Antaris, A.L. et al. Nat. Commun. 8, 15269 (2017).

Imaging in the near-infrared (NIR) II region (1,000–1,700 nm) is potentially useful for deep tissue imaging, as light scattering and autofluoresence are minimized at longer wavelengths. However, probes for such imaging often suffer from poor photophysical properties, such as low quantum yields. Antaris et al. built on previous work with donor-acceptor-donor dyes that fluoresce in the NIR range to develop a bright new NIR II probe for in vivo imaging. By changing functional groups on a previously developed dye, the group produced the dye CH-4T, which, when mixed with plasma proteins in the blood, spontaneously forms brightly fluorescent supramolecular assemblies. The researchers demonstrate that the probe is useful for vascular imaging and for resolving cardiac cycles in living mice.