title: Nanoplasmonic Upconverting Nanoparticles as Orientation Sensors for Single Particle Microscopy.
abstract: 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 Imax/Iminratio of up to 2.02. Both the orientation dependence and Imax/Iminare 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 10-2μm2s-1.
authors.affiliation: Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA.
authors.forename: Kory K
authors.initials: KK
authors.lastname: Green
authors.affiliation: Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA.
authors.forename: Janina
authors.initials: J
authors.lastname: Wirth
authors.affiliation: Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA. sflim@ncsu.edu.
authors.forename: Shuang F
authors.initials: SF
authors.lastname: Lim