Size Sorting of Exosomes by Tuning the Thicknesses of the Electric Double Layers on a Micro-Nanofluidic Device

Exosomes, a type of extracellular vesicle with a diameter of 30-150 nm, perform key biological functions such as intercellular communication. Recently, size sorting of exosomes has received increasing attention in order to clarify the correlation between their size and components. However, such sorting remains extremely difficult. Here, we propose to sort their size by controlling their electrokinetic migration in nanochannels in a micro-nanofluidic device, which is achieved by tuning the thickness of the electric double layers in the nanochannels. This approach was demonstrated experimentally for exosomes smaller than 250 nm. Using different running buffer concentrations (1 × 10^-3, 1 × 10^-4, and 1 × 10^-5 M), most of the exosomes larger than 140, 110, and 80 nm were successfully cut off at the downstream of the nanochannels, respectively. Therefore, it is clarified that the proposed method is applicable for the size sorting of exosomes.