A mesoporous silica-based MRI/NIR-II fluorescence bimodal nanoprobe for precision detection and surgical navigation of sentinel lymph node metastasis.

Precise detection of sentinel lymph node (SLN) metastasis is critical for accurate cancer staging and effective surgical navigation. In this study, we developed a high-performance magnetic resonance imaging (MRI)/near-infrared (NIR)-II fluorescence imaging nanoplatform by integrating the NIR dye IR820 and the gadolinium-based MRI contrast agent (GdL) into mesoporous silica nanoparticles (MSNs) using bovine serum albumin (BSA) as the functional component. This nanoplatform exhibits strong NIR-II fluorescence tail emission and high longitudinal relaxivity, enabling dual-modality imaging for the diagnosis of primary tumors and metastatic lymph nodes, as well as NIR-II fluorescence-guided surgery (FGS). Within this system, BSA not only serves as a structural stabilizer but also significantly enhances IR820 fluorescence emission and improves GdL relaxivity. Notably, two types of surface-functionalized MSNs, amine- and thiol-modified, were systematically compared, and the thiol-modified MSNs exhibited superior imaging performance, including a red-shifted absorption peak and markedly enhanced NIR-II fluorescence emission. In vitro and in vivo experiments confirmed that the dual-modality nanoprobe accumulated efficiently in tumors and SLNs, enabling high-sensitivity MRI localization and high-resolution NIR-II fluorescence imaging of metastatic lesions. Overall, this study presents a surface-engineering strategy to enhance the imaging performance of MRI/NIR-II nanoprobes, offering a promising approach for accurate diagnosis of lymph node metastasis and real-time FGS.