An RGD peptide actively targeting nanoprobe with enhanced tumor accumulation for complementary magnetic resonance imaging/NIR-II fluorescence imaging.

Accurate visualization of tumor lesions with high contrast and well-defined margins remains a major challenge for preoperative evaluation and intraoperative navigation. Conventional single-modal contrast agents mainly rely on passive accumulation, which often suffers from limitations in terms of sensitivity, specificity and tumor uptake, as well as short circulation time in vivo. Therefore, it is necessary to develop high-performance multi-modal nanoprobes with active-targeting ability. Here, we develop an RGD-mediated active-targeted imaging nanoprobe based on lanthanide nanoparticles with a core-shell structure (NaGdF4:Er,Yb@NaGdF4:Yb,Nd), followed by in situ growth of a mesoporous SiO2 shell and surface functionalization with DSPE-PEG2000-RGD to form the nanoprobe (abbreviated as DSR) for achieving molecular targeting of integrin αvβ3 on tumor vascular endothelial cells. Under 808 nm excitation, DSR exhibits intense near-infrared IIb (NIR-IIb) emission at 1525 nm, markedly improving the contrast and margin delineation of in vivo tumor imaging. Importantly, the presence of Gd3+ further endows the nanoprobe with T1-weighted magnetic resonance imaging (MRI) contrast, providing complementary anatomical information for tumor localization. With good biocompatibility, DSR can be used for actively targeted NIR-II fluorescence/T1-MRI dual-modal imaging of breast cancer, providing a promising tool for image-guided surgery.