Particle Technology Laboratory, Institute of Process Engineering, Institute of Energy Technology Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland.
ACS Nano. 2012 May 22;6(5):3888-97. doi: 10.1021/nn205035p. Epub 2012 May 4.
Nanophosphors are light-emitting materials with stable optical properties that represent promising tools for bioimaging. The synthesis of nanophosphors, and thus the control of their surface properties, is, however, challenging. Here, flame aerosol technology is exploited to generate Tb-activated Y(2)O(3) nanophosphors (∼25 nm) encapsulated in situ by a nanothin amorphous inert SiO(2) film. The nanocrystalline core exhibits a bright green luminescence following the Tb(3+) ion transitions, while the hermetic SiO(2)-coating prevents any unspecific interference with cellular activities. The SiO(2)-coated nanophosphors display minimal photobleaching upon imaging and can be easily functionalized through surface absorption of biological molecules. Therefore, they can be used as bionanoprobes for cell detection and for long-term monitoring of cellular activities. As an example, we report on the interaction between epidermal growth factor (EGF)-functionalized nanophosphors and mouse melanoma cells. The cellular uptake of the nanophosphors is visualized with confocal microscopy, and the specific activation of EGF receptors is revealed with biochemical techniques. Altogether, our results establish SiO(2)-coated Tb-activated Y(2)O(3) nanophosphors as superior imaging tools for biological applications.
纳米荧光粉是具有稳定光学性能的发光材料，它们是生物成像的有前途的工具。然而，纳米荧光粉的合成，也就是对其表面性能的控制，具有挑战性。在这里，利用火焰气溶胶技术生成了 Tb 激活的 Y(2)O(3)纳米荧光粉（约 25nm），并原位包覆了一层纳米级的非晶惰性 SiO(2)薄膜。纳米晶核表现出明亮的绿色荧光，这是 Tb(3+)离子跃迁的结果，而密封的 SiO(2)涂层可以防止任何与细胞活动无关的干扰。SiO(2)涂层的纳米荧光粉在成像时几乎不会发生光漂白，并且可以通过表面吸收生物分子很容易地进行功能化。因此，它们可以用作生物纳米探针，用于细胞检测和长期监测细胞活动。例如，我们报告了表皮生长因子（EGF）功能化的纳米荧光粉与小鼠黑色素瘤细胞之间的相互作用。通过共聚焦显微镜观察到纳米荧光粉的细胞摄取，并通过生化技术揭示了 EGF 受体的特异性激活。总之，我们的结果确立了 SiO(2)包覆的 Tb 激活的 Y(2)O(3)纳米荧光粉作为生物应用的优越成像工具。
