Blood? No. Needles? No. Medicine? Yes.

What do two chemistry majors do with their interest in medicine when one has a fear of blood and the other a fear of needles?

Sign up for research.

Haley Murphy ’25 and Ana Katrina “Chinny” Tiu ’25 both knew they didn’t want to become doctors, but they did want to work in the medical field, thanks to real-world experiences. 

During the COVID-19 pandemic, Murphy realized what she wanted to study when she entered college. “The media was overflowing with information about vaccine development and pandemic response and things like that,” she said. “I was introduced to the idea of research as a career, because I didn’t really know that the medical field held anything other than doctors. That being really broadcasted in the news opened my eyes to this alternate career route.”

Meanwhile, Tiu, who is from the Philippines, saw firsthand how big of a problem antibiotic resistance is in her country: “I was thinking about home and I wanted to be a part of a research project that I could see more tangibly in my daily life.”

These experiences led them to a biochemistry concentration at Holy Cross and the lab of Associate Professor Christine Hagan, where the two classmates met. 

Hagan’s lab studies the ways bacteria kill each other using proteins to address the growing problem of antibiotic resistance. Some bacteria produce contact-dependent inhibition (CDI) systems, which they use to kill other similar bacteria. “It’s a mechanism for one bacterial species to take over a little niche in the environment by killing off its competitors,” explained Hagan, who is also co-director of the biochemistry program. The hope is that the lab will identify new methods of treating infections by understanding the process by which the bacteria kill each other. New antibiotic therapies are urgently needed for treating the types of bacteria that CDI systems target, which include widely-known species like E. coli and Salmonella, but also species that more commonly cause infections in hospitals.

Murphy and Tiu started in Hagan’s lab in 2023 as Weiss Summer Research scholars and continued in their junior and senior years. Throughout that time, the lab investigated how CDI proteins inject toxins from one cell into another by developing a way to study this process in isolation in a test tube. Along with lab partner Grace Conroy ’25, Tiu first examined how the toxin is released into a targeted cell, and then later how that toxin breaks through the targeted cell’s membrane, which is difficult for many other molecules, including antibiotics, to do. Building on Tiu’s work, Murphy investigated how the proteins responsible for this process interact as the toxin penetrates the cell membrane. By understanding these steps individually, scientists can “imagine new ways of getting antibiotics through that same membrane,” according to Hagan.

Chinny and Haley’s work significantly advanced our understanding of how CDI systems function, Hagan said, and it also cemented their goals for the future.

“This experience was definitely the defining experience of my Holy Cross education. I don't think at any other school would we have been able to get this hands-on [research] this early,” Murphy said. “Obviously, it taught us so much about the science, but, I mean, I knew going in that I wanted to pursue a Ph.D. Because of Professor Hagan, and because of the Holy Cross chemistry department, this was everything that I hoped it would be, and it just further cemented my goals of going to grad school.”

Tiu agreed, emphasizing the unique experience of undergraduate research at Holy Cross: “The lab is purely undergrads, there's no grad students. So we're not doing any grunt work, we're doing all our projects, we're thinking about them. And Professor Hagan, as a mentor, has been amazing. She's so patient, and she's been with us step by step, making sure that we know what we're doing. We're not just blindly following procedures. And I think it's been such a great experience in the way that I now know what I want to do for the rest of my life.”

Image

Both Murphy and Tiu are pursuing a Ph.D. in chemical biology after graduating from Holy Cross.

As undergrads, Murphy and Tiu were able to also get a taste of what graduate school lab work might be. As rising seniors, Murphy worked as a chemical biology fellow at New York University through the U.S. National Science Foundation’s (NSF) Research Experiences for Undergraduates program, while Tiu was an undergraduate research assistant at the University of Minnesota Twin Cities through the NSF Center for Sustainable Nanotechnology's Summer Undergraduate Research Experience Program. 

“It was actually really valuable that they had both experiences, doing research at an undergraduate institution and also at an R1 university,” Hagan said. “I certainly saw, when they came back from their programs in the fall of their senior year, that both were really excited about those experiences. They had learned different things, different techniques, and that broadened their perspective scientifically. … I saw them mature a lot in that summer, and that helped them to figure out, I think, what they wanted to do more specifically when they went to graduate school.”

And graduate school is indeed where their paths are headed next. Murphy is enrolled in the Tri-Institutional Ph.D. Program in Chemical Biology – a joint program offered by Weill Cornell Medical School, The Rockefeller University and Memorial Sloan Kettering Cancer Center in New York City – to pursue cancer research, a goal she’s held since starting at Holy Cross. “The dream has not died,” Murphy said. “It persists.”

Meanwhile, Tiu is returning to the University of Minnesota for a Ph.D. program and planning to keep an open mind to all the different applications for chemical biology, whether that’s medicine, cosmetics, food, the environment or academia. 

As the two begin their first years of their respective doctoral programs, they both credit their experience in Hagan’s lab for their readiness to step into the unknown in this next chapter.

“The chemistry department has just highlighted the importance of embracing that scientific curiosity without the fear of failure, or the fear of being perceived as someone that doesn't know what they're talking about,” Tiu said. “You’ll never really know. That's the beauty of research. You're doing something that hasn't been done before, so nobody knows.”