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Updated: Jun 27, 2026

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles
Published on: October 1, 2014
Confocal, three-dimensional tracking of individual quantum dots in high-background environments
Nathan P Wells1, Guillaume A Lessard, James H Werner
1Center for Integrated Nanotechnologies (MPA-CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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.
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