Molecular Dynamics Simulations Of Colloids In Single Solid-State Nanopores

The transport of biomolecules and small particles such as viruses through constrained geometries is critical to understand for efficient molecular separations, detection and selective binding for biomedical and biodefense applications. To develop improved capabilities for isolating and controlling both particles and molecules, there is a need for models developed by computational techniques and matched by well-integrated experiments. Here, we use molecular dynamics simulations to study the flow of colloidal silica particles (diameter ∼50-100 nm) through cylindrical nanopores with diameter 200nm, and lengths 50-100 nm. Particle translocation is investigated in the presence of an applied electric field. We demonstrate the molecular origin of the pore resistance change that occurs once the colloid is inside the pore. The rate at which particles transit the nanopore is highly dependent on the dispersion forces and the electric field, which is in turn a function of both the applied voltage and the pore geometry. Models are supported by experimental findings obtained with resistive pulse sensing. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, LLNL-ABS-644260.