A new strategy for synthesizing AgInS2 quantum dots emitting brightly in near-infrared window for in vivo imaging

A new strategy for fabricating water-dispersible AgInS2 quantum dots (QDs) with bright near-infrared (NIR) emission is demonstrated. A type of multidentate polymer (MDP) was synthesized and utilized as a compact capping ligand for the AgInS2 QDs. Using silver nitrate, indium acetate and sulfur–hydrazine hydrate complex as the precursors, MDP-capping AgInS2 QDs were synthesized in aqueous solution at room temperature. Characterization indicates that the MDP-capping AgInS2 QDs are highly photoluminescent in NIR window and possess good photostability. Also, the QDs are stable in different media and have low cytotoxicity. Nude mice photoluminescence imaging shows that the MDP-capping AgInS2 QDs can be well applied to in vivo imaging. These readily prepared NIR fluorescent nanocrystals have huge potential for biomedical applications.