Vice Chancellor for Strategic Initiative, Boyd Professor and Philip W. West Professor of Analytical and Environmental Chemistry, Howard Hughes Medical Institute Professor
Our research involves fundamental studies in analytical chemistry as well as the development and application of new methods (chemical, instrumental and mathematical), for analytical measurements. The overall goal of these studies is to provide improved methodology for the analyses of complex systems. Although the primary focus of our research is in the broad area of analytical chemistry, some of our studies emphasize the more specific area of environmental analyses. However, most of our studies are in the general area of bioanalytical chemistry.
Several current ongoing research projects involve varying degrees of chemical, instrumental, and data reduction strategies (chemometrics) for the analyses of complex systems. Selected examples of these projects include:
· development of chiral separation procedures using novel chiral polymers;
· development of novel analytical schemes for protein separations;
· characterization of proteins and other biomolecules associated with human atherosclerotic plaque;
· synthesis and production of nanoparticles for novel bio-applications and bioanalytical measurements;
· studies of the influence and applications of guest/host chemistry, e.g., organized media, to chemical systems of analytical interests;
· development and application of spectroscopy, particularly fluorescence, for bioanalytical measurements.
A number of our projects are relevant to the general area of organized media. One type of organized media that we use in our separation studies is molecular micelles. Molecular micelles have many advantages over conventional micelles. They are stable below the CMC (critical micelle concentration), stable to high concentrations of organic solvents, and stable in the presence of molecules such as cyclodextrins. Cyclodextrins, which exist as α, β, and γ forms, are cyclic oligosaccharides whose torus shaped structures allow size selective binding of hydrophobic molecules. Cyclodextrins have also been used in our separation and spectroscopic studies.
We have developed molecular micelles for separations using variations of capillary electrophoresis, including micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC). With regard to the CEC approach, we have used our molecular micelles as anionic components of polyelectrolyte multilayer (PEM) coatings on capillary walls. The figure below is an example of the rapid and efficient separation of four proteins using such an approach as compared to a bare capillary where the proteins would adsorb to the walls and cause poor reproducibility of separations.
Another of the research projects in our research laboratory involves the characterization of human atherosclerotic plaque. This project is in collaboration with Dr. James W. Robinson. Cardiovascular diseases continue to be major causes of death in the developed world and to some extent, in developing countries, despite the great advances in understanding the factors that contribute to heart disease. Previous studies have revealed that, in later years, atherosclerotic plaques are complex lipid deposits, which contain large quantities of cholesterol and cholesterol esters. Our focus in the studies conducted in our laboratory involves trying to understand the differences in plaque associated with diseased arteries and plaque build-up in by-pass arteries. We have used a number of techniques to examine the complex chemistry involved in atherosclerotic plaque formation. These include mass spectrometry, capillary electrophoresis, and gel electrophoresis. We are developing a new variation of sodium dodecyl sulfate poly-acrylamide gel electrophoresis (SDS-PAGE) which we believe may have great utility for our plaque characterization, particularly of glycoproteins.
An example of our recent research (published in Nano Letters in 2008) using frozen ionic liquid nano- and micro-particles is shown in the figure below. We believe that these new types of particles represent a real breakthrough in micro- and nano-technology.
Solid [bm2Im][PF6] microparticles of ~ 3-μm imaged with (a) SEM, (b) Optical microscopy (DIC), (c) Optical microscopy (fluorescence), (d) Overlay of DIC and fluorescence.
A number of other projects are ongoing in the general areas of environmental analysis and nanoparticle synthesis. Briefly, one of the environmental projects involves studies of chiral compounds generated during combustion processes. This study is in collaboration with Dr. Barry Dellinger of this department. One of our nanoparticles projects uses molecular micelles to replace conventional micelles in PLGA nanoparticles synthesis. Use of molecular micelles in the synthesis of these particles results in a more uniform size distribution as compared to those produced with conventional micelles. These particles are currently being investigated as possible new drug delivery systems.
ACS DAC Spectrochemical Analyses Award, 2008
Association of Analytical Chemist (Anachem) Award, 2007
Southern Chemist Award, ACS Memphis Section, 2006
Kamande, Mary W.; Ross, David; Locascio, Laurie E.; Lowry, Mark; Warner, Isiah M. Simultaneous concentration and separation of coumarins using a molecular micelle in micellar affinity gradient focusing. Analytical Chemistry (2007), 79(5), 1791-1796
Yang, Y.; Lowry, M.; Schowalter, C.M.; Escobedo, J.O.; Fakayode, S.O.; Xu, X.; Zhang, H.; Jensen, T.J.; Fronczek, F.R.; Warner, I.M.; Strongin, R.M.. An Organic White Light-Emitting Fluorophore, Journal of the American Chemical Society, (2006), 128, 14081-14092.
Tesfai, Aaron, El-Zahab, Bilal, Bwambok, David, Baker, Gary A., Fakayode, Sayo O., Lowry, Mark, Warner, Isiah M., “Controllable Formation of Ionic Liquid Micro- and Nanoparticles via Melt-Emulsion-Quench Approach,” Nanoletters, 8(3), 897-901, 2008.
Gates, Arther, Fakayode, Sayo, Lowry, Mark, Ganea, Gabriela, Murugeshu, Abitha, Robinson, James, Strongin, Robert, Warner, Isiah, “Gold Nanoparticle Biosensor for Homocysteine Thiolactone-Induced Protein Modification,” Langmuir, 24(8), 4107-4113 (2008).
|Former Ph.D. Students|
Dr. Sharon Neal, Professor of Chemistry, University of Delaware
Dr. Thomas Rossi, CEO and President, Agile Therapeutics, Inc.
Dr. Constantina Kapnissi, Professor of Chemistry, University of Cyprus
Dr. Philip Oldham, Provost and Vice Chancellor for Academic Affairs, Univ. of Tennessee at Chattanooga