Chemical Engineering Solves Problems with Computer Simulation

Gennady Gor is becoming a go-to expert at combining the power of chemistry and computers to protect our bodies.

Gor's specialty is molecular simulation of fluids and their interactions with porous materials. "I am interested in coupling between surface chemistry and mechanics. This is the main focus of my NSF Career Award from 2020," he explained.

In addition to his teaching role as an assistant professor in the Otto York Department of Chemical and Materials Engineering, Gor has two new grant-funded research projects. One, from Colgate-Palmolive, is to evaluate how certain toothpastes help people who experience dentin hypersensitivity. The other, from the federal Defense Threat Reduction Agency, is to determine which chemicals could neutralize toxic compounds from chemical weapons.

"Molecular simulations on the one hand allow one to understand microscopic mechanisms of phenomena, and on the other hand, propose an alternative to experimental measurements when experiments are challenging," Gor noted.

Toothpaste manufacturers, he said, have long known how to help the 20% of the world's population whose teeth are sensitive to heat and cold. There are miniscule holes that connect teeth to nerves, so the standard method is to make toothpaste that fills the holes, providing temporary relief. The problem faced by manufacturers is nobody quite knows exactly why it works at the molecular level.

"Often people know it works well, they do clinical trials and they see it works. It's experimental evidence, but that's it — you don't know the physics, you don't know the chemistry and you don't know why it works," Gor said. "The product can be on the market without understanding the microphysics."

By hiring an expert like Gor, whose work is titled Uniqueness of Arginine in CSPR Toothpaste and its Mode of Action, manufacturers hope to solve the mystery. Then they can make other changes to the paste without worrying about accidentally changing the hole-filling chemistry.

Meanwhile, in the military project — Experimentally Validated Molecular Models of Organophosphorus Liquids — Gor is a co-investigator to Distinguished Professor Ed Dreyzin, in their study of how to cancel the fallout from destruction of chemical weapon stockpiles. If a bomb is dropped on a stockpile, "You will destroy it, but you will disperse the nasty chemicals everywhere. The idea is to come up with explosives which will neutralize the agents. This is a problem not only about chemistry but also about aerosols."

"You want to know the properties of these tiny droplets to predict how they behave in certain conditions," such as their surface tensions and viscosities, Gor explained. These factors can't be measured with real weapons because it is too dangerous, but what scientists can do is measure the dispersion of similar chemicals that aren't toxic and use that data to make accurate computer simulations for the real agents.

"At this point, in the beginning of the project, I'm confident that we'll certainly be able to predict the properties," he said, adding that others are working on related parts of the same problem through the defense department's Materials Science in Extreme Environments University Research Alliance, which is led by Johns Hopkins University and also includes Georgia Tech, University of California-Riverside and others. 

Odd as the combination may sound, working with Colgate and the Department of Defense will help create new chemical engineering methods with applications in other fields, Gor said. For example, the toothpaste project could have other implications for interactions between amino acids and any kind of mineral surfaces, while the military work might find usefulness for other types of organophosphorus liquids such as fertilizers.

Both projects started in January, and Gor's interest in solving real-world problems at microscopic levels keeps him enthused about what else may come. "There are many fundamental problems," he said. "This is something which I think is pretty exciting. When you go on a molecular scale, you explain all of this."

Participating doctoral students include Alina Emelianova on the Colgate project and Ella Ivanova for the defense work.