In this study, the core/shell/shell-structured SiO₂/YPO₄:Nd/SiO₂ composite microspheres with near-infrared luminescence property were prepared by sol-gel method. The morphology and structure of the as-prepared microspheres were observed by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and infrared spectroscopy (IR). These tests show that the composite microspheres have a sandwich structure. The diameter of the core SiO₂ microspheres is ~ 220 nm, the intermediate layer thickness of rare-earth phosphate is ~ 5 nm, and the outer SiO₂ layer is ~ 20 nm thick. The core/shell/shell microspheres are emitted at 1063 nm in the near-infrared region, which attributes to optical transparent windows of biological tissues. Meanwhile, the interaction between the composite microspheres and bovine serum albumin (BSA) was investigated. The results showed that the composite microspheres could quench the emission intensity of BSA by binding the tryptophan residues in BSA. The synthesized core/shell/shell composite microspheres may be used as near-infrared luminescence probes in the field of biological tissue imaging.

本研究采用溶胶-凝胶法制备了具有近红外发光性能的核/壳/壳结构SiO ₂ / YPO ₄：Nd / SiO ₂复合微球。通过透射电子显微镜（TEM），能量色散X射线光谱（EDX），X射线衍射（XRD）和红外光谱（IR）观察制备的微球的形态和结构。这些测试表明复合微球具有夹心结构。核心SiO ₂微球的直径约为220 nm，稀土磷酸盐的中间层厚度约为5 nm，外部SiO ₂层厚约20 nm。核/壳/壳微球在近红外区域以1063 nm的波长发射，这归因于生物组织的光学透明窗口。同时，研究了复合微球与牛血清白蛋白（BSA）之间的相互作用。结果表明，复合微球可以通过结合BSA中的色氨酸残基来猝灭BSA的发射强度。合成的核/壳/壳复合微球可用作生物组织成像领域的近红外发光探针。