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Research with Dr. Tom Betts

A Sugar Sensor Based on Gold Nanoparticles

Jessica PietruchBy modifying the surface of gold nanoparticles with a group that binds both sugars and a fluorescent dye, we are working on creating a sugar sensor. As sugars bind to the surface of a gold nanoparticle, the fluorescence characteristics of the surface-bound fdye change, and we can assess sugar Au Nanoparticle Derivativeconcentrations. Students working on this project get experience  synthesizing, derivatizing, purifying, and evaluating gold nanoparticles. Several students have synthesized groups to help stabilize the gold nanoparticles in aqueous solutions. There are plenty of opportunities for students to independently solve research problems, and gain in-depth experience using  fluorescence spectroscopy, UV-Vis absorbance spectroscopy, infrared spectroscopy, nuclear magnetic resonance and high performance liquid chromatography.

HPLC Analysis of Hops

HopsHumuloneHops have been used for centuries to flavor brewed beverages. The compounds present in hop flowers that are responsible for imparting bitter flavors to these beverages are a class of compounds known as alpha-acids. The alpha acids contained in hop flowers are not extremely bitter, but when they are heated in boiling wort, a portion of the alpha-acids are isomerized (undergo a structural rearrangement) to extremely bitter compounds known as iso-alpha-acids.

Hops ChromatogramIn order to brew beverages consistently, many variables must be controlled. One of those important variables is the amount of alpha-acids that are added to the wort. Most published methods for the analysis of hops by high performance liquid chromatography require approximately 30 minutes to run one sample. We wanted to analyze hops as a lab in one of our analytical courses, so we developing and evaluated a method to analyze hops by HPLC in a much shorter time frame. Our group was able to reduce the analysis time from approximately 30 minutes to under 7 minutes.
Students studying hops

Using Fluorescence to Monitor Epoxy and Nail Polish Curing on Surfaces

DMANSThe basic idea is to add a fluorophore to the sample whose fluorescence depends on viscocity. We added a compound 4-dimethylamino-4'-nitrostilbene (DMANS) to an epoxy that is capable of twisting when dissolved in a fluid medium. As the epoxy cures, the matrix becomes more rigid and prevents DMANS from twisting. Emission SpectraWhen DMANS is in a rigid state, it glows brightly when exposed to blue light. This is why we see the emission increase with time while DMANS is in a curing epoxy.

Fluorescent DeviceWe constructed a homemade device that shines light from a blue LED on a surface (with epoxy or nail polish on it). The fluorescence from the surface passes through an optical filter before it reaches a photodiode that measures the intensity of the fluorescence.

Fluorescence Data