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