(198b) Polymer Coated Gold-Ferric Oxide Superparamagnetic Nanoparticles for Theranostic Applications

A multifunctional magnetic nanoparticle (NP) is designed to perform a near-infrared (NIR)-responsive remote control photothermal ablation for the treatment of breast cancer. In contrast to the previously reported studies of gold (Au) magnetic (Fe3O4) core-shell nanoparticles (NPs), a Janus-like nanostructure is synthesized with Fe3O4 NPs decorated with Au resulting in an approximate size of 60 nm mean diameter. Epigallocatechin-3-gallate (EGCG), a ubiquitous bioactive polyphenol available in green tea, was adsorbed on the surface of Au–Fe3O4 NPs as a cell membrane targeting and cell growth inhibition ligand. Poly- l-lysine (PLL) was used for the surface functionalization of trisoctahedral Au–Fe3O4 NPs to deliver the NPs inside cells and function as a hydrophilic block for steric stabilization of the NPs in biological media. The PLL coating increased the colloidal stability and robustness of Au–Fe3O4 NPs (PLL–Au–Fe3O4). The unique properties of both Au surface plasmon resonance and superparamagnetic moment result in a multimodal platform for use as a nanothermal ablator and also as a magnetic resonance imaging (MRI) contrast agent, respectively. Taking advantage of the photothermal therapy, PLL–Au–Fe3O4 NPs were incubated with BT-474 and MDA-MB-231 breast cancer cells, investigated for the cytotoxicity and intracellular uptake, and remotely triggered by a NIR laser of ~808 nm (1 W/cm2 for 10 min). It is revealed that no significant (<10%) cytotoxicity was induced by PLL–Au–Fe3O4 NPs itself in BT-474 and MDA-MB-231 cells at concentrations up to 100 mg/ml. As soon as the NPs were triggered by a photothermal NIR laser, approximately 40 and 60% of BT-474 and MDA-MB-231 breast cancer cell death, respectively were observed using 100 mg/ml PLL–Au–Fe3O4 NPs, while the cells with the NPs but without laser showed <10% cell death compared to no laser treatment control. Combined together, the results demonstrate a new polymer gold superparamagnetic nanostructure that integrates both diagnostics function andphotothermal ablation of tumors into a single multimodal nanoplatform exhibiting a significant cancer cell death.