Single-particle tracking

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AliAlamerr

title: "Single-particle tracking" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["laboratory-techniques"] description: "AliAlamerr" topic_path: "general/laboratory-techniques" source: "https://en.wikipedia.org/wiki/Single-particle_tracking" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

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::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/5f/Singleparticletracking.svg" caption="Principle of single-particle tracking: The rectangles represent frames from an image acquisition at times ''t'' = 0, 1, 2, ... The tracked particles are represented as red circles, and in the last frame, the reconstructed trajectories are shown as blue lines"] ::

Single-particle tracking (SPT) is the observation of the motion of individual particles within a medium. The coordinates time series, which can be either in two dimensions (x, y) or in three dimensions (x, y, z), is referred to as a trajectory. The trajectory is typically analyzed using statistical methods to extract information about the underlying dynamics of the particle. These dynamics can reveal information about the type of transport being observed (e.g., thermal or active), the medium where the particle is moving, and interactions with other particles. In the case of random motion, trajectory analysis can be used to measure the diffusion coefficient.

Applications

In life sciences, single-particle tracking is broadly used to quantify the dynamics of molecules/proteins in live cells (of bacteria, yeast, mammalian cells and live Drosophila embryos). It has been extensively used to study the transcription factor dynamics in live cells. This method has been extensively used in the last decade to understand the target-search mechanism of proteins in live cells. It addresses fundamental biological questions such as how a protein of interest finds its target in the complex cellular environment? how long does it take to find its target site for binding? what is the residence time of proteins binding to DNA? Furthermore, exogenous particles are employed as probes to assess the mechanical properties of the medium, a technique known as passive microrheology. This technique has been applied to investigate the motion of lipids and proteins within membranes, molecules in the nucleus organelles and molecules therein, lipid granules, vesicles, and particles introduced in the cytoplasm or the nucleus. Additionally, single-particle tracking has been extensively used in the study of reconstituted lipid bilayers, intermittent diffusion between 3D and either 2D (e.g., a membrane) or 1D (e.g., a DNA polymer) phases, and synthetic entangled actin networks.

Methods

The most common type of particles used in single particle tracking are based either on scatterers, such as polystyrene beads or gold nanoparticles that can be tracked using bright field illumination, or fluorescent particles. For fluorescent tags, there are many different options with their own advantages and disadvantages, including quantum dots, fluorescent proteins, organic fluorophores, and cyanine dyes.

On a fundamental level, once the images are obtained, single-particle tracking is a two step process. First the particles are detected and then the localized different particles are connected in order to obtain individual trajectories.

Besides performing particle tracking in 2D, there are several imaging modalities for 3D particle tracking, including multifocal plane microscopy, double helix point spread function microscopy, and introducing astigmatism via a cylindrical lens or adaptive optics.

Brownian diffusion

Main article: Brownian motion

References

References

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  2. (2015-10-29). "A review of progress in single particle tracking: from methods to biophysical insights". Reports on Progress in Physics.
  3. (2006). "Methods to Track Single-Molecule Trajectories". Langmuir.
  4. (2013-03-12). "Anomalous transport in the crowded world of biological cells". Reports on Progress in Physics.
  5. (5 November 2021). "In-vivo Single-Molecule Imaging in Yeast: Applications and Challenges". Journal of Molecular Biology.
  6. (2012). "Strange kinetics of single molecules in living cells". Physics Today.
  7. (2018). "Single Molecule Imaging in Live Embryos Using Lattice Light-Sheet Microscopy". Springer.
  8. (December 2016). "Single molecule tracking of Ace1p in Saccharomyces cerevisiae defines a characteristic residence time for non-specific interactions of transcription factors with chromatin". Nucleic Acids Research.
  9. (2018-12-06). "Single-Molecule Analysis Reveals Linked Cycles of RSC Chromatin Remodeling and Ace1p Transcription Factor Binding in Yeast". Molecular Cell.
  10. (2014-07-18). "Single-molecule analysis of transcription factor binding at transcription sites in live cells". Nature Communications.
  11. (2017-07-01). "Quantifying transcription factor binding dynamics at the single-molecule level in live cells". Methods.
  12. (June 2018). "tRNA tracking for direct measurements of protein synthesis kinetics in live cells". Nature Chemical Biology.
  13. (2020-10-12). "Direct measurements of mRNA translation kinetics in living cells". Nature Communications.
  14. Wirtz, Denis. (2009). "Particle-Tracking Microrheology of Living Cells: Principles and Applications". Annual Review of Biophysics.
  15. (1997). "Single-Particle Tracking: Applications to Membrane Dynamics". Annual Review of Biophysics and Biomolecular Structure.
  16. Krapf, Diego. (2015). "Lipid Domains". Elsevier.
  17. Golding, Ido. (2006). "Physical Nature of Bacterial Cytoplasm". Physical Review Letters.
  18. (2016-10-28). "Increased spatiotemporal resolution reveals highly dynamic dense tubular matrices in the peripheral ER". Science.
  19. Tolić-Nørrelykke, Iva Marija. (2004). "Anomalous Diffusion in Living Yeast Cells". Physical Review Letters.
  20. Jeon, Jae-Hyung. (2011). "In Vivo Anomalous Diffusion and Weak Ergodicity Breaking of Lipid Granules". Physical Review Letters.
  21. (2018). "Mitochondrial dynamics tracking with iridium(III) complexes". Current Opinion in Chemical Biology.
  22. (2009). "Single-Molecule Fluorescence Studies of a PH Domain: New Insights into the Membrane Docking Reaction". Biophysical Journal.
  23. (2015-12-07). "Superdiffusive motion of membrane-targeting C2 domains". Scientific Reports.
  24. Wong, I. Y.. (2004). "Anomalous Diffusion Probes Microstructure Dynamics of Entangled F-Actin Networks". Physical Review Letters.
  25. (2009-09-08). "Anomalous yet Brownian". Proceedings of the National Academy of Sciences.
  26. (2008). "High accuracy 3D quantum dotifocal plane microscopy for the study of fast intracellular dynamics in live cells". [[Biophysical Journal]].
  27. (2010). "Three-dimensional localization precision of the double-helix point spread function versus astigmatism and biplane". [[Applied Physics Letters]].

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laboratory-techniques