(190i) Polymer-Coated-Gold Nanorods for Administration of Extracellular Hyperthermia and Delivery of Nucleic Acids to Cancer Cells

Gold nanoparticles have been investigated as potential therapeutics, drug delivery vehicles, imaging agents and diagnostics due to their unique properties, including enhanced surface plasmon resonance, high biocompatibility, and ease of chemical conjugation. We demonstrate that the poor stability of CTAB-templated gold nanorods in biologically relevant media can be enhanced by layer-by-layer deposition of polyelectrolytes. Gold nanorods coated with cationic polymers synthesized in our laboratory were stable up to four weeks and were less cytotoxic to mammalian cells than those coated with 25-kDa polyethyleneimine (pEI25). We successfully employed polyelectrolyte-coated nanorods for the photothermal ablation of PC3-PSMA cells using NIR laser irradiation and for delivering plasmid DNA to these cells at sub-toxic concentrations. We also evaluated the spatiotemporal temperature distribution and cell death induced by gold nanorod induced extracellular hyperthermia in which the nanoparticles were maintained in the dispersion outside human prostate cancer cells. Experimentally determined spatiotemporal distribution of temperature generated by nanorod dispersion following near infrared (NIR) irradiation was correlated to the viability of human prostate cancer cells. This information was subsequently employed to develop and validate theoretical models of temperature distribution and cell death following laser-induced irradiation of gold nanorods maintained in the extracellular dispersion. Taken together, our results demonstrate the polymers / polyelectrolyte can be employed for improving the stability of gold nanorods which, in turn, facilitates photothermal ablation of cancer cells and delivery of nucleic acids using these nanoassemblies.