摘要：Luminescent biosensing in the second nearinfrared(NIR-II) region is featured with superior spatial resolution and high penetration depth by virtue of the suppressed scattering of long-wavelength photons. Hitherto, the reported NIR-II nanoprobes are mostly based on carbon nanotubes, organic fluorophores or semiconducting quantum dots. As an alternative, trivalent lanthanide ions(Ln3+) doped nanoparticles have been emerging as a novel class of promising nanoprobes. In this review, we highlight the recent progress in the design of highly efficient Ln3+-doped NIR-II nanoparticles towards their emerging bioapplications, with an emphasis on autofluorescence-free bioimaging, sensitive bioassay, and accurate temperature sensing. Moreover, some efforts and challenges towards this rapidly expanding field are envisioned.

摘要：Polarized upconversion luminescence(UCL)of lanthanide-doped micro/nano-crystals has shown great promise in single-particle tracking and super-resolution ***,because of the spectral line broadening and multiple sites of lanthanide in upconversion particles(UCPs),the crystal-field(CF)polarization components of UCL are usually ***,we report the linearly polarized UCL in LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals with resolvable CF transition lines and a polarization degree up to *** CF levels and CF transition lines of Er^(3+),as well as their emission polarization anisotropy,are unraveled for the first time through low-temperature and high-resolution photoluminescence(PL)and UCL *** taking advantage of the well-resolved and highly-polarized CF transition lines of Er^(3+),we demonstrate the application of LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals as anisotropic UCL probes for orientation *** findings provide fundamental insights into the polarization anisotropy of UCL in lanthanide-doped single particles,thus laying a foundation for the future design of anisotropic luminescent probes towards versatile applications.

摘要：稀土掺杂的无序结构晶体具有优异的下转移和上转换发光性能,通过对材料的发光调控可使其广泛应用于各种光学和光电子学领域。稀土离子的光学性质与所处的晶体场环境密切相关,因此,使用稀土离子作为灵敏的结构探针,可以确定无序结构发光材料中稀土离子掺杂的局域结构和位置对称性;同时,通过改变稀土离子掺杂的无序结构晶体的局域位置对称性也可以进行一系列发光调控。本文首先介绍了稀土离子掺杂无序结构材料的晶体学格位对称性和光谱学格位对称性;其次,系统总结了通过改变局域结构来调控稀土离子掺杂的下转移/上转换发光的最新成果,包括组分调节和外场调节;最后,深入探讨了稀土掺杂无序结构发光材料面临的挑战和发展前景。