(679g) Poly(amino ether)-Gold Nanorod Assemblies for shRNA Delivery

James Ramos, Kaushal Rege

As the field of nanotechnology continues to grow, many novel nanomaterials are showing strong potential for use in the biomedical field. Gold nanorods (GNRs) have emerged as one such nanomaterial with the capacity for use in biosensing, imaging, photothermal therapy and gene delivery as a cancer therapy. Using polymers from a novel poly(amino ether) library synthesized in our laboratory, we have synthesized poly(amino ether) coated GNRs (PAE-GNRs) by depositing polyelectrolyte multilayers on cetyltrimethyl ammonium bromide (CTAB)-based gold nanorods. These PAE-GNRs exhibit an increase in the nanoparticles stability as well as the capacity to electrostatically bind to nucleic acids. We have previously shown the PAE-GNRs ability to deliver plasmid DNA to two different prostate cancer cell lines for enhanced transgene delivery when compared to GNRs deposited with polyethylenimine, a current standard for polymer mediated gene delivery. Here we show the capability for the PAE-GNRs to delivery shRNA for gene knockdown. By loading the PAE-GNRs with shRNA targeted against the luciferase reporter gene and using them to treat cancer cell lines that constitutively express the luciferase, we demonstrate the ability of the PAE-GNRs to deliver the shRNA for gene silencing. This is confirmed by the observed reduction in luciferase expression levels compared to no treatment and delivery of non-silencing nucleic acids. By optimizing the shRNA loading amount, treatment times, and PAE-GNR concentrations we have determined the ideal treatment conditions for maximum gene silencing. These conditions can then be translated for delivery of shRNA targeted against a therapeutically relevant target as a gene therapy to combat disease. Additionally, due to the unique optical properties of the GNRs, we also demonstrate the ability to image the nanoassemblies after delivery in vitro using two-photon induced luminescence of the GNRs. This can be translated as a labeling/detection application for PAE-GNR assemblies modified with moieties targeted to a specific cell type. Our results indicate that the engineering of the PE-GNRs leads to a gold nanoassembly that combines high stability with low cytotoxicity and the capacity to mediate shRNA delivery for gene silencing, as well as be used for TPL imaging. These PE-GNRs also have the potential to be used for photothermal ablation, photothermal enhanced delivery, and carrying of other small anionic molecules for delivery making them a powerfully potential single platform theranostic nanomaterial.