LAUSR

Abstract We present a novel continuous two-dimensional asymmetrical flow field-flow fractionation (2D-AF4) system that is able to fractionate a feed solution of nano-sized solutes (e.g., proteins, nanoparticles) according to their size in aqueous solvents. The key component that generates the continuous separation is a microstructured ultrafiltration membrane with slanted grooves on its surface. The solutes are migrating over the grooves, which are causing a lateral displacement from the direction of the main channel flow, and they are exiting the channel at different outlets. The deflection angle depends on the mean layer thickness of the solutes and consequently on their hydrodynamic radius; with a specific cross-flow, larger solutes exhibit a larger deflection angle which results in a spatial separation. By adjusting the outlet flow and the cross-flow rate, the system can be optimized with respect to purity, recovery and speed. A prototype device has been designed and tested. A proof of principle of the continuous fractionation is demonstrated with mixtures of two model proteins, apoferritin (443 kDa) and thyroglobulin (669 kDa), and of two polystyrene latex standards with diameters of 34 and 102 nm.