Hobart H Willard Distinguished University Professor of Chemistry, Pharmacology
About
Our primary goal is to develop nanoscale analytical techniques and explore their use in the measurement of neurotransmitters and hormones both in vivo and at single cells. This goal requires development of techniques capable of measuring zeptomole (10-21 mole) quantities in chemically complex nanoliter samples.
For in vivo measurements, we are coupling capillary zone electrophoresis (CZE) and capillary liquid chromatography (LC) with in vivo sampling methods. The sampling probes continuously remove samples which are periodically and automatically injected into the separation column. In one project, we have developed a 1 s CZE separation of several neurotransmitters which allows high resolution monitoring of neurotransmitter activity. Another project, just underway, involves combining capillary LC with mass spectrometry to discover novel neurotransmitters.
In the area of single cell analysis, we have focused on development of microsensors and confocal fluorescence microscopy for measurement of insulin secreted from cells with millisecond resolution. We are also pursuing analytical methods that allow simultaneous detection of intracellular messengers such as Zn2+, Ca2+, oxygen, and glucose at the same cells. The combination of these methods will provide a complete chemical picture of the cell as it functions.
As we begin to understand the dynamics of extracellular signaling molecules, it also becomes important to understand the intracellular chemical changes that result from the interaction of such molecules with receptors. To facilitate these studies, we are developing techniques based on capillary electrophoresis, fluorescence detection, and mass spectrometry to detect and model intracellular signal transduction. Applications include detection of G-proteins, proteins with SH2 domains, and phosphorylated proteins. Such measurements can be considered directed proteomics measurements.
All of these techniques involve development of novel analytical chemistry as well as instrumentation. Recently, a significant effort has been made in developing microfabricated instruments for micro-total analytical systems (mu TAS) to perform the analyses described above. In addition to the fundamental analytical work, application of these methods to studies of brain and endocrine function as well as diseases such as diabetes and Alzheimer's are underway in various collaborations.
Representative Publications
1) Song P, Mabrouk OS, Hershey ND, & Kennedy RT. (2012) “In vivo neurochemical monitoring using benzoyl chloride derivatization and liquid chromatography mass spectrometry” Analytical Chemistry, 84:412-419.
2) Kennedy RT. (2013) “Emerging trends in in vivo neurochemical monitoring by microdialysis.” Current Opinion in Chemical Biology 17:860-867.
3) Dugan CE, Cawthorn WP, MacDougald OA, Kennedy RT (2014) “Multiplexed microfluidic enzyme assays for simultaneous detection of lipolysis products from adipocytes” Analytical and Bioanalytical Chemistry 406:4581-4589.
4) Flak JN, Patterson CM, Garfield AS, D'Agostino G, Goforth PB, Sutton AK, Malec PA, Wong JM, Germani M, Jones JC, Rajala M, Satin L, Rhodes CJ, Olson DP, Kennedy RT, Heisler LK, Myers MG Jr. (2014) “Leptin-inhibited PBN neurons enhance responses to hypoglycemia in negative energy balance” Nature Neuroscience 17(12):1744-50.
5) Guetschow ED, Steyer DJ, Kennedy RT. (2014) “Subsecond electrophoretic separations from droplet samples for screening of enzyme modulators” Analytical Chemistry 86:10373-9.
6) Sun S, Kennedy RT. (2014) “Droplet electrospray ionization mass spectrometry for high throughput screening for enzyme inhibitors” Analytical Chemistry 86:9309-14.
7) ElAzzouny MA, Evans CR, Burant CF, Kennedy RT. (2015) “Metabolomics Analysis Reveals that AICAR Affects Glycerolipid, Ceramide and Nucleotide Synthesis Pathways in INS-1 Cells” PLoS One 10:e0129029.
8) Guetschow ED, Kumar S, Lombard DB, Kennedy RT. (2016) “Identification of sirtuin 5 inhibitors by ultrafast microchip electrophoresis using nanoliter volume samples” Analytical & Bioanalytical Chemistry 408(3):721-31.
9) Hamid AA, Pettibone JR, Mabrouk OS, Hetrick VL, Schmidt R, Vander Weele CM, Kennedy RT, Aragona BJ, Berke JD. (2016) “Mesolimbic dopamine signals the value of work” Nature Neuroscience 19:117-26.
10) Lee WH, Ngernsutivorakul T, Mabrouk OS, Wong JM, Dugan CE, Pappas SS, Yoon HJ, Kennedy RT. (2016) “Microfabrication and in Vivo Performance of a Microdialysis Probe with Embedded Membrane” Analytical Chemistry 88(2):1230-7.
11) Malec P, Wong JM, Mabrouk OS, Dus M, Kennedy RT (2016) “Benzoyl Chloride Derivatization with Liquid Chromatography-Mass Spectrometry for Targeted Metabolomics of Neurochemicals in Biological Samples” Journal of Chromatography A, 1446:78-90.
12) Jin S, Furtaw M, Chen H, Lamb D, Ferguson S, Cleveland N, Dawod M, Kennedy R (2016) “Multiplexed Western Blotting Using Microchip Electrophoresis”, Analytical Chemistry, 88:6703-10.
13) Sun S, Buer BC, Marsh EN, Kennedy RT (2016) “A Label-free Sirtuin 1 Assay based on Droplet-Electrospray Ionization Mass Spectrometry” Analytical Methods, 8:3458-3465.
14) Ouimet CM, Shao H, Rauch JN, Dawod M, Nordhues B, Dickey CA, Gestwicki JE, Kennedy RT. (2016) “Protein Cross-Linking Capillary Electrophoresis for Protein-Protein Interaction Analysis.” Analytical Chemistry, 88: 8272-8.
15) Grinias JP, Kennedy RT. (2016) “Advances in and prospects of microchip liquid chromatography” Trends in Analytical Chemistry, 81:110-117.perfusion sampling in vivo with on-line analysis of amino acids . "
Research Areas(s)
- Analytical Chemistry
Bioanalytical Chemistry
Bioinorganic Chemistry
Chemical Biology
Optics and Imaging
Sensor Science
Nanoscale analytical techniques
Chemical separations
Mass spectrometry
Microfluidics
Neurochemistry
Islet Biology
Award(s)
- Eastern Analytical Symposium Award for Outstanding Achievements in Separations, 2012
- Marcel Golay Award, 2012
- NIBB Merit Award, 2008
- NIDDK Merit Award, 2006
- ACS Findeis Award
- Benedetti-Pichler Award for Microchemical Chemistry
Fellowships
- American Association for the Advancement of Science Fellow, 2008
- Alfred P. Sloan Fellowship
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Other Positions
- Beckman Foundation Young Investigator
- NSF National Young Investigator
