Fluorescence Imaging In Vivo at Wavelengths beyond 1500 nm

TL;DR

This paper demonstrates the use of semiconducting single-walled carbon nanotubes for high-resolution in vivo fluorescence imaging in the long-wavelength NIR-IIb window (1500-1700 nm), enabling detailed visualization of blood vessels and tumor imaging.

Contribution

It introduces a novel imaging agent for NIR-IIb imaging, extending the wavelength range for in vivo optical imaging beyond 1500 nm.

Findings

Resolved 3-4 μm blood vessels at 3 mm depth

Mapped blood flow in multiple vessels simultaneously

Enabled tumor imaging in live mice

Abstract

Compared to imaging in the visible and near-infrared regions below 900 nm, imaging in the second near-infrared window (NIR-II, 1000-1700 nm) is a promising method for deep-tissue high-resolution optical imaging in vivo mainly due to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single-walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long-wavelength NIR region (1500-1700 nm, NIR-IIb). With this imaging agent, 3-4 um wide capillary blood vessels at a depth of about 3 mm could be resolved. Meanwhile, the blood-flow speeds in multiple individual vessels could be mapped simultaneously. Furthermore, NIR-IIb tumor imaging of a live mouse was explored. NIR-IIb imaging can be generalized to a wide range of fluorophores emitting at up to 1700 nm for high-performance in vivo optical imaging.