In Vivo Fluorescence Imaging with Ag2S Quantum Dots in the Second Near‐Infrared Region

Ag 2 S quantum dots (QDs) with bright near-infrared-II fluorescence emission (around 1200 nm) and six-arm branched PEG surface coating (see scheme) were synthesized for in vivo small-animal imaging. The 6PEG-Ag 2 S QDs afforded a tumor uptake of approximately 10 % injected dose/gram, owing to a long circulation half-life of approximately 4 h. Clearance of the injected 6PEG-Ag 2 S QDs occurs mainly through the biliary pathway in mice.