title: Confocal, three-dimensional tracking of individual quantum dots in high-background environments.
abstract: We demonstrate a custom confocal fluorescence-microscope that is capable of tracking individual quantum dots undergoing three-dimensional Brownian motion (diffusion coefficient approximately 0.5 microm(2)/s) in environments with a signal-to-background ratio as low as 2:1, significantly worse than observed in a typical cellular environment. By utilizing a pulsed excitation source and time-correlated single photon counting, the time-resolved photon stream can be used to determine changes in the emission lifetime as a function of position and positively identify single quantum dots via photon-pair correlations. These results indicate that this microscope will be capable of following protein and RNA transport throughout the full three-dimensional volume of a live cell for durations up to 15 s.
authors.affiliation: Center for Integrated Nanotechnologies (MPA-CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Wells
authors.forename: Guillaume A
authors.initials: GA
authors.lastname: Lessard
authors.forename: James H
authors.initials: JH
authors.lastname: Werner
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D036103:Nanotechnology; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C058667:cadmium selenide; C031238:zinc sulfide