Self-Assembled Hybrid Nanocomposites for Multimodal Imaging-Guided Photothermal Therapy of Lymph Node Metastasis

Multimodal imaging-guided therapy holds great potential for precise theranostics of cancer metastasis. However, imaging agents enabling the convergence of complementary modalities with therapeutic functions to achieve perfect theranostics have been less exploited. This study reports the construction of a multifunctional nanoagent (FIP-Tc-99m) that comprises Fe3O4 for magnetic resonance imaging, radioactive Tc-99m for single-photon-emission computed tomography, and IR-1061 to serve for the second near-infrared fluorescence imaging, photoacoustic imaging, and photothermal therapy treatment of cancer metastasis. The nanoagent possessed superior multimodal imaging capability with high sensitivity and resolution attributing to the complement of all the imaging modalities. Moreover, the nanoagent showed ideal photothermal conversion ability to effectively kill tumor cells at low concentration and power laser irradiation. In the in vivo study, FIP-Tc-99m confirmed the fast accumulation and clear delineation of metastatic lymph nodes within 1 h after administration. Attributing to the efficient uptake and photothermal conversion, FIP-Tc-99m could raise the temperature of metastatic lymph nodes to 54 degrees C within 10 min laser irradiation, so as to facilitate tumor cell ablation. More importantly, FIP-Tc-99m not only played an active role in suppressing cancer growth in metastatic lymph nodes with high efficiency but also could effectively prevent further lung metastasis after resection of the primary tumor. This study proposes a simple but effective theranostic approach toward lymph node metastasis.