Size Based Nanoparticle Separation Using Dielectrophoretic Focusing for Femtosecond Nanocrystallography of Membrane Proteins.

We propose a method to separate photosystem I crystals based on size using a combination of dielectrophoresis (DEP) and electrokinesis (EK) within a microfluidic device. In this work, a model system utilizing polystyrene beads of two sizes is employed to observe the effects of DEP and EK on particles as they pass through a microsorter via electroosmosis. Particle counting and fluorescence intensity measurements are used for quantitative analysis of experimental data. For comparison, numerical simulations were performed for further confirmation that the proposed device is capable of sorting particles based on their size. Our experimental and theoretical results are in agreement and show a high degree of sorting efficiency between both particle types making this a promising solution for protein crystal sorting.