Tiny nanostructures help URI doctoral candidate in chemistry detect chemicals in Narragansett Bay

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Buddini Karawdeniya
Buddini Karawdeniya, a doctoral student in the Department of Chemistry at the University of Rhode Island. Photo submitted by Shaun Kirby.

KINGSTON, R.I., —March 29, 2018—When Buddini Karawdeniya was a middle school student in Sri Lanka, she didn’t want to make the same, boring atom model that her peers constructed year after year.

Instead, she arranged lids of different sizes to represent energy levels, along with paper clips to depict electrons, to create a 3D model of a nitrogen atom her teacher had never seen before.

“She was so ecstatic,” says Karawdeniya, who is preparing to defend her Ph.D. dissertation for the chemistry department at the University of Rhode Island. “She said, ‘Buddini, don’t stop at just a degree.’ I didn’t know what she meant at that point, but after completing my college degree, I felt like I could do something more.”

So Karawdeniya and her husband, Nuwan, took the 30-hour trip from their home in 2012 to Rhode Island to work with Associate Professor of Chemistry Jason R. Dwyer. They study the science behind nanostructured sensing platforms that can detect molecules of chemical or biological origin, from nitrates in water to biomarkers in the human body. Dwyer is also a researcher for the Rhode Island Consortium for Coastal Ecology Assessment, Innovation & Modeling.

Karawdeniya has been fabricating such platforms as part of her dissertation for a technique called Surface-Enhanced Raman Spectroscopy, or SERS.

“The Raman signal by itself is too weak, but a metal layer as thin as a nanometer in the vicinity of the molecule can enhance the Raman signal by a million-fold,” she says.

Figuring out the techniques and support materials to make specific gold nanostructure shapes and sizes needed to fabricate chip-like surfaces called substrate to identify certain molecules through SERS is a major part of the scientific process, however. Once fabricated, researchers can add a sample to the chip or soak it to take readings.

“They are all very sensitive and can detect very low concentrations,” says Karawdeniya. “We can custom-make different shapes and sizes of nanostructures by using the same technique on different supports like silicon nitride, paper and silicon. We use a technique called electroless plating, and we don’t need sophisticated instruments for it, not even a power supply.”

The benefit of such nanostructures, and the reason Karawdeniya is collaborating with Dwyer and others with the coastal ecology consortium, is to develop new substrates that can rapidly detect specific nutrients, contaminants and biomolecules in the waters of Narragansett Bay.

For Karawdeniya, conducting research has been the easy part of living in a new country, thanks to Dwyer and her colleagues.

“Everyone has been supportive here,” she says. “Professor Dwyer is a tough but great mentor with high standards and superb research ideas. He pays so much attention to his grad students and their future. I am so grateful I work for him.”

Adjusting to life in the United States, however, was more of a challenge. In America, professors are more approachable and helped Karawdeniya, who did not know of many Sri Lankans living in Rhode Island at the time, she says.

“When I went to the supermarket, I was like, ‘Wow, this is huge,’” she says. “I remember trying new food was an interesting experience. I was used to 80-degree weather throughout the year before I came here, so cold weather was an entirely new experience for me. Living in a new place, finding furniture, finding transportation and adjusting to a new culture took some time, but not as long as I expected thanks to the few Sri Lankans we met and our host family.”

After Karawdeniya defends her dissertation, she wants to pursue postdoctoral studies or gain industrial experience. Although unsure about when she will return to Sri Lanka, Karawdeniya hopes to eventually teach in college and use knowledge of nanostructures and Raman sensing to help solve environmental and medical issues back home.

“If students learn the right concepts and get the right inspiration, that feels so good,” she says. “I would love to develop paper-based sensors, which in a third world country like Sri Lanka, would go a long way.”

The Rhode Island Consortium for Coastal Ecology Assessment, Innovation and Modeling is a five-year, $20 million initiative funded through the Rhode Island National Science Foundation Established Program to Stimulate Competitive Research. The initiative seeks to develop technological infrastructure to predict and respond to the changing interactions between chemicals and lifeforms in the waters of Narragansett Bay.

For more information, visit https://web.uri.edu/rinsfepscor.

This release was written by Shaun Kirby, communications coordinator for RI C-AIM and Rhode Island EPSCoR.