Microfluidic Free-Flow Paper Electrochromatography for Continuous Separation of Glycans

Microfluidic free-flow electrophoresis (mu-FFE) is widely used for continuous separation of charged analytes. However, mu-FFE is limited in the separation of analytes with the same electrophoretic mobility. In this work, we developed a novel microfluidic free-flow paper electrochromatography (mu-FFPE) by combining mu-FFE with filter paper-based chromatography, enabling continuous separation of analytes through the mechanism of both mu-FFE and paper chromatography. Numerical simulation was applied to demonstrate the advantages of adding filter paper as the stationary phase of mu-FFE. With the filter paper, a more stable separation system was achieved. The device was applied to the separation of simple mixtures of dyes and complex mixtures of glycans. With the mu-FFPE fractionation, much more glycans and glycan types can be identified by LC-MS, demonstrating the value of the method in biological analysis. The mu-FFPE can provide a new platform for the separation and analysis of various biological molecules.