Bismuth-based nanomaterials with enhanced radiosensitivity for cancer diagnosis and treatment

Radiotherapy is one of the most common and effective clinical treatments for tumors, but how to reduce its side effects to achieve better therapeutic outcomes remains a significant challenge. As a heavy metal, bismuth (Bi) is low-cost, safe, and possesses a high X-ray attenuation coefficient, offering new opportunities to overcome these limitations. With recent advances in nanotechnology and nanomedicine, Bi-based nanoradiosensitizers have been extensively explored for enhancing tumor radiosensitization to achieve advanced diagnosis and treatment by taking advantage of their ease of preparation and modification, high stability, low cost, and excellent biocompatibility. However, the use of Bi-based nanoradiosensitizers remains in the early stages of clinical translation. In this review, we summarize the mechanisms of interaction between X-ray and Bi-based nanoradiosensitizers, discuss smart preparation and modification strategies for achieving enhanced radiotherapy sensitization effects, address material safety and biodistribution, and outline recent research advances in radiotherapy-based synergistic diagnosis and treatment. Finally, we will discuss the challenges and research priorities facing Bi-based nanoradiosensitizers to advance their clinical application development.