个人简介

Ph.D., University of Florida, 2002; Postdoctoral Study, University of Florida, 2002 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.

研究领域

Analytical Chemistry

Our research focuses on bioanalytical methodologies to solve medical problems. My research group vertically integrates our efforts to solve these problems—developing new, disruptive technologies. Our work is translational in nature, as we span multiple disciplines to elucidate complex biological problems. The overall theme of our work is the integration of microfluidic and spectroscopic approaches to investigate the areas of heart disease, blood analysis, cancer, and several other biomedical issues. Our work involves collaborators in the medical community and within our own department as well. One of the key areas of our research involves the role of oxygen and hypoxia in cell survival. We have studied hypoxia in heart disease and now focus our efforts on hypoxic tumor cells. We use a multi-culture cell chip for low-shear culture, gradient formation, and spectroscopic diagnostics. We are currently exploring the role of oxygen in cell survival mechanisms as potential therapeutic targets. We have also pioneered several single-molecule and correlation methods for single-cell analysis. This project deals with the development of a new spectroscopic probe and single-molecule measurements in static or flowing cells for rapid assessment of protease activity. Working with Michael Mayer's group at TTU, we synthesized a new protease probe based on the Nile Blue derivative 9-di-3-sulfonyl-propyl-aminobenzo[a]phenoxazonium perchlorate (2SBPO). This new probe, combined with our single-molecule measurements, has radically changed the temporal resolution of apoptosis analysis. Our group also has a strong presence in the cell separations community. We have published a series of papers dealing with geometric effects in fluid flow and their influence in affinity cell capture. We utilized these geometric effects to create a chip that has three-dimensional flow (a multi-inlet chip) for enhanced cell capture using negative selection. Negative cell selection approaches are often preferable in cell sorting, as no labeling of the target cell is required. We are currently developing a new class of microfluidic chips aimed at simple and reliable medical diagnostics.

近期论文

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G. Khanal, S. Hiemstra, D. Pappas, "Probing Hypoxia-Induced Staurosporine Resistance in Prostate Cancer Cells with a Microfluidic Culture System," The Analyst139, 3274-3280 (2014) H. Somaweera, A. Imbramuov, D. Pappas, "Generation of a chemical gradient across an array of 256 cell cultures in a single chip," The Analyst, 138, 5566-5571 (2013). D. Iyer, R.D. Ray, D. Pappas, "High temporal resolution confocal fluorescence measurements for ultrasensitive detection of early stage apoptosis," The Analyst, 138, 4892-4897 (2013). Y. Gao, P. Li, D. Pappas, "A Microfluidic Localized, Multiple Cell Culture Array using Vacuum Actuated Cell Seeding: Integrated Anticancer Drug Testing," Biomedical Microdevices, 15, 907-915 (2013). P. Li, Y. Gao, D. Pappas, "Multi-Parameter Cell Affinity Chromatography: Separation and Analysis in a Single Microfluidic Channel," Analytical Chemistry, 84, 8140–8148 (2012). M. Dong, M.M. Martinez, M.F. Mayer, D. Pappas, "Single Molecule Fluorescence Correlation Spectroscopy of Single Apoptotic Cells Using a Red-Fluorescent Caspase Probe," The Analyst, 137, 2997-3003 (2012). P. Li, Y. Gao, D. Pappas, "Negative Enrichment of Target Cells by Microfluidic Affinity Chromatography," Analytical Chemistry, 83, 7863–7869 (2011). G. Khanal, K. Chung, X. Solis-Wever, B. Johnson, D. Pappas, "Ischemia/Reperfusion Injury of Primary Porcine Cardiomyocytes in a Low-Shear Microfluidic Culture and Analysis Device," The Analyst, 136, 3519-3526 (2011). P. Li, Y. Tian, D. Pappas, "Comparison of Inlet Geometry in Microfluidic Cell Affinity Chromatography," Analytical Chemistry, 83, 774-781 (2011).