Elucidating the origin of anomalous diffusion in crowded fluids

Area of Science:

• Biophysics
• Physical Chemistry
• Cell Biology

Background:

• Anomalous diffusion is common in crowded biological environments like cytoplasm.
• The specific stochastic process governing this subdiffusion remains largely unknown.

Purpose of the Study:

• To identify the underlying stochastic process responsible for crowding-induced subdiffusion in biological fluids.
• To differentiate between potential models like fractional Brownian motion and continuous time random walks.

Main Methods:

• Utilized fluorescence correlation spectroscopy (FCS) for experimental measurements.
• Performed computational simulations to model diffusion processes.

Main Results:

• Experimental data and simulations align with fractional Brownian motion or obstructed diffusion models.
• These models feature stationary increments, consistent with observations.
• Continuous time random walk models, with non-Gaussian propagators, were inconsistent with the findings.

Conclusions:

• Crowding-induced subdiffusion in biological fluids is best described by models with stationary increments.
• Fractional Brownian motion or obstructed diffusion are likely mechanisms, excluding continuous time random walks.