MEASUREMENT OF FAST ENZYME KINETICS VIA DROPLET MERGING

THE USE OF HIGH SPEED (1-10M/S) 25-200FM DIAMETER DROPLETS MERGING IN FLIGHT WILL BE USED TO MEASURE ENZYME KINETICS IN THE 50FS-1MS RANGE. TWO EXTREMELY REPEATABLE DROPLET STREAMS ARE PRODUCED USING TECHNIQUES DEVELOPED FOR INK-JET PRINTING SYSTEMS. THE TWO DROPLET STREAMS MERGE AND A REACTION WILL TAKE PLACE ALMOST INSTANTANEOUSLY. THE ENZYME REACTION CAUSES CHANGES IN ABSORPTION, FLUORESCENCE, OR CHEMILUMINESCENCE, DEPENDING ON THE ENZYME AND SUBSTRATE USED IN THE REACTION. IN PHASE I OF THIS STUDY, CHEMILUMINESCENT REACTIONS WILL BE EVALUATED. THE PHOTONS EMITTED ARE DETECTED BY A PHOTOMULTIPLIER TUBE FOCUSED ON A REGION OF THE MERGED DROPLET STREAM. THE REGION CORRESPONDS TO THE LENGTH A DROPLET WOULD TRAVEL IN 1MS. THE DETECTOR IS GATED TO MEASURE EMISSIONS FOR @FS-1MS. (WITH 1FS RESOLUTION) AND THE GATE IS SYNCHRONIZED WITH THE DROPLET CREATION FREQUENCY, ALLOWING THE EMISSIONS FROM THOUSANDS OF DROPS TO BE INTEGRATED. THE SMALL DIAMETER OF THE DROPLETS INSURES RAPID MIXING. THE REPEATABILITY OF DROPLET FORMATION INHERENT WITH INK-JET TECHNOLOGY ALLOWS PHOTONS TO BE GATHERED OVER LONG TIME PERIODS, THUS INCREASING THE SENSITIVITY OF THE MEASUREMENT.