(321f) Photothermal Ablation and Non-Viral Gene Delivery of Cancer Cells Using Polyelectrolyte-Stabilized Gold Nanorods

Gold nanoparticles possess a number of attractive properties including enhanced surface electric field, high biocompatibility, and ease of chemical conjugation. Consequently, gold nanoparticles are being increasingly investigated as potential therapeutics, drug delivery vehicles, imaging agents and diagnostics as part of the expanding field of nanomedicine. In particular, gold nanorods demonstrate a tunable photothermal response to near infrared (NIR) light have been employed for the ablation of cancer cells, biomolecule detection and the generation of functional nanoscale assemblies. We demonstrate that cetyltrimethyl ammonium bromide (CTAB)-based gold nanorods, prepared by the commonly used seed-mediated method, demonstrate poor stability in phosphate buffered saline (PBS), serum-free media (SFM) and serum-containing media (SCM), depending on the number of centrifugation steps carried out to remove excess CTAB from the dispersion. We employed the layer-by-layer deposition of recently generated cationic polymers in our laboratory in order to increase the short-term and long-term stability of gold nanorods in biological media, Polyelectrolyte-coated gold nanorods exhibit excellent long term optical stability in all three biologically media even after four weeks of storage. In addition, stabilization of the optical response resulted in a reliable, Arrhenius-like photothermal response of the well-dispersed gold nanorods over the period of investigation. Cytotoxicity evaluation indicated that gold nanorods coated with our polymers were less cytotoxic to mammalian cells than those covered with 25-kDa polyethyleneimine (pEI25). Stable and biocompatible polyelectrolyte-coated nanorods were successfully employed for the photothermal ablation of PC3-PSMA cells using NIR laser irradiation. In addition, sub-toxic concentrations of these nanorods were also employed for delivering plasmid DNA to these cells. Our results indicate that molecular engineering of cationic polyelectrolytes can lead to stable, biocompatible gold nanorod assemblies that can be useful for a variety of applications including non-viral gene delivery and cancer cell photothermal ablation.