Dr. Dimitri Pappas
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Title: |
Associate Professor |
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Education: |
Ph.D., University of Florida, 2002; Postdoctoral Study, University of Florida, 2002 |
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Research Area: |
Analytical Chemistry |
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Office: |
Chemistry 300-B |
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Pappas Receives Chancellor's Council Research Award
Pappas is an associate professor in the Department of Chemistry & Biochemistry at
Texas Tech. Previously serving as a senior scientist at Johnson Space Center, Pappas
has earned national and international recognition for his work using new chemical
methods to study and detect illnesses such as heart disease and cancer, and has been
noted as one of the top bioanalytical chemists in the nation.
Photos
Principal Research Interests
- Bioanalytical Chemistry
- Cellular Analysis
- Microfluidics
The Pappas group uses several analytical techniques to study mechanisms of tissue loss and regeneration. The main mechanism of tissue loss under investigation is apoptosis (programmed cell death). Apoptosis plays a critical role in the selective removal of cells through either a receptor-mediated or intrinsic pathway. Several methods developed in the Pappas labs have helped to elucidate the mechanisms and temporal dynamics of apoptosis.
Differential Mobility Cytometry, a new method developed by Dr. Pappas and his students, is capable of monitoring cell adhesion, separating cells, and label-free detection. This approach features long observation times, temporal resolution on the time scale of seconds or less, and the ability to maintain cells in homeostasis during separation. Dr. Pappas has demonstrated the technique for cell separation, adhesion studies, apoptosis induction/detection, and cell loss. Differential mobility has been used with traditional protein-based ligands or, more recently, with aptamers as the capture molecule in both capillary and microfluidic formats.
Single Molecule and Fluorescence Correlation Spectroscopy (FCS) techniques have also been used in the Pappas group to study cell growth and death. Using FCS and fluorogenic probes, his students have been able to detect caspase activity in an apoptotic cell in less than one hour after induction--the fastest measurement of such activity in a living cell. FCS has also been used to investigate the temporal dynamics of protease activity in cells, as well as flow effects in some microfluidic designs developed by Pappas group students. A subset of these single molecule projects investigates the light harvesting and energy transfer properties of phycobiliproteins for use as fluorescent labels and/or light gathering materials (Funded by the Robert A. Welch Foundation).
Representative Publications
- "Differential Mobility Cytometry." K. Wang, X. Solis-Wever, C. Aguas, Y. Liu, P. Li, D. Pappas Analytical Chemistry,2009, 81, 3334-3343.
- "Cell Culture Chip with Low-Shear Mass Transport," K. Liu, D. Dang, T. Harrington, K. Bayer, D. Pappas, Langmuir,2008, 24, 5955-5960.
- "Measuring Complexation by Single Molecule Fluorescence Anisotropy." S.M. Burrows, D. Pappas, The Analyst,2008, 133, 870-873.
- "Isolation and Counting of Multiple Cell Types Using an Affinity Separation Device," K. Wang, B. Cometti, D. Pappas, Analytica Chimica Acta,2007, 601, 1-9.
- "Cellular Separations: A Review of New Challenges in Analytical Chemistry," D. Pappas, K. Wang, Analytica Chimica Acta,2007,601, 26-35.
- "Open-Tubular Capillary Cell Affinity Chromatography: Single and Tandem Blood Cell Separation," K. Wang, M.K. Marshall, G. Garza, D. Pappas, Analytical Chemistry,2008,80, 2118-2124.
- "Exploring Biomolecular Interactions by Single Molecule Fluorescence," D. Pappas, S.M. Burrows, R.D. Reif, TrAC: Trends in Analytical Chemistry,2007, 26, 884-894.
- "Investigation of Photobleaching and Saturation of Single Molecules by Fluorophore Recrossing Events," S. Burrows, R.D. Reif, D. Pappas, Analytical Chimica Acta,2007, 589, 135-142.