Au-Doped Ag Te Quantum Dots with Bright NIR-IIb Fluorescence for In Situ Monitoring of Angiogenesis and Arteriogenesis in a Hindlimb Ischemic Model

Fluorescence located in 1500-1700 nm (denoted as the near-infrared IIb window, NIR-IIb) has drawn great interest for bioimaging, owing to its ultrahigh tissue penetration depth and spatiotemporal resolution. Therefore, NIR-IIb fluorescent probes with high photoluminescence quantum yield (PLQY) and stability along with high biocompatibility are urgently pursued. Herein, a novel NIR-IIb fluorescent probe of Au-doped Ag Te (Au:Ag Te) quantum dots (QDs) is developed via a facile cation exchange method. The Au dopant concentration in the Ag Te QDs is tunable from 0% to 10% by controlling the ratio of supplied Au precursor to Ag Te QDs, resulting in a wide range of PL emission in the NIR-IIb window and a much-enhanced PL intensity. After surface modification, the Au:Ag Te QDs possess bright NIR-IIb emission, high colloidal stability and photostability, and decent biocompatibility. Further, in vivo monitoring of the process of angiogenesis and arteriogenesis in an ischemic hindlimb is successfully performed.