Near‐Infrared‐II Molecular Dyes for Cancer Imaging and Surgery

Abstract

Fluorescence bioimaging affords a vital tool for both researchers and surgeons to molecularly target a variety of biological tissues and processes. This review focuses on summarizing organic dyes emitting at a biological transparency window termed the near‐infrared‐II (NIR‐II) window, where minimal light interaction with the surrounding tissues allows photons to travel nearly unperturbed throughout the body. NIR‐II fluorescence imaging overcomes the penetration/contrast bottleneck of imaging in the visible region, making it a remarkable modality for early diagnosis of cancer and highly sensitive tumor surgery. Due to their convenient bioconjugation with peptides/antibodies, NIR‐II molecular dyes are desirable candidates for targeted cancer imaging, significantly overcoming the autofluorescence/scattering issues for deep tissue molecular imaging. To promote the clinical translation of NIR‐II bioimaging, advancements in the high‐performance small molecule–derived probes are critically important. Here, molecules with clinical potential for NIR‐II imaging are discussed, summarizing the synthesis and chemical structures of NIR‐II dyes, chemical and optical properties of NIR‐II dyes, bioconjugation and biological behavior of NIR‐II dyes, whole body imaging with NIR‐II dyes for cancer detection and surgery, as well as NIR‐II fluorescence microscopy imaging. A key perspective on the direction of NIR‐II molecular dyes for cancer imaging and surgery is also discussed.

Multiplexed NIR‐II Probes for Lymph Node‐Invaded Cancer Detection and Imaging‐Guided Surgery

“…Although the peak emission of donor–acceptor–donor (D‐A‐D) dyes and the tail emission of cyanine dyes can be both used for NIR‐II imaging, the benefit of NIR‐II imaging is better realized in the NIR‐IIb sub‐window (>1500 nm), where light can penetrate nearly all tissues . Imaging in the NIR‐IIb window can minimize photon scattering and simultaneously avoid high absorbance by water, affording high resolution of mouse vasculature at depths of several millimeter in the brain or other tissues .…”

Design of AIEgens for near-infrared IIb imaging through structural modulation at molecular and morphological levels

“…F luorescence imaging in the second near-infrared region (NIR-II, 1000-1700 nm) enables direct visualization and real-time feedback of deep biological structures with a miraculous degree of clarity than NIR-I (800-900 nm) due to further suppressed photon scattering and minimized autofluorescence [1][2][3][4][5][6][7] . Simulation and experimental results have revealed that the imaging performance in term of spatial and temporal resolution and penetration depth could be further enhanced by the NIR-IIb (1500-1700 nm) fluorophores due to almost zero autofluorescence and much lower photo scattering [8][9][10] .…”

Prototypic Heptamethine Cyanine Incorporating Nanomaterials for Cancer Phototheragnostic

“…Nevertheless, ICG has a low photostability and a low fluorescence quantum yield . Such has motivated the encapsulation of other heptamethine cyanines (e.g., IR780, IR808, IR825) that exhibit improved optical properties in nanostructures for cancer phototheragnostic …”