169. Polymer Functionalized Gold Nanoparticles in Gene Delivery In Vitro

Abstract

Non-viral gene delivery approaches have been extensively studied as a basic tool for intracellular gene transfer and gene therapy especially for genetic aberrations including cancer. Gold nanoparticles have attracted strong biomedical interest for drug/gene delivery due to their low toxic nature, surface plasmon resonance and capability of increasing the stability of the payload. In the present study the synthesis of photoluminescent nanoparticles consisting of a gold core coated with polyethyleneimine, poly-L-lysine, cysteine and chitosan is reported. These functionalized gold nanoparticles (FAuNPs) were investigated at different pH values and ionic strength to identify the optimum conditions to produce stable monodisperse nanoparticles. FAuNPs showed good stability at low ionic strength which is important for the flexibility of the polymer chain. All nanoparticle/polymer formulations showed spherical particles in the size range 11.9-195 nm with narrow particle distributions and low PDI (<1.2). Nanoparticle and pDNA complexation was efficiently demonstrated in the band shift and ethidium bromide intercalation assays respectively, with serum nuclease digestion revealing partial protection of theResults: Our novel PEGylated PLGA nanoparticles (without siRNA) showed higher accumulation and extended residence time in the inflamed foot of lipopolysaccharide (LPS)-induced mouse model of chronic inflammation. TNF-α-siRNA-NPs were 176.6±15.8 nm in diameter, with a zeta potential of -25.2±2.0 mV and an entrapment efficiency of 31±4%. The nanoparticles were stable in simulated biological medium. In vitro, less than 40% of the siRNA was released with 72 h at 37oC. Finally, TNF-α-siRNA-NPs significantly decreased TNF-α release from J774A.1 cells.complexed plasmid DNA (pCMV-luc). MTT cytotoxicity experiments indicated that the FAuNPs elicited a dose dependent cytotoxic effect in four mammalian cell lines (HepG2, HEK293, HeLa and Caco2). Au-PEI/pDNA maintained over 80% cell viability across all cell lines, while the Au-cys/pDNA exhibited a significant 91.8% (p<0.001) in Caco2 cells, Au-Chit/pDNA 126% (p<0.01) in HepG2 cells and Au-PLL/pDNA 104% in Hela cells. Transfection studies were accomplished using the luciferase reporter gene assay. Results showed that the FAuNPs produced greater transgene activity than the cationic polymer/DNA complexes on their own. This was evident for the Au-PEI/pDNA complex which produced a 12 fold increase in the HEK293 cells and a 9 fold increase in the HepG2 cells, compared to the PEI/pDNA complexes. The results of this study suggest that FAuNP's low cytotoxicity coupled with the ability to parametrically control particle size and surface properties, make these nanoparticles suitable non-viral gene delivery vectors. However further engineering and modifications of the FAuNPs may be required to enable in vivo gene delivery.