Dual-Wavelength Comparative Imaging Based on a Novel NIR-II/IIb Emissive Rare Earth-Doped Nanoparticle

The second near-infrared biological window two (NIR-II, 1000-1700 nm) imaging has made remarkable achievements in fluorescence imaging of diseases. Here, this work takes advantage of the rich spectral properties of rare-earth doped nanoparticles (RENPs) and their capability to present multiple emission peaks in different luminescence regions simultaneously; novel RENPs are synthesized that have emission peaks in the NIR-II1000nm (1000-1300 nm) region and enhanced emission in the NIR-IIb (1500-1700 nm) window and are named as NEU-RENPs. These RENPs with new compositions enable a fair comparison to evaluate their imaging performance in NIR-II1000nm and NIR-IIb regions under the same conditions. The imaging abilities of the resulted nanoparticles in NIR-II1000 nm and NIR-IIb regions are investigated systematically for local blood vessels, tumor vessels, acute inflammatory vessels, arterial thrombosis, cerebrovascular inflammation, and brain injury models. The results indicate that imaging of NIR-IIb shows higher resolution and sensitivity than that of NIR-II1000nm, and it has a stronger ability to accurately distinguish normal and pathological tissues. Interestingly, the fuzzy image of NIR-II1000nm reveals more information about the background structure of the target, which is difficult to be achieved in NIR-IIb imaging. The results prove NEU-RENPs based NIR-IIb imaging is preferable for biomedical applications.