ORGN 442

This presentation describes a microfluidic chip for performing kinetic measurements with millisecond resolution.  Each kinetic profile can be obtained using less than 100 nL of solutions of reagents because this system relies on chaotic advection inside moving droplets rather than turbulence, to achieve rapid mixing. (This method of mixing is described in H. Song, et. al. Angew. Chem. Int. Ed. 2002, 42, 768-772.)  Fabrication of these devices in PDMS is straightforward and no specialized equipment except for a standard microscope with a CCD camera is needed to run the experiments.  Each fluorescence image was acquired for 2 s, and required less than 70 nL of the reagent solutions.  By using on-chip reagent dilution, single-turnover kinetics of ribonuclease A was measured.  This system could serve as an inexpensive and economical complement to stopped-flow methods for a broad range of time-resolved experiments in chemistry and biochemistry.