Laser-induced
phototherapy is a new
therapeutic use of electromagnetic radiation for
cancer treatment. The use of targeted plasmonic
gold nanoparticles can reduce the
laser energy necessary for selective
tumor cell destruction. However, the ability for targeted delivery of the currently used
gold nanoparticles to
tumor cells is limited. Here, we describe a new class of molecular specific photothermal coupling agents based on hollow
gold nanoshells (HAuNS; average diameter, approximately 30 nm) covalently attached to
monoclonal antibody directed at
epidermal growth factor receptor (EGFR). The resulting anti-EGFR-HAuNS exhibited excellent colloidal stability and efficient photothermal effect in the near-infrared region. EGFR-mediated selective uptake of anti-EGFR-HAuNS in EGFR-positive A431
tumor cells but not
IgG-HAuNS control was shown in vitro by imaging scattered light from the nanoshells. Irradiation of A431 cells treated with anti-EGFR-HAuNS with near-infrared
laser resulted in selective destruction of these cells. In contrast, cells treated with anti-EGFR-HAuNS alone,
laser alone, or
IgG-HAuNS plus
laser did not show observable effect on cell viability. Using 111In-labeled HAuNS, we showed that anti-EGFR-HAuNS could be delivered to EGFR-positive
tumors at 6.8% ID/g, and the microscopic image of excised
tumor with scattering signal from nanoshells confirmed preferential delivery to A431
tumor of anti-EGFR-HAuNS compared with
IgG-HAuNS. The absence of
silica core, the relatively small particle size and high
tumor uptake, and the absence of cytotoxic
surfactant required to stabilize other
gold nanoparticles suggest that immuno-HAuNS have the potential to extend to in vivo molecular
therapy.