Hydroxyethyl-functionalized ultrasmall chitosan nanoparticles as a gene delivery carrier

Abstract

A non-viral gene vector based on hydroxyethyl ultra-low molecular weight chitosan nanoparticles (HE-ULMWCh NPs) has been synthesized. The HE-ULMWCh is used to form nanoparticles with an enhanced green fluorescence protein (pEGFP) encoding plasmid that possesses diameters of 30–50 nm and a molecular weight of less than 2 kDa. The cytotoxicity assay shows that this new gene vector is significantly less cytotoxic than polyethylenimine whilst still retaining the characteristics of a cationic polyelectrolyte. Cellular uptake of HE-ULMWCh NP–pDNA nanocomplexes shows that HE-ULMWCh NPs can readily enter into cells via endocytosis and then be delivered to lysosomes. pDNA can be easily released from HE-ULMWCh NPs in the acidic vesicles of lysosomes, therefore resulting in a significant increase in the transfection efficiency in three different cell lines compared to naked pDNA. The in vitro results using the new gene vector are further confirmed by in vivo transfection in which HE-ULMWCh NPs provided 3.2 fold greater transfection efficiency than naked pDNA. The HE-ULMWCh NPs can therefore be concluded to be a promising delivery system for in vitro and in vivo gene transfection.