Multiplexed NIR-II Probes for Lymph Node-Invaded Cancer Detection and Imaging-Guided Surgery.

Tumor-lymph node (LN) metastasis is the dominant prognostic factor for tumor staging and therapeutic decision-making. However, concurrently visualizing metastasis and performing imaging-guided lymph node surgery is challenging. Here, a multiplexed-near-infrared-II (NIR-II) in vivo imaging system using nonoverlapping NIR-II probes with markedly suppressed photon scattering and zero-autofluorescence is reported, which enables visualization of the metastatic tumor and the tumor metastatic proximal LNs resection. A bright and tumor-seeking donor-acceptor-donor (D-A-D) dye, IR-FD, is screened for primary/metastatic tumor imaging in the NIR-IIa (1100-1300 nm) window. This optimized D-A-D dye exhibits greatly improved quantum yield of organic D-A-D fluorophores in aqueous solutions (≈6.0%) and good in vivo performance. Ultrabright PbS/CdS core/shell quantum dots (QDs) with dense polymer coating are used to visualize cancer-invaded sentinel LNs in the NIR-IIb (>1500 nm) window. Compared to clinically used indocyanine green, the QDs show superior brightness and photostability (no obvious bleaching even after continuous laser irradiation for 5 h); thus, only a picomolar dose is required for sentinel LNs detection. This combination of dual-NIR-II image-guided surgery can be performed under bright light, adding to its convenience and appeal in clinical use.