The second near-infrared (NIR-II) fluorescence probes presents many advantages for its large Stokes-shift and low signal to noise ratio. Lanthanide doped NIR-II luminescent nanoparticles have attracted intense attention in biomedical research. Here Er³⁺ doped nanoparticles with core–shell structure was proposed. After surface modification, we got PEG modified hydrophilic NaYbF₄:Er@CaF₂ nanoparticles. The cytotoxicity test and the imaging performance in vivo experiments were carried out. Under the irradiation of 980 nm laser, the mice presented clear near-infrared imaging in vivo. So far, prominent optical properties of NaYbF₄:Er@CaF₂-PEG UCNPs has been proved, which is expected to become a new type of imaging probe in the future.

第二种近红外（NIR-II）荧光探针因其较大的斯托克斯位移和低信噪比而具有许多优势。镧系元素掺杂的NIR-II发光纳米粒子在生物医学研究中引起了广泛的关注。这里提出了具有核-壳结构的掺Er ^3+的纳米颗粒。表面改性后，得到PEG改性的亲水性NaYbF ₄：Er @ CaF ₂纳米颗粒。进行了细胞毒性试验和体内成像性能实验。在980 nm激光的照射下，小鼠体内呈现清晰的近红外成像。到目前为止，NaYbF ₄：Er @ CaF _2的突出光学性质-PEG UCNPs已被证明，有望在将来成为一种新型的成像探针。