Fluorescent Ag–In–S/ZnS Quantum Dots for Tumor Drainage Lymph Node Imaging In Vivo

Tumor drainage lymph node imaging is crucial for oncological surgery, where the complete dissection of sentinel lymph nodes could largely prevent/delay recurrence. However, current commercially used imaging reagents distinguish the lymph nodes by staining them dark, which might be seriously interfered with by blood and other tissues. Herein, we reported fluorescent Ag–In–S/ZnS quantum dots (AIS/ZnS QDs) with red emission for fast tumor drainage lymph node imaging. AIS/ZnS QDs were synthesized by solution reaction and then dispersed in poly(vinyl pyrrolidone) for in vivo applications. AIS/ZnS QDs were well dispersed in water with hydrodynamic radii of 295 nm, suitable for lymph node imaging. The fluorescent imaging capability of AIS/ZnS QDs was first established after subcutaneous injection in mice. AIS/ZnS QDs could migrate to sentinel lymph nodes after the interdermal injection to the extremities. Tumor drainage lymph node imaging was achieved within 10 min upon intratumoral injection to H460 tumor-bearing mice. However, intravenous injection did not lead to tumor uptake of AIS/ZnS QDs. The fast and efficient migration of AIS/ZnS QDs into tumor drainage lymph nodes resulted in AIS/ZnS QDs being a high-performance imaging reagent for tumor drainage lymph nodes in vivo.