Nanoprobe Based on Novel NIR‐II Quinolinium Cyanine for Multimodal Imaging

NIR-II imaging has the advantages of high sensitivity, spatiotemporal resolution, and high penetration depth, thereby serving as a potential alternative to conventional imaging methods. Herein, a novel NIR-II dye IR-1010 (λ_ex/λ_em = 1010/1058 nm) is reported with high quantum yield (3.08%) and good stability, by incorporating p-methoxyphenyl groups into a quinolinium cyanine dye. Then a multifunctional nanoprobe, termed IUFP NPs, is developed by the incorporation of upconversion (UC) nanoparticles (NPs), perfluoro-15-crown-5-ether (PFCE), and IR-1010, to display the novel performance of multimodal imaging. Under the single-wavelength excitation (980 nm), IUFP NPs simultaneously emit the NIR-II fluorescence of IR-1010 and visible UC luminescence of UCNPs, and thus realize the UC imaging for cells, and NIR-II fluorescence/photoacoustic/¹⁹F magnetic resonance imaging for blood vessels, lymph nodes and tumor in mice. This work affords a novel approach to NIR-II dyes and a general strategy for the design of multimodal imaging probes.