Refolding of Beta-Galactosidase In a Microfluidic Device

We have developed a microfluidic device that has the unique capability of automating the combinatorial process of finding solution conditions for protein refolding. The microfluidic approach offers the potential advantages of automation, cost-effectiveness, compatibility with optical detection, and a million-fold reduction in sample volumes as opposed to conventional techniques of hand-pipetting or using robotic systems. The device is a multi-layered Polydimethylsiloxane (PDMS) on glass device with automated controls for reagent aliquoting and mixing. Refolding experiments have been performed on the protein β-galactosidase, which is an essential enzyme in the human body that catalyzes the hydrolysis of β-galactosides like lactose into monosaccharides. The refolding yield has been quantified on-chip using fluorescein di-β-D-galactopyranoside (FDG), a caged-fluorescent molecule. The refolding protocol and the fluorometric assay are optimized for best on-chip signal intensity. The main impact of this work is on greatly reducing the cost of realizing protein pharmaceuticals.