Advances in Lanthanide‐Based NIR‐IIb Probes for In Vivo Biomedical Imaging

Abstract The past decades have witnessed the significant development and practical interest of in vivo biomedical imaging technologies and optical materials in the second‐near infrared (NIR‐II, 1000–1700 nm) window. Imaging with the extended emission wavelength toward the long‐wavelength end (NIR‐IIb, 1500–1700 nm) further offers micrometer imaging resolution and centimeter tissue penetration depth by taking advantage of the much‐reduced photon scattering and near‐zero tissue autofluorescence background, which have become a very hot research area. This review focuses on the recent advances in the development of lanthanide‐based NIR‐IIb probes for in vivo biomedical applications. The progress including ratiometric imaging, multiplexed imaging for wide‐field and microscopy, lifetime multiplexing and sensing, persistent luminescence, and multimodal imaging is summarized. Challenges and future directions concerning the investigation of the photophysical and photochemical properties of NIR‐IIb probes, the selection of near‐infrared cameras as well as the potential extension of the NIR‐IIb imaging sub‐window are pointed out. This review will inspire readers who have a strong interest in developing optical imaging technology and long‐wavelength fluorescence probes for high‐contrast in vivo biomedical applications.