Evaluation of photothermal therapy of breast cancer with shape-controlled gold nanoparticles with 18F-FDG-PET/CT

644 Objectives Three distinct shapes of gold nanoparticles (nanorods, nanocages, and nanohexapods) were prepared and evaluated as photothermal therapeutic agents against breast cancer in a mouse tumor model. The treatment response was characterized with 18F-fluorinated deoxyglucose positron emission tomography/computed tomography (18FDG-PET/CT) imaging. Methods Suspensions of pegylated gold nanorods, nanocages, and nanohexapods in buffers were irradiated with an 808 nm diode laser to quantify photothermal conversion efficiency. Nanoparticles were incubated with MDA-MB-435 breast cancer cells to evaluate the cytotoxicity and cell uptake. In vivo biodistribution studies were performed at 1 and 7 days post injection via the tail vein of MDA-MB-435-tumor-bearing nude mice. Photothermal studies were performed by irradiating tumors for 10 minutes while acquiring thermal images with a NIR camera. 18F-FDG-PET/CT imaging was performed pre- and post-treatment to assess the treatment response. Results Substantial photothermal heating was observed with all three shapes of nanoparticles. In vitro cytotoxicity and cell uptake assays showed that the nanohexapod was the least toxic and had the highest uptake compared to the other shapes. Biodistribution studies demonstrated that nanorods and nanohexapods accumulated in tumors significantly more than nanocages. The in vivo photothermal treatment studies showed significant increase of tumor temperature and reduction of 18F-FDG tumor uptake for all shapes after irradiation, with the nanohexapods providing the largest temperature increase. Conclusions All three shapes of gold nanostructures demonstrated their potential as photothermal transducers for cancer treatment. Among them, gold nanohexapods offer potentially superior properties compared to other shapes due to their high photothermal conversion efficiency, low cytotoxicity, and high cell uptake and tumor accumulation. Research Support This work was supported by a grant from the NCI (R01 CA138527).