Amanda Haes Ph.D.
Research in our group focuses on the microscopic and spectroscopic analysis of plasmonic nanostructures and their integration with microfluidic devices with potential applications for the development of novel biological sensors.This work is inherently multidisciplinary and draws on skills from analytical, materials, physical and surface chemistries as well as biology and engineering. Our research projects can be divided into three areas and are summarized below.
Enhanced Localized Surface Plasmon Resonance Spectroscopy
The localized surface plasmon resonance (LSPR) is a collective oscillation of the conduction band electrons at the surface of noble metal nanoparticles that develops when incident electromagnetic radiation is of an appropriate frequency. The LSPR is important not only in phenomena such as surface-enhanced spectroscopies and resonant Rayleigh scattering, but also as a sensitive analytical tool itself. The LSPR of noble metal nanoparticles has been used to detect biological and chemical species because of its sensitivity to refractive index changes near the metal surface. This work aims at capitalizing on the sensitivity of the LSPR of nanoparticles with novel DNA surface chemistries. Microfluidic devices, fluorescence imaging, and atomic force microscopy facilitate these investigations.
Detection of Cancer Markers
The link between estrogen and tumor formation was first reported in the 1930s. Since that time, it has become widely accepted that estrogen treatment does, in fact, pose a cancer risk. For example, two such natural hormones, estrone and estradiol, are believed to play a role in the development of breast cancer tumors. These species are metabolized into catechol estrogens, which are then metabolized into catechol estrogen quinones. These final species are hypothesized to be the carcinogenic agents that induce several cancers. Traditional methods to screen these biological samples often require large sample volumes, long separation times, labeling procedures to identify target species, or destroy the sample. For these reason, we are integrating nanoparticles, electrophoretic separations, and Raman spectroscopy to develop a fast-responding and sensitive detection platform for these and other cancer-related targets.
Nanoparticle-Assisted Isoelectric Focusing
Currently, the most widely used technique to analyze complex protein and peptide solutions is two-dimensional gel electrophoresis. This method is a two step process. First, the sample is focused into bands according to their point of neutrality using isoelectric focusing. The second step involves a separation of those species in a second dimension. Recently, the first step of the two dimensional separation has been combined with capillary electrophoresis. The electrophoretic separation mechanism serves to focus the species into concentrated bands making them easier to detect than in their native non-concentrated states. Second, by integrating the device into a capillary, the timescale to separate species based on their isoelectric point decreases dramatically in comparison to the complete two dimensional gel experiments. This work incorporates quantum dots and controlled surface chemistry with capillary electrophoresis and isoelectric focusing for both fundamental investigations of the stability of quantum dots and applications in biosensing.
EducationB.A., Wartburg College (1999); M.S., Northwestern University (2001); Ph.D., Northwestern University (2004); National Research Council Postdoctoral Fellow, Naval Research Laboratory (2004-2006)
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