Green Kory K, Wirth Janina, Lim Shuang F
Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA.
Sci Rep. 2017 Apr 10;7(1):762. doi: 10.1038/s41598-017-00869-3.
We showed that the anisotropic disk shape of nanoplasmonic upconverting nanoparticles (NP-UCNPs) creates changes in fluorescence intensity during rotational motion. We determined the orientation by a three-fold change in fluorescence intensity. We further found that the luminescence intensity was strongly dependent on the particle orientation and on polarization of the excitation light. The luminescence intensity showed a three-fold difference between flat and on-edge orientations. The intensity also varied sinusoidally with the polarization of the incident light, with an I/I ratio of up to 2.02. Both the orientation dependence and I/I are dependent on the presence of a gold shell on the UCNP. Because the fluorescence depends on the NP's orientation, the rotational motion of biomolecules coupled to the NP can be detected. Finally, we tracked the real-time rotational motion of a single NP-UCNP in solution between slide and coverslip with diffusivity up to 10 μms.
我们表明，纳米等离子体上转换纳米粒子（NP-UCNPs）的各向异性盘状形状在旋转运动过程中会引起荧光强度的变化。我们通过荧光强度的三倍变化来确定其取向。我们进一步发现，发光强度强烈依赖于粒子取向和激发光的偏振。发光强度在平躺取向和边缘取向之间显示出三倍的差异。强度还随入射光的偏振呈正弦变化，I/I 比高达 2.02。取向依赖性和 I/I 都取决于 UCNP 上金壳的存在。由于荧光取决于纳米粒子的取向，因此可以检测与纳米粒子偶联的生物分子的旋转运动。最后，我们追踪了溶液中单个 NP-UCNP 在载玻片和盖玻片之间的实时旋转运动，其扩散率高达 10 μms。
