Unlocking near-infrared-II chemiluminescence for biomedical imaging

By arising light from relaxation of excited-state reactants, chemiluminescence avoids autofluorescence interference, thereby allowing unique benefits for in vivo imaging. As an active branch of optical imaging, no-excitation luminescence in the second near-infrared (NIR-II, 1000–1700 nm) region holds considerable potential for deep-tissue penetration and visualization of biological events by reducing light-tissue interactions. Owing to the convergence of chemiluminescence and “transparent” optical window, NIR-II chemiluminescence are poised to evolve from research tools into platforms for enhancing the precision of diagnosis. This review covers two common principles for constructing NIR-II chemiluminescence platform, including indirect NIR-II chemiluminescence via energy relay and direct NIR-II chemiluminescence through molecular engineering, and then offers a detailed discussion of these two approaches. The latest NIR-II chemiluminescence platforms capable of detecting biomarkers, including reactive oxygen species, gas signaling molecules, and enzymes overexpressed in disease diagnosis, are summarized in this review. Finally, potential optimizations in activity-based NIR-II chemiluminescence platform in the fields of analytical techniques and precision medicine are also outlined.