Abstract:

Fluorescence encoding and in vivo multiplexed imaging with dual-dimensions of excitation and emission are proposed. A series of second near-infrared（NIR-II， 1000—1700 nm） fluorescent probes［ α-NaYbF₄∶8%Tm@NaYbF₄@NaYF₄（Yb/Tm）， α-NaYbF₄∶2%Er@NaYbF₄@NaYF₄（Yb/Er） and β-NaErF₄@NaYF₄（Er@Y）］ were developed for triple-channel in vivo imaging. Among them， Yb/Tm nanoparticles can emit 1640 nm long-wave second near-infrared fluorescence（NIR-II-L， 1500—1900 nm） under 915 nm laser excitation while no fluorescence signal can be detected under 808 nm excitation. Yb/Er can emit NIR-II-L fluorescence at 1532 nm under excitation of 915 nm laser while no fluorescence signal can be detected under 808 nm excitation. In contrast， Er@Y nanoparticles excited by an 808 nm laser can emit NIR-II-L fluorescence at 1525 nm， while a very weak signal can be detected under the excitation of 915 nm. The design of rare earth core-shell nanostructures successfully enhances the fluorescence intensity by 216 times. Under different power density excitations， the nanoparticles still maintain excellent optical properties of independent excitation/emission. Based on the unique optical properties of these nanoparticles， optical encoding and in vivo high-resolution detection with three channels have been achieved， providing new tools and solutions for optical information storage and in vivo multiplexed analysis.

Key words: Rare earth fluorescent probe, Second near-infrared window, In vivo imaging, Multiplexed imaging