta-gal expression in COS-7 cells by pullulan nanoparticle was comparable to commercially available Lipofectamine 2000. The results of this study are encouraging for the development of pullulan nanoparticles as an intracellular delivery system for drugs and genes. (C) 2004 Elsevier B.V. All rights reserved.