Manufacturers rely on columns composed of porous materials for molecular separation in fields such as pharmaceuticals, energy production, chemical processing, environmental science, and food and beverage manufacturing. However, a recent study conducted by researchers at Case Western Reserve University reveals that these separation materials do not perform as effectively as intended due to excessive polymer packing within the pores, leading to inefficiencies and inflated costs.

Lydia Kisley, Ambrose Swasey Assistant Professor of physics and chemistry at Case Western Reserve, employed single-molecule microscopy to uncover that molecules primarily diffuse and adsorb along the outer regions of porous materials, leaving the central sections largely unused. This study, set for publication on Feb. 14 in Science Advances, challenges the way these materials are designed and utilized.

"These materials are marketed as 'fully porous,' but they aren't," Kisley explained. "We were really surprised by this. Why isn't this material working the way it was designed and is being sold to work?"

Working alongside Professors Burcu Gurkan and Christine Duval from the Case School of Engineering's Department of Chemical and Biomolecular Engineering, Kisley sought to understand the root of the inefficiencies.

Using single-molecule fluorescence microscopy, a technique that enables scientists to observe individual molecular interactions at the nanoscale, Kisley was able to visualize the molecular behavior. "We use light to be able to observe individual molecules," she said. "Shining a bluer laser excites the molecules, making them fluoresce in red."

Gurkan and postdoctoral researcher Muhammad Zeeshan initially tested the materials under industry-standard conditions and found they performed as manufacturers claimed. However, when Kisley imaged the same materials under actual separation conditions, she discovered that manufacturers had introduced an excessive amount of cellulose material, effectively blocking the pores. Removing the excess material with a solvent significantly enhanced the separation potential.

Kisley hopes these findings will drive manufacturers to develop more efficient separation materials. "Half the cost of bringing a new drug to market is tied to molecular separation, a process that can be repeated 10 to 20 times for a single substance," she noted.

By applying single-molecule microscopy to evaluate separation efficiency, manufacturers could reduce reliance on trial-and-error methodologies, improving both accuracy and cost-effectiveness in the industry. "Maybe you could get more efficient separations and eliminate an entire step," Kisley said. "Think of the monetary and time savings. We could converge faster on the successful drug to help treat disease."

The study credits Ricardo Monge Neria, a graduate student in physics at Case Western Reserve, for leading the experimental research and paper composition. Additional collaboration came from Rachel Saylor, an associate professor of chemistry and biochemistry at Oberlin College, and researchers from the Case School of Engineering Swagelok Center for the Surface Analysis of Materials.