Expected Graduation: Spring 2011
Degree Objective: Ph.D. in Physical Chemistry
Other Degrees: B.A. in Chemical and Biomolecular Engineering; Associate of Science, Chemistry; Associate of Science, Pre-Engineering
Gareth Sheppard, a doctoral student in chemistry, dreams big. After all, the outcomes from his research could eventually combat diseases in Third World countries, detect toxins in foods and improve medical drug screening.
However, to reach these mighty goals, Sheppard is starting as small as possible.
"I am working to improve our fundamental understanding of chemical interactions," said Sheppard. "I then aim to provide a means to transfer these methods onto the industrial scale."
"I want to bridge the gap between the two."
Sheppard is part of UGA's Nanoscale Science and Engineering Center, an interdisciplinary research center that brings together nanotechnology scientists. NanoSEC provides UGA scientists with access to areas like the clean room, a facility where biological devices are engineered at the atomic, molecular and macromolecular levels.
Sheppard and Dr. Jason Locklin, his advisor, use their nano-sized experiments and advanced equipment to uncover the nature behind chemical and biological processes.
The two researchers blend elements of chemistry, physics, biology and optics in their complex research on an incredibly small scale. In fact, dust particles can be tens to hundreds of times larger than their nanotechnology devices and tools.
"In combining and improving upon current works, I want to further enhance our ability to track chemical kinetics – the rates of chemical processes – and binding events by using methods that do not require direct interaction with the materials of interest," Sheppard said.
Sheppard's dissertation research focuses on a phenomenon called surface plasmon resonance, a method that indirectly measures the energy absorption of material on a metal, usually gold or silver.
Sheppard uses surface plasmon resonance to detect trace amounts of biological and chemical compounds, including molecules, DNA strands or proteins.
"Using thin layers of metal – about 50 nanometers thick – and a polymer designed to specifically react with a desired target, we can make a device that uses light as a probe for detection," explains Sheppard.
One nanometer is equal to one billionth of a meter. A human hair is about 80,000 nm wide.
Sheppard creates nanotechnology devices – called polymeric scaffolds – to capture targeted compounds. For example, certain proteins can test for the presence of specific DNA strands by attaching at the DNA's binding site.
"Proteins look for certain sequences within the DNA to attach to," said Sheppard. "Typically these proteins replicate – or 'read' – the DNA to produce RNA that can then produce other proteins."
"Other sequences in the DNA tell the bound protein to release."
By exposing polarized light at specific angles to gold, Sheppard can trigger electromagnetic waves, or, as he puts it, a "spiking of energy."
Sheppard indirectly measures the energy absorption of these waves to detect the targeted compound, whether it is DNA, proteins or toxins.
After graduation, Sheppard plans to take his expertise to private industry.
"Eventually, I'd like to bring my methods to industry to track a production line's quality to monitor the progression of a chemical reaction," he said.
Sheppard has the opportunity to apply his research into many settings, including the food and medical industries where the process could be employed as a toxin-screening procedure. Using surface plasmon resonance, Sheppard can detect miniscule levels of toxic chemical compounds.
"Meat produces E. coli, and E. coli makes proteins. We can then test for the presence of these proteins," said Sheppard.
However, Sheppard's ultimate goal concerns toxin detection in humans.
Early disease detection allows medical practitioners to diagnose patients before they show visible signs of a disease. This may mean that patients can be treated before the incubation period has passed and before showing clinical signs of the disease.
"My biological sensing devices can be used to test for biological and chemical toxins in concentrations well below the toxicity threshold and provide an early warning detection for infected patients when a cure may still be available," said Sheppard.
Sheppard eventually wants to find ways to improve the effectiveness of early screening for shiga toxin, a toxin produced by E. coli bacteria. Shiga toxin is commonly found in Third World countries, but early detection of shiga toxin is difficult and expensive.
His advances with surface plasmon resonance could improve the efficiency of shiga toxin screening while reducing the cost. Ultimately, the method may save lives and improve medical care for people living in underdeveloped nations.