(633c) Antibody-Conjugated Gold Nanoclusters (Nanoroses) for Targeted Cancer Cellular Imaging and Therapy

The ability of 30 to 100 nm nanoparticles to target and modulate the biology of specific cell types can enable major advancements in cellular imaging and therapy in cancer and atherosclerosis. A key challenge is to combine targeting, imaging, and therapeutic functionality into small, yet stable nanoparticles. We report ~30 nm stable uniformly-sized near infrared (NIR) active, superparamagnetic nanoclusters formed by kinetically controlled self-assembly of gold-coated iron oxide nanoparticles. The controlled assembly of nanocomposite particles into clusters with short primary particle spacing produces collective optical response of the electrons that shift absorbance into the NIR. The epidermal growth factor receptor (EGFR) is a protein tyrosine kinase over expressed on many types of tumor cells, including breast, ovarian, bladder, and prostatic carcinoma. Anti-EGFR conjugated gold nanoroses show efficient binding to the EGFR in cancer cell lines, which facilitates NIR imaging contrast enhancement and therapy. Because of the thin gold shells on the particles, the r2 spin-spin magnetic relaxivity is 200 mM-1s-1, an order of magnitude larger than observed for typical iron oxide particles. The high relaxivity is utilized for magnetic resonance imaging (MRI) in a mouse model. The increased capacity of anti-EGFR conjugated gold nanoroses has the potential to activate signal transduction pathways that regulate cell proliferation, and therefore to inhibit in vivo tumor growth. Antibody conjugated nanoclusters with optical, magnetic and therapeutic functionality, designed by assembly of nanoparticle building blocks, can provide broad opportunities for targeted cancer cellular imaging, therapy, and combined imaging and therapy.