Droplet-Based Microfluidics for High-Throughput Studies of Enzyme Catalyzed Reactions

Microfluidics involves the manipulation and interrogation of miniscule amounts of fluid within hand-sized devices. Water-in-oil emulsions were flowed through microfluidic channels to generate steady streams of aqueous droplets. The novelty of our newly developed microfluidic system is that, in a short period of time and with small volumes, it can generate thousands of nanoliter size emulsion droplets where each drop has an incrementally different concentration of aqueous solution.  This is achieved by flowing the outlet of a small aqueous-solution mixing tank into the droplet generating microfluidic channel.  The outlet concentration of the mixing tank can then be controlled by the residence time and solution concentration.  We have demonstrated that we can generate an array of droplets with a concentration gradient of a fluorescent dye.  Our aim for this proposed research project are to make an array of droplets where each has a slightly different, but controlled, concentration of substrate.  Having such a complete set of nano-sized “test tubes” will allow us to collect a large data set of enzyme-catalyzed reaction kinetics in a single experimental run, and thus reduce the time and amounts of fluid.  The ultimate goal is to be able to provide a microfluidic platform that can be used to perform high-throughput studies of important biochemical reactions.