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Single-Molecule Tracking Microscopy - A Tool for Determining the Diffusive States of Cytosolic Molecules
Published on: September 5, 2019
Thermodynamics of gradient driven transport: application to single-particle tracking
1Department of Physics, University of Maine, Orono, Maine 04469, USA. astumian@maine.edu
The Journal of Physical Chemistry. B
|July 30, 2009
Summary
Single-particle tracking can map free-energy landscapes by analyzing forward and backward trajectory probabilities. This method works even with external gradients, revealing particle transport dynamics without assuming thermodynamic equilibrium.
Area of Science:
- Physics
- Physical Chemistry
- Statistical Mechanics
Background:
- Single-particle tracking (SPT) enables the observation of individual particle or molecule trajectories.
- Understanding particle transport in complex systems is crucial in various scientific fields.
Purpose of the Study:
- To demonstrate that SPT can be used to determine the free-energy landscape of particle transport.
- To validate a theoretical equality relating trajectory probabilities to free energy differences.
Main Methods:
- Utilizing single-particle tracking techniques to measure particle trajectories.
- Analyzing the ratio of forward and backward trajectory probabilities between two points.
- Applying a derived theoretical equality to experimental data.
Main Results:
- The ratio of forward to backward trajectory probabilities is directly related to the free energy difference between the start and end points.
- This relationship holds true even in the presence of external gradients (pressure, temperature, electric field).
- The derived equality is P(x(a) --> x(b), Deltat) = P(x(b) --> x(a), Deltat) exp(-DeltaG/k(B)T).
Conclusions:
- SPT experiments can successfully map free-energy landscapes for particle transport.
- This mapping is achievable irrespective of whether the system is in thermodynamic equilibrium.
- The findings provide a powerful experimental tool for studying complex transport phenomena.
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