Bi, a high atom number element, has a high photoelectric absorption coefficient, and Se element has anticancer activity. Hence, their compound chalcogenide (Bi2Se3) deserves a thorough investigation for biomedical applications. This study reveals that Bi2Se3 nanoplates (54 nm wide) protected with poly(vinylpyrollidone) (PVP) are biocompatible and have low toxicity even at a high dose of 20 mg/kg in mice. This conclusion was made through the studies on the biodistribution and 90-day long term in vivo clearance of the nanoplates. Liver and spleen were dominant organs for the nanoplates accumulation which was mainly due to RES absorption, but 93 % the nanoplates were cleared after 90 days treatment. Concentrations of Bi and Se in tumor tissue continuously increased until 72 h after intraperitoneal injection into mice. Such selective accumulation of Bi was utilized to enhance the contrast of X-ray CT images. The Bi elements concentrated in a tumor led to damage on the tumor cells when exposed to gamma radiation. Growth of the tumor significantly delayed and stopped after 16 days after the tumor was treated with the Bi2Se3 nanoplates and radiation. This work clearly shows that the Bi2Se3 nanoplates may be used for cancer radiation therapy and CT imaging. They deserve further studies for biological and medical applications.

Metabolizable Bi2Se3 Nanoplates: Biodistribution, Toxicity, and Uses for Cancer Radiation Therapy and Imaging