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From Fast Fluorescence Imaging to Molecular Diffusion Law on Live Cell Membranes in a Commercial Microscope
Published on: October 9, 2014
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Stochastic Pairwise Forces Enhance Tracer Diffusion in Nonmotile Active Matter.
Henry Alston1,2, Raphaël Voituriez3,4, Thibault Bertrand1
1Imperial College London, Department of Mathematics, South Kensington, London SW7 2AZ, United Kingdom.
Physical Review Letters
|April 11, 2026
Summary
Randomly fluctuating interactions in biological systems can enhance particle diffusion. This study reveals how reciprocal stochastic forces create active suspensions, boosting tracer particle movement without self-propulsion.
Area of Science:
- Physics
- Biophysics
- Statistical Mechanics
Background:
- Stochasticity is inherent in biological interactions, but its large-scale effects are unclear.
- Understanding random forces in biological systems is crucial for molecular motors and cell adhesion.
Purpose of the Study:
- To investigate how reciprocal stochastic interactions influence the dynamics of active suspensions.
- To determine if random fluctuations can enhance the diffusion of external particles.
Main Methods:
- Developed a lattice model with pairwise dynamics that minimally break detailed balance.
- Derived a coarse-grained dynamical theory for spatiotemporal density fluctuations.
- Computed the self-diffusion coefficient of a tracer particle in the active fluid.
Main Results:
- Reciprocal, fluctuating interactions create active suspensions.
- These suspensions enhance the diffusion of an external tracer particle.
- An elevated effective temperature was observed at short wavelengths.
Conclusions:
- Purely reciprocal stochastic interactions offer a novel mechanism for enhanced diffusivity.
- This provides a generic route to enhanced diffusion in dense, nonequilibrium suspensions.
- Highlights the significant impact of stochasticity on biological system dynamics.
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