Protamine and Chloroquine Enhance Gene Delivery and Expression Mediated by RNA-Wrapped Single Walled Carbon Nanotubes

The use of non-viral vectors as delivery systems in gene therapy has been extensively studiedrecently owing to their advantages over viral vectors. Here, we propose a new gene delivery systembased on the use of RNA-wrapped single-walled carbon nanotubes (SWCNTs) complexed with thecationic protein, protamine and the drug chloroquine. Protamine was selected as a cationic proteinacting as bridge between negatively charged RNA-wrapped SWCNTs and plasmid DNA. Protaminealso contains a nuclear localization signal which enhances the expression of the transfected gene.The drug chloroquine, a lysosomotropic compound which has been reported to increase the transfectionefficiency, was attached to RNA-wrapped SWNTs by ionic interactions. The simultaneousdelivery of the drug chloroquine with plasmid DNA clearly showed an enhanced gene delivery andexpression. The levels of gene expression were quantified using the luciferase reporter gene asmodel. Optimal conditions for transfection and gene expression were obtained and cytoxicity of thecarbon nanotube complexes measured. The optimal complexes were shown to efficiently deliverplasmid DNA for efficient gene expression and may thereby be useful as gene delivery systems forgene therapy.