Non-Fickian single-file pore transport

Area of Science:

• Physics
• Statistical Mechanics
• Soft Matter Physics

Background:

• Single-file diffusion describes particle movement in confined spaces.
• Particle immobilization via binding/unbinding can significantly slow collective transport.
• Understanding transport in short, one-dimensional channels is crucial for nanoscale systems.

Purpose of the Study:

• To investigate anomalous transport in short, pore-like channels.
• To explore the emergence of non-Fickian diffusion regimes.
• To characterize the influence of binding and unbinding kinetics on particle flux.

Main Methods:

• Utilized a symmetric exclusion process with fully stochastic dynamics.
• Simulated particle diffusion in short, one-dimensional channels.
• Analyzed the average particle flux (〈Φ〉) as a function of channel length (L).

Main Results:

• A non-Fickian regime was observed for shorter channels with slow binding kinetics.
• The average flux exhibits a scaling of 〈Φ〉∼1/L³ in this regime.
• A two-state model accurately describes the behavior, with switching between high-flux and low-flux states.

Conclusions:

• Slow binding kinetics in short channels lead to anomalously slow, non-Fickian transport.
• The system transitions between directed transport bursts and leaky states.
• Channel length and binding rates are critical determinants of transport efficiency.