Our activities straddle the boundary of analytical chemistry and biochemistry, providing for a broad range of interesting investigations. A key component in our research program is the study of individual mammalian cells. A cell serves as an intact chemical system, which has the dimensions to allow us to develop and refine analytical measurements at the picoliter scale. Characterizing a heterogeneous population of cells, one by one, is a challenging problem for a chemist to solve. Owing to the low detection sensitivity of conventional analytical or biochemical methods, intracellular chemistry is often measured by sampling an aliquot that is representative of a large population (e.g., millions) of cells. The resulting measurement of such a sample represents an average value, which is then extrapolated to the level of one cell. The drawback with such an approach lies in the assumption that this average analyte measurement is indicative of each individual entity in the population. However, with a strategy that can accommodate the sampling and measurement of a single cell, such ensemble averaging is eliminated. Thus, a new realm of information, formerly not possible with bulk-scale measurements, becomes available.

   Research opportunities consist of projects that are highly biological (e.g., using molecular biology techniques such as reverse transcriptase-polymerase chain reaction (RT-PCR) to study single-cell gene expression), as well as those that involve fundamental analytical chemistry (e.g., exploring electrophoresis behavior of nucleic acids using capillary electrophoresis with laser-induced fluorescence (CE-LIF)). Investigations involving single-cell gene expression are prevalent in our laboratory, and efforts are underway to develop novel analytical approaches to achieve quantitative measurements of gene expression in individual cells, using kinetic-based measurements such as real-time RT-PCR. While quantitative PCR methodology is widespread, it is far from ideal, and we hope to bring an analytical perspective to this important biochemical method. In addition, we are working on developing a microfluidic platform (i.e., chip-CE) to scale down our gene-expression measurements, thus preventing the dilution that is inherent to single-cell reactions with conventional thermocycling. Other projects on the horizon utilizing CE-LIF include examining analysis strategies for single-cell proteins, exploring the electrophoresis behavior of nucleic acids, refining separation conditions for single-cell levels of rRNA and tRNA, developing novel detectors in conjunction with CE separations, and writing programs (e.g., Labview) to facilitate operation of new instrumental approaches.