Near-infrared II fluorescence imaging

Near-infrared II (NIR-II) fluorescence imaging is a non-invasive optical technique that employs fluorophores emitting in the 1000-1700 nm wavelength window to achieve superior deep-tissue penetration, reduced photon scattering, minimal tissue autofluorescence, and high spatiotemporal resolution compared to visible light or NIR-I (700-950 nm) imaging.[1][2][3] This enables real-time visualization of anatomical structures like blood vessels, lymph nodes, and tumors in vivo, with penetration depths up to several centimeters and resolutions down to ~10-24 µm.[1][3][4] Common probes include silver sulfide quantum dots (Ag2S QDs), single-walled carbon nanotubes (SWCNTs), rare earth nanoparticles, and small molecules like indocyanine green (ICG) with NIR-II emission tails, offering high photostability, biocompatibility, and tunability for applications in cancer diagnostics, image-guided surgery, and drug delivery monitoring.[1][4][5] NIR-II imaging provides higher signal-to-background ratios and supports quantitative analysis of biological processes, such as reactive oxygen species or pH changes, outperforming traditional modalities like PET-CT or MRI in temporal resolution for small animal models.[3][4] Challenges include water absorption in parts of the NIR-II range and the need for specialized InGaAs detectors, though it holds promise for clinical translation in oncology and beyond.[1][2][6]

Other names

NIR-II fluorescence imagingsecond near-infrared fluorescence imagingNIR-II bioimaging