Next-generation in vivo optical imaging with short-wave infrared quantum dots

Abstract

The short-wavelength infrared region (SWIR; 1000—2000 nm) provides several advantages over the visible and near-infrared regions for in vivo imaging. The general lack of autofluorescence, low light absorption by blood and tissue, and reduced scattering can render a mouse translucent when imaged in the SWIR region. Despite these advantages, the lack of a versatile emitter platform has prevented its general adoption by the biomedical research community. Here we introduce high-quality SWIR-emitting core/shell quantum dots (QDs) for the next generation of in vivo SWIR imaging. Our QDs exhibit a dramatically higher emission quantum yield (QY) than previously described SWIR probes, as well as a narrow and size-tunable emission that allows for multiplexing in the SWIR region. To demonstrate some of its capabilities, we used this imaging platform to measure the heartbeat and breathing rates in awake and unrestrained mice, as well as to quantify the metabolic turnover rates of lipoproteins in several organs simultaneously in real time in mice. Finally, we generate detailed three-dimensional quantitative flow maps of brain vasculature by intravital microscopy and visualize the differences between healthy tissue and a tumor in the brain. In conclusion, SWIR QDs enable biological optical imaging with an unprecedented combination of deep penetration, high spatial resolution, and fast acquisition speed.