Li Ai-Hua, Lü Mengyun, Yang Jun, Chen Lin, Cui Xiaohong, Sun Zhijun
Department of Physics, Xiamen University, Xiamen 361005, P R China.
Dalton Trans. 2016 Apr 7;45(13):5800-7. doi: 10.1039/c6dt00237d. Epub 2016 Mar 3.
Sub-20 nm core-shell and water-soluble SrF2:Yb,Tm@CaF2:Gd heteronanoparticles with both upconversion luminescence (UCL) and magnetic resonance imaging (MRI) capabilities were designed and synthesized via a two-step hydrothermal method. In the design of the heteronanoparticles, SrF2:Yb,Tm nanoparticles with high UCL efficiency are chosen as the core material for strong UCL output; and by epitaxially coating the SrF2:Yb,Tm core particles with inert and biocompatible shells of CaF2:Gd, the core-shell heteronanoparticles are endowed with a magnetic capability (longitudinal relaxivity of 2.4 mM(-1) s(-1)) for MRI, as well as an enhancement of the near infrared (NIR) UCL by 9.2 times. The aqueous dispersion of SrF2:Yb,Tm@CaF2:Gd heteronanoparticles with a concentration of 2.6 wt% can emit NIR UCL so as to be easily detected with a fiber optical spectrometer under illumination of a 975 nm laser diode with a power density of 8.8 W cm(-2). Such a dispersion with a Gd(3+) concentration of 0.0143 mM in the shell region of the heteronanoparticles can also generate the detectable quickening of longitudinal relaxation. The results promise the strong potential of this nanomaterial for applications in bioimaging as a dual-functional probe.
通过两步水热法设计并合成了具有上转换发光（UCL）和磁共振成像（MRI）能力的亚20纳米核壳型水溶性SrF2:Yb,Tm@CaF2:Gd异质纳米粒子。在异质纳米粒子的设计中，选择具有高UCL效率的SrF2:Yb,Tm纳米粒子作为核心材料以实现强UCL输出；通过用惰性且生物相容的CaF2:Gd壳层外延包覆SrF2:Yb,Tm核心粒子，核壳型异质纳米粒子被赋予了用于MRI的磁性能（纵向弛豫率为2.4 mM(-1) s(-1)），同时近红外（NIR）UCL增强了9.2倍。浓度为2.6 wt%的SrF2:Yb,Tm@CaF2:Gd异质纳米粒子的水分散体在功率密度为8.8 W cm(-2)的975 nm激光二极管照射下可发射NIR UCL，从而易于用光纤光谱仪检测。在异质纳米粒子壳层区域中Gd(3+)浓度为0.0143 mM的这种分散体也可产生可检测到的纵向弛豫加快。这些结果表明这种纳米材料作为双功能探针在生物成像应用中具有巨大潜力。
