Developing suitable contrast agents is essential for multiplexed optical coherence tomography (OCT), which allows simultaneous imaging of different biomarkers, cells and flows in living subjects. However, few OCT contrast agents have shown multiplexing capability, especially in the second near infrared (NIR-II) window. Here we demonstrate that using gold nanobipyramds as OCT contrast agents, two separate lymph flows can be visualized simultaneously in a live mouse in the NIR-II window. We concurrently traced lymph flows draining from a melanoma tumor and peritumoral tissue upstream of the melanoma, showing these flows exhibit distinct drainage patterns and merge into the same lymph node.
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