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

Patrizio Ansalone1, Mauro Chinappi2, Lamberto Rondoni3

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We analyzed charged particle translocation through an alpha-hemolysin (αHL) pore, developing a theory for translocation time that accurately models driven diffusion over energy barriers, even at low voltages.

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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.