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Jaeseung Hahn

College: Macaulay Honors College | City College
Awards: National Science Foundation Graduate Research Fellowship, 2012

Big Ideas on the Nano Level

As an undergraduate, Jaeseung Hahn (Macaulay Honors College at City College, BE in biomedical engineering, 2012) fabricated smart nanoparticles that could bind to cancer cells, enabling them to be seen via an imaging technique called immuno-surface enhanced Raman spectroscopy. In Raman spectroscopy, a laser shined on a substance generates a unique spectrum of photons, sort of the way a prism turns sunlight into a rainbow.

Heading to Harvard-MIT's joint doctoral program in medical engineering and medical physics with the support of a prestigious National Science Foundation Graduate Research Fellowship, he intends to develop a "theranostic" nanoparticle - one that could be therapeutic and diagnostic.

The fellowship is the most prestigious award a graduate student in the STEM disciplines (science, technology, engineering and mathematics) can receive. Providing $126,000 over three years, it recognizes and supports exceptional students who have proposed graduate-level research projects in their fields.

Medical nanotechnology is a growing area, with many researchers pursuing the goal of helping patients with excruciatingly small devices measuring just 1 to 100 nanometers, or billionths of a meter (by comparison, a human hair spans about 100,000 nanometers).

But Hahn may have a leg up on the competition, because he has already done unique research. In a remarkable achievement, he began work as a freshman with Assistant Professor Yuying Gosser, who directs student research and scholarship at City College's Grove School of Engineering. Supported by grants from the Howard Hughes Medical Institute Science Education Program and the National Science Foundation STEP initiative, she established the Pathways Bioinformatics Center and the Gateway Research Laboratory, which are dedicated to undergraduate research training.

Under her guidance and in collaboration with a professor in China, Hahn studied whether and how andrographolide (a bitter substance derived from a plant that's widely used for medicinal purposes in Asia) inhibits extracellular signaling proteins called ERK2 and JNK3. Gosser says that using specialized software, he "spent day and night to model the interface" of these proteins with andrographolide and determined that it did bind with ERK2, but not with JNK3. This resulted in a co-authored poster that was presented at the VIII European Symposium of the Protein Society in Zurich in 2009.

"This experience as a freshman really helped me realize my interest in science and prepare myself to pursue the career in research," Hahn says.

Utilizing the travel grant awarded to Macaulay students and with the support of DAAD RISE, an international program that supports undergraduate scientific research, he interned in the summer after his sophomore year at the University of Osnabrueck in Germany. Researchers there were seeking to use nanoparticles to diagnose cancer, and Hahn got interested in medical nanotechnology right away.

"I developed nanostars, star-shaped nanoparticles that were coated with Raman-active molecules," by adding silver nitrate to the growth phase of gold nanoparticles, he says. This made spherical nanoparticles branch into stars. "They had been synthesized before, but they were never biocompatible because they used toxic chemicals. I somehow was able to add biocompatibility."

He taught German PhD students in the lab to use his process, "then I came back home. The German group published the article," giving him credit.He applied to Memorial Sloan-Kettering Cancer Center, where Gosser had conducted research. As a junior and senior, Hahn worked with researchers Daniel L.J. Thorek (bioengineering) and Jan Grimm (radiology), providing them with expertise in fabricating gold nanoparticles.

"For the past year, I have been trying to optimize the nanostars," he says. They could become "theranostic" devices, delivering drugs and helping to diagnose diseases. "In order for this technology to be translated to the clinical setting, first you have to be able to track and steer the nano-devices to the right place," Hahn says.

Tackling the first issue, Hahn found that star-shaped nanoparticles produced stronger signals under Raman spectroscopy than round ones. But if the nanoparticle is too branched or spiky, the Raman signal fades. "I created a library of them that are not so spiky. The ones that are in the middle, between round and spiky, give out the strongest signal. That's where I am now." Hahn is the lead author, with Thorek, Grimm and another researcher, of a paper about this, which is under revision for publication.

As for steering the nanoparticles to where they're needed, perhaps with an external magnetic field - that remains for future research. (Click on for a related larger-scale drug-delivery approach being researched by 2011 National Science Foundation Graduate Research Fellowship winner Lina Mercedes Gonzales.)

Hahn received a stipend that supported him during summer research and for conferences from COURT, the CCNY-Memorial Sloan-Kettering Continuum of Undergraduate Research Training.

Hahn was born in the United States to Korean parents and was raised in Korea. He spent time in Belgium as a middle- and high-school student before finishing high school in Ossining, N.Y. He then headed for CUNY.

Macaulay Honors College, he says, provides "great opportunity. I could not have done the research in Germany if I didn't have the $7,500 for an internship or study abroad." Meanwhile, City College's Grove School of Engineering "has a reputation for biomedical engineering."

"My Korean education gave me the discipline I have now, so I can be a hard worker and try my best when working in the lab," he says. "At the same time, in America, there is a freedom that's restricted in Korea, which allows people to excel."