# Analytical Model for Particle Capture in Nanopores Elucidates Competition among Electrophoresis, Electroosmosis, and Dielectrophoresis

## TL;DR

This paper develops a theoretical model to explain how nanoparticles are captured by nanopores, considering various electrical and fluid forces.

## Contribution

The novel contribution is an analytical model that explains nanoparticle capture by nanopores, incorporating electrophoresis, electroosmosis, and dielectrophoresis.

## Key findings

- The model splits capture time into approaching and entrance phases.
- Dielectrophoresis can induce capture for both positive and negative voltages.
- Experiments with α-hemolysin and β-hairpin peptides confirmed the model's predictions.

## Abstract

The
interaction between nanoparticles dispersed in a fluid and
nanopores is governed by the interplay of hydrodynamical, electrical,
and chemical effects. We developed a theory for particle capture in
nanopores and derived analytical expressions for the capture rate
under the concurrent action of electrical forces, fluid advection,
and Brownian motion. Our approach naturally splits the average capture
time in two terms, an approaching time due to the
migration of particles from the bulk to the pore mouth and an entrance time associated with a free-energy barrier at the
pore entrance. Within this theoretical framework, we described the
standard experimental condition where a particle concentration is
driven into the pore by an applied voltage, with specific focus on
different capture mechanisms: under pure electrophoretic force, in
the presence of a competition between electrophoresis and electroosmosis,
and finally under dielectrophoretic reorientation of dipolar particles.
Our theory predicts that dielectrophoresis is able to induce capture
for both positive and negative voltages. We performed a dedicated
experiment involving a biological nanopore (α-hemolysin) and
a rigid dipolar dumbbell (realized with a β-hairpin peptide)
that confirms the theoretically proposed capture mechanism.