Rigid and Photostable Shortwave Infrared Dye Absorbing/Emitting beyond 1200 nm for High-Contrast Multiplexed Imaging

Area of Science:

• Biomedical Optics
• Organic Chemistry
• Medical Imaging

Background:

• The shortwave infrared (SWIR) spectral region (>1200 nm) offers superior tissue penetration for biomedical applications.
• Existing fluorochromes often lack optimal properties for deep tissue imaging and multiplexing.

Purpose of the Study:

• To develop a novel fluorochrome scaffold for efficient biomedical exploitation of the SWIR region.
• To evaluate the performance of the new fluorochrome in vivo for diagnostic and surgical imaging.

Main Methods:

• Synthesis of a novel tetra-benzannulated xanthenoid fluorochrome (EC7).
• Characterization of EC7's optical properties (absorption, emission, molar absorptivity, photostability).
• Demonstration of EC7 in high-contrast dual-channel intraoperative and three-channel in vivo bioimaging.

Main Results:

• EC7 absorbs/emits maximally at 1204/1290 nm with high molar absorptivity (3.91 × 10^5 cm^-1 M^-1).
• EC7 exhibits high transparency (400-900 nm), photobleaching resistance, and structural rigidity.
• Successful in vivo imaging of the hepatobiliary system, intestine, stomach, and vasculature was achieved.

Conclusions:

• EC7 is a benchmark fluorochrome for the biomedical application of SWIR imaging beyond 1200 nm.
• Its properties facilitate high-contrast multiplexing and in vivo bioimaging for diagnosis and surgery.