Ag_2S Quantum Dot: A Bright and Biocompatible Fluorescent Nanoprobe in the Second Near-Infrared Window

摘要

Fluorescent imaging in the second near-infrared window (NIR Ⅱ, 1-1.4 μm) is appealing due to minimal autofluorescence and tissue scattering in this region, affording maximal penetration depth for deep tissue imaging with high feature fidelity. Simulations and modeling studies suggested that the fluorophores with emission between 1000 - 1320 nm (NIR Ⅱ) could significantly improve signal-to-noise ratios compared to those emitting at 850 nm (NIR Ⅰ). Recent efforts have been devoted to identifying NIR Ⅱ-emitting agents for in vivo imaging applications. Quantum dots (QDs) such as PbSe, PbS, and CdHgTe with emission in the NIR Ⅱ have been successfully developed. However, the highly toxic nature of Pb, Cd and Hg is of concern for in vivo applications. Highly biocompatible fluorescent probes that do not contain Cd, Pd or Hg in the NIR Ⅱ window between 900 and 1400 nm will facilitate biological imaging in this beneficial spectral region.