Shortwave infrared (SWIR, 1000-2000 nm) imaging has emerged as an ideal window for multiplexed imaging at the mammalian level. However, this technology remains largely limited by the lack of a highly tunable "molecular scaffold core", which allows for the SWIR dye library to simultaneously meet high brightness, minimal cross-talk, and laser-compatible absorption. Herein, we introduce a diversified quinolinium-based "scaffold core" for the generation of the SWIR dye library, allowing excitation-matchable multiplexed imaging for decoding spatiotemporal interactions. This quinolinium domain enables establishing a series of SWIR heptamethine cyanines spanning maximum absorption wavelengths from 975 to 1046 nm. Among them, QC7-NEt2 and QC7-CN exhibit high brightness and orthogonal excitation at 980 or 1064 nm, matching well the accessible lasers. Using the orthogonal dye pair, we are able to conduct two- and even three-channel excitation-matchable multiplexed imaging with minimal cross-talk for decoding spatiotemporal interactions. These dyes demonstrated dynamic, high-resolution visualization of vasculature, lymph, and intestinal systems, especially for studying the interaction between deep-tissue organs and the surrounding vasculature networks. This study provides a full demonstration of our strategy in molecular design and streamlined SWIR dye discovery to push the limits of biological imaging in basic life science and clinical applications.
Yao et al. (Mon,) studied this question.