Our ResearchOur research involves fundamental studies in 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, particularly bioanalytical chemistry, some of our studies emphasize the more specific areas of environmental analyses and nanomaterials.
Several ongoing research projects involve varying degrees of chemical, instrumental, and data reduction strategies (chemometrics) for the analyses of complex systems. Selected examples include:
- development of separation strategies using ionic liquids;
- development of novel analytical schemes for protein separations;
- 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.
Several projects are relevant to the general area of organized media. One type of organized media frequently used in our research is molecular micelles, which 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 typically exist in the α, β, and γ forms, are cyclic oligosaccharides whose torus shaped structures allow size selective binding of hydrophobic molecules. Cyclodextrins have also been employed in strategies for 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. We are also developing a new variation of sodium dodecyl sulfate poly-acrylamide gel electrophoresis (SDS-PAGE) which we believe may have great utility for protein characterization, particularly glycoproteins.
We have recently embarked on the development of new kinds of nano- and micro-particles which are developed from a group of uniform materials based on organic salts (GUMBOS). We believe that these GUMBOS represent a true breakthrough in micro- and nano-technology` since they can be designed for specific uses, rather than simply adapted for a particular use.
Various Types and Combinations of Properties of GUMBOS for Biomedical Applications.
We have also demonstrated a novel approach to tune the spectral properties of our fluorescent nanoGUMBOS with potential for applications in photovoltaic and optoelctronic devices.
As an example of an application of our GUMBOS, we have developed novel magnetic, luminescent, and cancer-targeting lipophilic phosphonium-lanthanide salts. The dysprosium-thiocyanate anion of these compounds is intrinsically paramagnetic and luminescent, which provides great utility for applications such as targeted delivery under the influence of a magnetic field, as well as fluorescence imaging of tumor cells. Simultaneously, the lipophilic phosphonium cation serves as a mitochondrial targeting agent, which is quite selective for tumor cells. We have investigated the application of these compounds as tumor-targeting and imaging agents in human cell cultures. The figure below demonstrates that after incubation of cancer cells with a solution of our phosphonium-dysprosium compound and excitation at the appropriate wavelength of light, a yellowish-green fluorescence is observed which corresponds to the emission of Dy3+. In addition, our compound was observed to
exhibit significantly lower IC50 values against carcinoma cell lines as compared to normal cell lines, suggesting great selectivity toward cancer cells.
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. Another 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.
Another of the research projects in our research laboratory involves the characterization of human athero¬sclerotic 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.
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