Microfluidic dialysis cell for characterization of macromolecule interactions

Abstract

Microfluidic dialysis is a promising tool for characterisation of macromolecule interactions and responsive materials, but until now it has been limited to the characterisation of high molecular weight molecules. Here, we introduce a low molecular weight cut-off dialysis membrane fabricated by coating a rigid membrane filter with a layer of crosslinked hydrogel. The modified hybrid silicone/glass microfluidic cells retain low molecular weight samples at a well-defined concentration for long periods of time, while allowing timely changes to be made in the fluid's supporting solvent (i.e. pH, ionic strength, ionic species). Straightforward access to the sample using high-resolution optical microscopy enables in situ characterisation of the sample's physical properties in response to changes in solvent conditions. A proof of principle measurement investigating the pH-sensitive binding between the protein/polysaccharide pair, neurocan and hyaluronan, is presented to demonstrate the integration of protein retention, solvent switching and fluorescence recovery after photobleaching (FRAP).