Restricted and Unrestricted Migration Mechanisms of Silica Nanoparticles in Agarose Gels and Their Utilization for the Separation of Binary Mixtures

Abstract

The migration of SiO2 nanoparticles (NP) was investigated during agarose gel electrophoresis with various gel mesh sizes. As a model system, spherical SiO2 NP of different sizes were synthesized by Stober synthesis, and surface-modified by covalently binding different types of ligands to tailor the zeta potential as required. In the following step, agarose gels were cast with TBE (Tris/Borate/EDTA) buffer solution, thereby controlling the mesh sizes by varying agarose concentration, with higher concentrations leading to smaller mesh sizes. Additionally, the applied voltage could be varied for different electrophoretic experiments. Generally, small mesh sizes and high applied voltages lead to faster particle migration. The migration of SiO2 NP occurs under two regimes: restricted migration, where small mesh size interferes with large particles so that the gel is acting similar to a sieve; and unrestricted migration, where mesh size does not influence the particles’ migration behavior and they move accordin...