An albumin-based NIR-II fluorescence/MRI bimodal imaging probe for precise diagnosis of lymph node tumor metastasis

Tumor metastasis is the primary cause behind the majority of cancer deaths, highlighting the urgent need for effective diagnostic and therapeutic strategies. In this paper, we rationally integrate a near-infrared (NIR) fluorescence dye IR820 and a magnetic resonance imaging (MRI) contrast agent GdL into bovine serum albumin (BSA) to construct a novel albumin-based NIR-II fluorescence/MRI bimodal imaging probe for precise diagnosis of tumor and metastatic lymph nodes (LNs). The bimodal imaging probe (BSA-IR820-GdL) could be quickly and effortlessly prepared by simply mixing the three components in accordance with a certain mix ratio. Compared to any single molecule, the bimodal imaging probe not only integrates NIR-II fluorescence and magnetic characteristics into one single nanoscale platform, but also can extend the fluorescence emission of IR820 from the NIR-I region to the NIR-II window and significantly enhance the relaxivity of GdL. Using NIR-II fluorescence and MR imaging technologies, we have successfully achieved dual-modality imaging of tumors and metastatic LNs in a lymph node metastasis mouse model. This study provides a valuable tool for preoperative tumor assessment and intraoperative surgical navigation.