Organelle tracking in a living cell with microsecond time resolution and nanometer spatial precision

Xiaolin Nan, Peter A. Sims, X. Sunney Xie

Research output: Contribution to journalArticlepeer-review

139 Scopus citations


The study of cellular processes such as organelle transport often demands particle tracking with microsecond time-resolution and nanometer spatial precision, posing significant challenges to existing tracking methods. Here, we have developed a novel strategy for two-dimensional tracking of gold nanoparticles (GNPs) with 25 μs time resolution and ∼1.5 nm spatial precision, by using a quadrant photodiode to record the positions of GNPs in an objective-type dark-field microscope. In combination with a feedback loop, this technique records long, high time-resolution and spatial precision trajectories of endocytosed GNPs transported by the molecular motors kinesin and dynein in a living cell. In the full range of organelle velocities (0-8 μm s -1), we clearly resolve the individual 8 nm steps of cargoes carried by kinesin, and the 8, 12, 16, 20, and 24 nm steps of those carried by dynein. These experiments yield new information about molecular motor stepping in living cells.

Original languageEnglish (US)
Pages (from-to)707-712
Number of pages6
Issue number5
StatePublished - Apr 4 2008
Externally publishedYes


  • Dark-field microscopy
  • Gold nanoparticles
  • Motor protein
  • Organelle transport
  • Particle tracking

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry


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