Green REU Project Descriptions for 2014

Project #1: Multidisciplinary: Polyfunctional triazole ligands synthesized by green click chemistry for use in environmental remediation, Dr. Renee Henry (Bioinorganic), with Dr. Allen M. Schoffstall (Organic) and Dr. Braun-Sand (Biophysical)

The EPA 2007 priority list of Superfund contaminants lists arsenic, lead and mercury as the top three of 275 hazardous substances. Unlike volatile organic compounds, metals are not removed from the environment by natural decay processes. Instead, these need to be removed from the environment to yield safer health and ecological conditions. This research project seeks to synthesize a novel polycarboxylate oligomer in order to bind and remove heavy metals from the environment. The oligomer can be recovered for re-use, which is a guideline set by the EPA for Sustainable Chemistry. The research goals of this project are to 1) synthesize triazole oligomers (Drs. Henry and Schoffstall) with multiple binding sites to remove metals from soil and water, and 2) separate and recover the oligomers from the complexes for reuse. We use green click chemistry to build new triazole systems. They are to be used in metal binding studies (Dr. Henry) and enzyme binding studies (Dr. Braun-Sand). These reactions are carried out in aqueous solvents at 60 oC using microwaves.  

Project #2: Analytical: Analysis of chlorogenic acid in peach skins, Janel Owens (Analytical)

The secondary plant metabolite chlorogenic acid had potential as a chemopreventive agent from the diet, owing to high growth inhibition on estrogen-independent breast cancer cells (MDA-MB-435) with low toxicity to normal cells. Our goal is to use green extraction procedures that were developed by the 2013 REU students for chlorogenic acid from foods. We'll use these extraction protocols to evaluate concentrations in fruits that have been grown under organic versus conventional agricultural practices using a 'market basket' survey approach. These collected data will indicate the effect, if any, of cultivation mode and pesticide concentrations chlorogenic acid content in various foods (peaches, apples, pears, coffee). A second part of this project will focus on the relationship between applied pesticide concentrations and chlorogenic acid concentrations in foods.   

Project #3: Bioanalytical: Investigation of endocrine disrupting compounds in toddler products and river and tap water using micellar electrokinetic chromatography and microfluidic systems, Dr. David J. Weiss (Bioanalytical)

Bisphenol A (BPA) is an endocrine-disrupting compound (EDC) found in plastic containers, epoxy resins which line food cans, and dental resins. It acts as a synthetic estrogen and has been observed to increase the rate at which puberty is reached in mice even at low doses. In addition, high BPA serum levels in pregnant women have been linked to repeated miscarriage. Infants and toddlers are particularly susceptible to the effects of compounds such as BPA on their development and there has been much concern regarding infant exposure and baby bottles. Recently, BPA has been found in liquid infant formula and baby food from glass jars as well. We plan to focus on toddler products, to determine how much BPA and other EDCs a child could be exposed to daily. We hypothesize finding BPA and other EPCs in local river and tap water and plan to investigate the presence of EDCs via capillary electrophoresis (CE), in conjunction with the surfactant sodium dodecyl sulfate and cyclodextrins, CE in the micellar electrokinetic chromatography (MEKC) mode has been demonstrated to have similar limits of detection as GC/MS for EDCs. We plan to complement this with polydimethyl siloxane (PDMS) based microfluidic systems with electrochemical detection. These microchip systems perform analyses in seconds, are miniaturizable and portable (so can be used on-site), use very small amounts of solvents, and are more environmentally friendly than traditional analysis systems.  

Project #4: Physical: Kinetic analysis of inter- and intra-chirality bundling in single and few chirality suspensions of single walled carbon nanotubes, Dr. Kevin Tvrdy (Physical)

Single walled carbon nanotubes (SWNTs) are earth-abundant nanoscale materials that can have metallic or semiconducting electronic properties, allowing them to be used as building blocks in nanoelectronic, photovoltaic, chemical sensing, and biological imaging schemes.  However, because of the techniques used for bulk SWNT synthesis, nanotubes of multiple chirality (chirality = electronic type and bandgap) are simultaneously grown, resulting in the need to post-synthesis separate SWNT in order to both understand and fully utilize their chirally unique properties.  While one focus of the Tvrdy lab at UCCS is to better understand and improve this separation process, a consequence of successful SWNT separation is the generation of few or single chirality samples with limited shelf life, which could potentially restrict the use of this otherwise widely applicable and novel material.  In order to extend the shelf life of separated SWNT, it is first necessary to quantify the process which limits their stability: SWNT bundling, which can be described using colloidal stability models.  The collective kinetics which describes such processes is dependent on temperature, solvent, the presence of ions, and the choice of surfactant stabilizer.  A full understanding of the chirality-dependent bundling of SWNT will elucidate parameters which maximize material stability and allow for greater uses of separated SWNT materials.  Project participants will learn basic theory pertaining to nanoscience, gel-based single-chirality SWNT separation techniques, SWNT bundling quantization schemes, spectroscopic and imaging analysis of nanomaterials, and modeling of experimentally obtained spectra and kinetic data. Any questions about this project should be directed to Dr. Kevin Tvrdy,

Project #5: Biochemistry:Hexokinase Project, Dr. Sonja Braun-Sand and Dr. Wendy Haggren (Biochemistry)

Targeted drug development is an approach that begins with the identification of a protein, a target, which functions abnormally and causes disease. A drug is then developed that targets the protein, alters its abnormal function, and treats the disease.  Essential to this approach is a thorough understanding of the target protein's structure. Our target, hexokinase, is found in all cells. It takes glucose that has entered cells from the blood and converts it into a form that is trapped in the cell. The trapped glucose can be used by the cell for energy production or for conversion to stored fuel. When hexokinase functions abnormally, it has been implicated in some cancers and diabetes. Our research group uses the yeast hexokinases as a model for the human hexokinases, and employs a multi-disciplinary approach to correlate hexokinase structure to its function. Our group has already introduced three mutations into the gene encoding yeast hexokinase I. REU students working in our group will apply molecular biological tools to optimize the expression of the wildtype and mutant hexokinase enzymes in yeast cells, then analyze their activity using ultraviolet-visible spectroscopy to characterize the effect of the mutations. This approach will allow us to make greater advances in correlating structure to function of this protein believed to be critical to the progress of diabetes and some cancers.