Driven diffusion against electrostatic or effective energy barrier across α-hemolysin.

Area of Science:

• Biophysics
• Computational Biology
• Physical Chemistry

Background:

• The alpha-hemolysin (αHL) pore is a channel protein relevant for biological transport phenomena.
• Understanding charged particle translocation through nanopores is crucial for biosensing and drug delivery applications.

Purpose of the Study:

• To analyze the translocation dynamics of a charged particle through an αHL pore.
• To develop and validate a theoretical model for driven diffusion over an energy barrier.

Main Methods:

• Solving Poisson's equation to obtain a 1D electrostatic potential.
• Employing Brownian dynamics simulations for particle transport analysis.
• Deriving analytical expressions for translocation time statistics.

Main Results:

• An analytical expression for the average translocation time was derived and validated against simulations.
• Translocation time distributions were accurately described by a simplified square barrier model.
• The model demonstrated accuracy even in low-applied voltage regimes where traditional approximations fail.

Conclusions:

• The developed driven diffusion model provides an accurate framework for understanding particle translocation through nanopores.
• The simplified square barrier approach offers a robust alternative to complex potential models.
• The empirical Laplace transform technique simplifies the comparison between theoretical predictions and simulation data.