Advanced Photonics Center, Southeast University, Nanjing 210096, Jiangsu, China.
Talanta. 2013 Nov 15;116:978-84. doi: 10.1016/j.talanta.2013.08.015. Epub 2013 Aug 17.
A magnetically controllable dual-mode optical probe is demonstrated for cellular imaging with an onion-liked structure, which can exhibit both surface enhanced Raman scattering (SERS) and fluorescence signals. For obtaining such a nanoprobe, Fe3O4 nanoparticles were first encapsulated into an inner layer of silica, which were then coated with a second layer of gold nanoshell (designated as Fe3O4@SiO2@Au). By adjusting the thickness of the gold shell, the surface plasmon resonance (SPR) of Fe3O4@SiO2@Au nanoparticles can be easily tuned from visible to near-infrared (NIR) region. Afterwards, the prepared Fe3O4@SiO2@Au nanoparticles were tagged with a third layer of Raman reporters to exhibit SERS signals and further coated with an outmost layer of dye-doped silica to generate fluorescence. When being excited at different wavelengths as 515nm and 633nm, the distinct fluorescence and SERS signals can be separately observed. More interestingly, an enhanced cellular uptake of the presented nanoprobes was observed in the presence of a magnetic field, which was proved by both fluorescence and SERS images. This onion-liked multi-modal nanoplatform has great potential in bio-imaging, targeted delivery applications and biological separations.
一种具有洋葱状结构的磁控双模光学探针用于细胞成像，可同时显示表面增强拉曼散射（SERS）和荧光信号。为了获得这种纳米探针，首先将 Fe3O4 纳米粒子封装到内硅层中，然后再涂覆第二层金纳米壳（标记为 Fe3O4@SiO2@Au）。通过调整金壳的厚度，可以轻松地将 Fe3O4@SiO2@Au 纳米粒子的表面等离子体共振（SPR）从可见光调谐到近红外（NIR）区域。之后，将制备的 Fe3O4@SiO2@Au 纳米粒子标记上第三层拉曼报告分子以显示 SERS 信号，并进一步涂覆最外层掺杂染料的二氧化硅以产生荧光。当分别用 515nm 和 633nm 的不同波长激发时，可以分别观察到明显的荧光和 SERS 信号。更有趣的是，在磁场存在下观察到所提出的纳米探针的细胞摄取增强，这通过荧光和 SERS 图像得到了证实。这种洋葱状的多模态纳米平台在生物成像、靶向递药应用和生物分离方面具有巨大的潜力。
