High‐Security Multifunctional Nano‐Bismuth‐Sphere‐Cluster Prepared from Oral Gastric Drug for CT/PA Dual‐Mode Imaging and Chemo‐Photothermal Combined Therapy In Vivo

Abstract Multifunctional nanoprobes that can be applied for real‐time monitoring or precision treatment of tumors have received wide interest among researchers. However, most of these nanoprobes are obtained through chemical synthesis, and thereby may contain toxic residues or harmful reagents. In this article, a nano‐bismuth‐sphere‐cluster (Bi) is synthesized via a one‐step method (after an irradiation with ultra‐violet) and is then applied in dual‐mode computed tomography/photoacoustic imaging. Bismuth potassium citrate granules, which is a common gastric drug that is highly safe and has a low price (<1 China Yuan/g), is used as the only raw material. The results show that the Bi cluster has good stability with sizes of about 25–55 nm, and a photothermal conversion efficiency as high as 39.67%. After being adsorbed onto doxorubicin, the Bi cluster can be used directly in animal experiments. Due to the effect of enhanced permeability and retention, the probe can easily enter tumor cells. Drug release can be controlled by a near‐infrared laser and the acidic environment of tumor cells, which indicates that the combined chemo‐photothermal therapy is achieved. This work presents a new dual‐mode bio‐imaging and combined chemo‐photothermal therapeutic nanoprobe that can be applied in theragnostics for tumors.