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Jack Cahill: Evidence of things unseen

  • Jack Cahill of ORNL’s Biosciences Division is developing new techniques to view and measure the previously unseen to better understand important chemical processes at play in plant-microbe interactions and in human health. Credit: Carlos Jones/ORNL, U.S. Dept of Energy

  • Jack Cahill of ORNL’s Biosciences Division is developing new techniques to view and measure the previously unseen to better understand important chemical processes at play in plant-microbe interactions and in human health. In this photo, Cahill is positioning a rhizosphere-on-a-chip platform for imaging by mass spectrometry. Credit: Carlos Jones/ORNL, U.S. Dept of Energy

  • Jack Cahill of ORNL’s Biosciences Division is developing new techniques to view and measure the previously unseen to better understand important chemical processes at play in plant-microbe interactions and in human health. Credit: Carlos Jones/ORNL, U.S. Dept of Energy

  • Jack Cahill of ORNL’s Biosciences Division is developing new techniques to view and measure the previously unseen to better understand important chemical processes at play in plant-microbe interactions and in human health. In this photo, Cahill is positioning a rhizosphere-on-a-chip platform for imaging by mass spectrometry. Credit: Carlos Jones/ORNL, U.S. Dept of Energy

John “Jack” Cahill is out to illuminate previously unseen processes with new technology, advancing our understanding of how chemicals interact to influence complex systems whether it’s in the human body or in the world beneath our feet.

Since J.J. Johnson assembled the first rudimentary mass spectrometry system that would discover the electron in the late 1800s, scientists have devised ways to see and measure the invisible. Cahill’s work as an analytical chemist at Oak Ridge National Laboratory continues along that path. He and his colleagues developed a porous rhizosphere-on-a-chip platform that mimics the dark underground environment around plant roots for insights into ecosystem health and soil carbon sequestration. The platform, called ChemSitu, was patented and won a 2020 R&D 100 award.

Cahill’s rhizosphere work focuses on amino acid distribution and how that plays into the colonization of root systems by beneficial microbes. Such interactions affect physical traits in plants, including their growth and resistance to disease and pests as well as how much carbon they transmit into soils.

The work illustrates a unifying theme in Cahill’s research: developing technologies to enable chemical analysis in challenging environments. Another of his co-inventions is a single-cell dispensing system for liquid extraction mass spectrometry called CellSight that deepens our understanding of each cell’s unique chemical profile. CellSight earned an R&D 100 award in 2019.

A better understanding of the chemistry of each cell can advance cancer treatments, he said. “There is a certain fraction of cancer cells that survive today’s therapies. We want to examine the small molecules present in those surviving cells and how they change in response to different conditions. The goal is a better drug delivery system,” Cahill said.

He also worked with ORNL colleagues to develop a liquid extraction mass spectrometry technique to speed enzyme analysis as scientists pursue an efficient and cost-effective process to break down polymers in plant lignin residue from biorefineries. The technique has the capacity to run thousands of samples in a day, a process that can be adapted to accelerate research from how plants and microbes interact with each other to how chemical systems change over time, to how drugs are discovered, he said.

Pursuing studies in chemistry, philosophy

Cahill grew up in the small farming town of Franklin Grove, Illinois. Attracted to a variety of subjects, including art and drawing, he credits a high school chemistry teacher for awakening an interest in science. “His class was very difficult; he was known as a challenging teacher. But I was able to achieve a level of understanding in that class that didn’t come across in my other subjects.”

He went on to earn dual bachelor’s degrees at St. Ambrose University in Davenport, Iowa, in chemistry and philosophy, the latter with a concentration in ethics. His first research experience came through a National Science Foundation internship that took him to North Carolina State University, where he developed and applied nanostructured surfaces to examine tissue samples using cutting-edge mass spectrometry imaging. That internship “was the main reason why I even looked at going into grad school,” Cahill said.

As a postgraduate, Cahill used single particle time-of-flight mass spectrometry in his atmospheric aerosols research at the University of California San Diego. He earned a doctorate in chemistry from UC San Diego in 2014.

While searching for a postdoctoral position, Cahill set his sights on institutions developing new techniques in mass spectrometry. He found what he was looking for at ORNL, where the work of chemist Gary Van Berkel captured his attention. Cahill began working as a postdoc with Van Berkel on a mass spectrometry and laser spectroscopy team and was hired three years later as staff. Today, Cahill works in the Bioanalytical Mass Spectrometry Group in ORNL’s Biosciences Division.

Altering how science moves forward

Why is ORNL a good fit for him? “It’s a little bit of everything,” Cahill said. “We have excellent instrumentation here that’s hard to come by anywhere else. And we have a diverse range of very challenging projects where I can fit in and be impactful. Not just measuring things, but pushing new analytical perspectives.”

“We can tackle really difficult challenges that require expertise across a wide range of fields at ORNL,” Cahill said. “We have experts in plant science and analytical science; we have people from all different fields who all work together on the same problem.”

Away from the lab, Cahill enjoys woodworking. He also volunteers for the “Let Her Speak initiative, a non-profit his wife Catherine Porth founded to create a positive, affirming community among women leaders in Knoxville.

“Catherine’s work with Knoxville entrepreneurs has fueled my own business insight,” Cahill said.

He is eager to see the lab’s innovations make their way to the marketplace for the greatest impact. Cahill, Van Berkel (now retired) and Vilmos Kertesz won a Federal Laboratory Consortium Excellence in Technology Transfer Award in 2022 recognizing licensing of their patents to industry. Cahill also presented the ChemSitu Microfluidic Imaging platform at this year’s ORNL Technology Innovation Showcase.

Looking ahead, Cahill is eager to continue devising ways to see and measure the unseen. “A lot of times when you have these empirical measurements being made for the first time, they show you things you didn’t know and probably could not have predicted otherwise,” he said. “So that’s the exciting part for me — generating images and data that show things you can’t see any other way. It changes how you think, it can generate new hypotheses and it can alter the way science moves forward.”

UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. — Stephanie Seay