Manipulating samples as droplets within microfluidic devices has emerged as an interesting approach for chemical analysis and screening. In segmented flow, one embodiment of this technology, nanoliter samples are manipulated in microfluidic channels as plugs separated by an immiscible fluid, such as air or fluorinated oil. These plugs serve as miniature test-tubes in which reactions can be performed at high throughput. Microfluidic tools have been developed to split, dilute, extract, and filter such plugs at rates >10 samples/s. We have developed methods to analyze plug content by electrophoresis and mass spectrometry (MS). A natural application of this technology is for high throughput screening. By coupling droplet manipulation with MS detection, it is possible to greatly reduce reagent consumption and eliminate the need for fluorescent labels or coupled reactions. The technology and application to screens of deacetylase reactions and protein-protein interactions will be presented. A more involved screening allows for monitoring reactions of enzyme variants to identify new biocatalysts. Droplet technology can also be used for chemical monitoring or sensing applications. In this approach samples emerging from a miniaturized sampling device are segmented for later analysis. We have used this method to monitor neurotransmitter dynamics in the brain. The technology and application to studies of neurotransmission in a Huntington’s disease models will be demonstrated.
Robert Kennedy developed an interest in analytical chemistry and chemical separations while earning his BS degree in chemistry at the University of Florida. He became fascinated with the ability of GC to separate subtly different molecules while he was performing undergraduate research in organic chemistry. His analytical classes taught by Prof. John Dorsey further enhanced this interest. He went on to earn a PhD with James Jorgenson at University of North Carolina where is work focused on using open tubular LC to analyze single cells. After a post-doc with Mark Wightman he started his own research program at University of Florida before moving to University of Michigan as the Hobart H. Willard Professor of Chemistry in 2002. His research has combined his lifelong interest in biology with chemical analysis and separations. A theme of his group has been development of miniaturized, high-speed separations for sensing, detection of non-covalent complexes, and screening. His group has developed capillary separation methods for monitoring neurotransmitters in vivo. These methods have been used for studying changes in neurotransmitter concentrations associated with behavior and diseases. His group has also developed microfluidic electrophoresis devices for monitoring insulin secretion from pancreatic β-cells. These methods are coupled with LC-MS metabolomics to understand the biochemical mechanism of insulin secretion and perturbations associated with diabetes. His group is also researching use of rapid electrophoretic and mass spectrometric assays for high-throughput screening. His work has been recognized by several awards including ACS Award in Chromatography, McKnight Award for Technical Innovations in Neuroscience, EAS Separation Science Award, Golay Award for Achievements in Chromatography, The Ralph Adams Award in Bioanalytical Chemistry and several teaching awards. He has held several service posts and is presently Associate Editor of Analytical Chemistry and Chair of the Chemistry Department at University of Michigan.
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WTHR 320, Purdue University, West Lafayette, IN