A novel theranostic agent based on porous bismuth nanosphere for CT imaging-guided combined chemo-photothermal therapy and radiotherapy.

In recent years, multifunctional bio-nanomaterials applied as theranostic agents in cancer diagnosis and therapy have attracted great attention due to their powerful functionality. Here, for the first time, we develop a novel theranostic agent based on porous bismuth (pBi) nanospheres for tumor imaging and combined chemotherapy, photothermal therapy (PTT) and radiotherapy (RT). The pBi nanospheres have good biocompatibility due to a polyvinylpyrrolidone (PVP) coating, and have a high photothermal conversion efficiency (η = 48.5%) for PTT. The pBi nanospheres could be used as a radiosensitizer to trigger X-ray deposition and acted as an excellent computed tomography (CT) imaging contrast agent owing to the Bi content. The pBi nanospheres can also be used as a carrier for drug delivery due to their porous structures. Moreover, the thermal effect of the as-produced PTT substantially enhanced the release of doxorubicin (DOX) for chemotherapy, resulting in a synergistic therapeutic effect for complete tumor removal. Meanwhile, treatment with pBi/DOX nanospheres caused no obvious toxicity. Therefore, these multi-functional pBi nanospheres, fabricated by a unique method, have a great promise for application in CT imaging-guided synergetic cancer therapy.