Targeted photothermal tumor therapy using metal nanoshells

Complications associated with invasive malignant tumor excision have led to alternative treatment methods including chemotherapy, photodynamic therapy, and thermal coagulation. Metal nanoshells, which are a new class of optically active nanoparticles, may provide a novel means of targeted photothermal therapy in tumor tissue, minimizing damage to surrounding healthy tissue. Metal nanoshells possess a strong tunable absorption, which can be placed in the near IR where maximal penetration of light through tissue is achieved. When conjugated with a tumor-specific protein, these nanoshells could be systematically injected, but preferentially bound to the tumor site. Near IR light administered at the site would heat the localized nanoshells, killing the tumor. We have successfully conjugated antibodies against oncoproteins to nanoshells and demonstrated specific binding to tumor cells. Furthermore, we have demonstrated photothermally-induced death of nanoshell-bound carcinoma cells in vitro, as well as in vivo. These studies utilized an 821 nm diode laser, and nanoshells fabricated with their plasmon resonance at 821 nm. Cell death was limited to the laser spot, and under control conditions (no nanoshells or no light), no cell death or tissue damage was observed.