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Strange kinetics of bulk-mediated diffusion on lipid bilayers
Diego Krapf1, Grace Campagnola, Kanti Nepal
1Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO 80523, USA. krapf@engr.colostate.edu.
Physical Chemistry Chemical Physics : PCCP
|April 21, 2016
Summary
Bulk-mediated diffusion, where molecules briefly leave surfaces, exhibits infinite mean jump length. This study reveals strong anomalous diffusion on lipid bilayers, challenging standard diffusion models.
Area of Science:
- Physical Chemistry
- Biophysics
- Surface Science
Background:
- Diffusion at solid-liquid interfaces is vital for many processes.
- Bulk-mediated diffusion involves transient molecular release into the liquid.
- This phenomenon can lead to infinite mean jump lengths and weak ergodicity breaking.
Purpose of the Study:
- To investigate the statistical properties of bulk-mediated diffusion.
- To analyze diffusion on a supported lipid bilayer using single-particle tracking.
- To characterize deviations from standard diffusion behavior.
Main Methods:
- Single-particle tracking experiments.
- Analysis of time-averaged mean square displacement (MSD).
- Investigation of displacement statistics and fractional moments.
Main Results:
- Time-averaged MSD of individual trajectories did not converge to the ensemble MSD.
- The distribution of time-averaged MSD agreed with a Lévy flight model.
- Strong anomalous diffusion was observed, with time-dependent MSD and non-linear scaling exponents.
Conclusions:
- Bulk-mediated diffusion on lipid bilayers exhibits strong anomalous behavior.
- Standard diffusion theories and the central limit theorem break down.
- Experimental observations align with Lévy flight models, highlighting complex surface diffusion dynamics.
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