Macrophages-mediated tumor accumulation and deep penetration of bismuth/manganese biomineralized nanoparticles for enhanced radiotherapy

Radiotherapy(RT) is a widely used cancer treatment, and the use of metal-based nano-radiotherapy sensitizers has shown promise in enhancing its efficacy. However, efficient accumulation and deep penetration of these sensitizers within tumors remain challenging. In this study, we present the development of bismuth/manganese biomineralized nanoparticles(Bi Mn/BSA) with multiple radiosensitizing mechanisms, including high atomic number element-mediated radiation capture, catalase-mimic oxygenation,and activation of the stimulator of interferon genes(STING) pathway. Significantly, we demonstrate that low-dose RT induces the recruitment of macrophages and subsequent upregulation of Matrix metalloproteinases(MMP)-2 and MMP-9 that degrade the extracellular matrix(ECM). This dynamic process facilitates the targeted delivery and deep penetration of Bi Mn/BSA nanoparticles within tumors, thereby enhancing the effectiveness of RT. By combining low-dose RT with Bi Mn/BSA nanoparticles, we achieved complete suppression of tumor growth in mice with excellent biocompatibility. This study provides a novel and clinically relevant strategy for targeted nanoparticle delivery to tumors, and establishes a safe and effective sequential radiotherapy approach for cancer treatment. These findings hold great promise for improving the outcomes of RT and advancing the field of nanomedicine in cancer therapy.