One of the first truly inspiring things Susan Daniel, Chemical and Biomolecular Engineering, saw in science was not what you might expect. Not a mechanism, not a reaction, not the behavior of a material. “It was watching the expression on my adviser’s face, the excitement,” she says, “when he saw I had done something worthy of Science.”
Her adviser was reacting to a breakthrough in surface science that would go on to be published in Science. “But I didn’t really know I had done something, because I didn’t have the context,” she says. “It taught me that it’s not just looking at interesting things and describing them—it’s knowing where the discovery fits in, so you can be the one to say, ‘Now it all makes sense.’ So you can be the one to say, ‘Eureka!’”
Since that moment, Daniel has sought a broad scientific landscape in which to experiment, discover, and to have an impact. With new imaging technologies and experimental platforms, her lab looks at interfaces between biological materials and phases of matter— how viruses connect to and penetrate the surfaces of our cells, for instance, or how a water droplet moves along a solid surface.
How Viruses Get Inside Our Cells
The membrane of a cell is sort of like a sensory system, Daniel says. In a simplistic picture, proteins on the cell’s surface act as the eyes, ears, nose, and mouth of the cell, coming into contact with what’s around it and sending and receiving signals to enact an outcome. Daniel’s ongoing CAREER grant from the National Science Foundation focuses on how these proteins on the cell’s membrane interact with their surroundings and how that affects their organization and activity.
Not all of the things the cell comes into contact with are friendly—about half of the work in Daniel’s lab investigates how viruses attach to cells and enter them. The viruses that Daniel studies have protein spikes that bind to specific receptor sites on their target cells and pierce the cell membrane open. The viruses then deliver their genetic information, transforming the cell into a virus factory.
With new imaging technology, Daniel can watch a single virus approach and attach in real time. “We now have better cameras, better computing power, and we can get new information with it,” she says. “We’re trying to understand that critical point—what happens at the barrier? Because if the virus can’t get inside the cell, then no infection occurs.”
Figuring out how the viruses differentiate between cell types and what conditions activate and facilitate the fusion are at the top of Daniel’s agenda. “That’s exactly what a drug delivery engineer wants to know, too,” she says, to create new drugs that go directly to their targets and bind.
Daniel works with influenza, Ebola, and corona viruses, the latter of which is responsible for SARS and MERS. Coronavirus is particularly interesting—and dangerous—because it can take advantage of a broader range of conditions and can bind at multiple sites. Daniel collaborates with Gary Whittaker, Microbiology and Immunology, to understand the molecular mechanisms that initiate fusion.
When Cells Encounter Cancer’s Microvesicles
Other unfriendly visitors the cell might encounter are microvesicles released by cancer cells. “These microvesicles interact with cells and get them to produce a more hospitable environment for tumor growth,” Daniel says. “But we don’t know anything about the molecular-scale interactions that initiate this process.”
“I want to inspire the next generation and help them continue this legacy of science and critical rational thinking—and the good it’s done for us, really since the age of enlightenment.”
In a new collaboration with Claudia Fischbach-Tescl, Biomedical Engineering, Daniel is investigating the point of contact. With the help of a seed grant from the Memorial Sloan Kettering Cornell Center for Cancer Nanotechnology Excellence, the two labs have already seen similarities between how viruses and vesicles bind to the cell membrane.
“Mother nature has variations on a theme,” says Daniel. “She’s the ultimate engineer, and there are these common threads. Once we understand the basics of how a virus is able to do the things it does, we might then be able to use that knowledge to understand these other processes, too.”
Why Do We Care about Liquid Drops?
That very first groundbreaking experiment that Daniel conducted as a student involved the oscillation of liquid droplets. She continued this work for her PhD, only moving to biological systems during her postdoctoral fellowship at Texas A&M University. But wiggling liquid droplets was her first love, and her lab continues to explore their properties.
“It sounds sort of strange—that we wiggle the drops and watch them oscillate—like why would you care about that?”
“Because the applications have the potential to impact and improve our daily lives and solve large problems facing society,” Daniel continues. The research applies to any situation in which you have liquid droplets that you want to move—like a rain-soaked windshield. The studies especially apply to improving heat transfer and energy efficiency.
“If you think about a nice cold glass of water on a hot day, you get condensation. So the same process is happening in a heat exchanger,” Daniel explains. “When that hot vapor condenses on a cold surface, you get these droplets forming, and that eventually becomes an insulating film preventing further condensation. If you can remove that film, you can accelerate the process. For a lot of energy management applications, that’s really important.”
In addition to being useful, the experiments are also beautiful. Daniel’s lab shines light from below through a tiny grate and into a glass-plated droplet. “If you’ve ever gotten a drop of water on your phone, you can almost see the pixels—it’s the same kind of thing, but we’re also oscillating the droplet. Depending on the size of the drop and some other things, it will oscillate in these different modes, making all kinds of shapes. It’s my most visually beautiful work—where its beauty inspires scientific investigation.”
Daniel’s work on droplets, first funded by the National Aeronautics and Space Administration (NASA), has gotten the agency’s attention again. In collaboration with Paul H. Steen, Chemistry and Chemical Biology, the two labs hope to put an experiment on the International Space Station in 2018. “Being able to do this work in space has a lot of advantages,” Daniel says. “Because you don’t have to contend with gravity, you can make much larger drops, which allows you to observe what the drop is doing more easily.”
Science, Faith, Beauty
Even as the first person in her family to attend college, Daniel never felt she had to defend her studies to her parents or other relatives. “They’re my biggest fans, and I always had the feeling that they believed in what I was doing and believed in science,” she says. “I’m very grateful for that.”
A faith in and love of science now emanates from Daniel. “Science is beautiful,” she says. “Science transforms our lives, and the hope I have is that, when presented with a problem, humankind will always find a way to solve it. It’s only when people start doubting science, its usefulness and its methods, that we run the risk of not being able to solve the problem.”
Teaching, she adds, allows her to share and pass on the scientific tradition. “I want to inspire the next generation and help them continue this legacy of science and critical rational thinking—and the good it’s done for us, really since the age of enlightenment.”
The interdisciplinary collaboration at Cornell accelerates and amplifies the impact that science can have, Daniel says. “It seems like we have a patchwork of things going on in the lab, but that’s the beauty of being an engineer,” she says. “Once you understand a fundamental set of principles, you can apply that to all kinds of problems. That’s what I think is so fun about science and about being at a place like Cornell, where collaborating with the world’s top scientists and engineers is highly valued.”