Contrast ultrasound-guided photothermal therapy using gold nanoshelled microcapsules in breast cancer

The purpose of this study was to test whether dual functional gold nano-shelled microcapsules (GNS-MCs) can be used as an ultrasound imaging enhancer and as an optical absorber for photothermal therapy (PTT) in a rodent model of breast cancer.

GNS-MCs were fabricated with an inner air and outer gold nanoshell spherical structure. Photothermal cytotoxicity of GNS-MCs was tested with BT474 cancer cells in vitro and non-obese diabetes-SCID (NOD/SCID) mice with breast cancer. GNS-MCs were injected into the tumor under ultrasound guidance and treated with near-infrared (NIR) laser irradiation. The photothermal ablative effectiveness of GNS-MCs was evaluated by measuring the surface and internal temperature of the tumor as well as the size of the tumor using histological confirmation.

NIR laser irradiation resulted in significant tumor cell death in GNS-MCs-treated BT474 cells in vitro. GNS-MCs were able to serve as an ultrasound enhancer to guide the intratumoral injection of GNS-MCs and ensure their uniform distribution. In vivo studies revealed that NIR laser irradiation increased the intratumoral temperature to nearly 70°C for 8 min in GNS-MCs-treated mice. Tumor volumes decreased gradually and tumors were completely ablated in 6 out of 7 mice treated with GNS-MCs and laser irradiation by 17 days after treatment.

This study demonstrates that ultrasound-guided PTT with theranostic GNS-MCs is a promising technique for in situ treatment of breast cancer.