Different concentrations of solute added and subsequent rates of freezing.

Courtesy of Kieran Loehr '20

Different concentrations of solute added and subsequent rates of freezing.

November 5, 2018

Student Spotlight on Kieran Loehr ’20: Researching Optimal Cooling Methods

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While cryogenics is often depicted as a scientifically fictitious, Hollywood creation, Kieran Loehr ’20 and peer researchers in the lab of Prof. Robert Thorne, physics, are collaborating to make bio preservation an easy and affordable process.

According to Loehr, freezing humans to be resuscitated in 100 years is not a foreseeable feat, but improving freezing techniques for commercial use, like sperm and egg cryopreservation and biomaterial storage for research purposes, is the lab’s primary goal.

“Tissues, which are composed of membrane bound cells, are particularly delicate and the harsh process of freezing can cause them to rupture and incur damage,” Loehr said. This happens when the molecules of a slowly cooling liquid rearrange into rigid, crystalline structures and disrupt cell membranes. However, according to Loehr, “if the rate at which the freezing process takes place is increased to 600,000 kelvin/sec, biological damage can be avoided due to glass formation.” Glass is a term used to describe a frozen solid composed of molecules that are arranged as if in liquid state.

Loehr says glass appears completely transparent and can safely preserve biological tissues without causing damage. While the science seems simple, devising a method to freeze something at 600,000 kelvin/sec, in a normal lab setting, is almost impossible. But thanks to the fundamental laws of physics and chemistry, there are techniques to solving this dilemma, techniques that Loehr has been dedicating his research efforts to for the past year.

“If you mix in other solutes or chemicals, optimal cooling becomes easier,” he said.

This is because the added solute molecules create interactions with the solvent molecules, preventing them from rearranging into damaging ice crystals.

For example, Loehr said that “adding methanol to the solution decreases the optimal cooling rate to 100 kelvin/sec a much easier standard to achieve, in a Cornell physics lab, with generic liquid nitrogen.”

Loehr has been looking, specifically, at adding varying protein concentrations to solvents to achieve this same effect.

According to Loehr, a typical set up of experiments consists of creating a solution with varying concentrations of protein, preparing sample tubes, threading a thermocouple (tiny thermometer) through each tube, plunging the samples into liquid nitrogen, and then qualitatively observing the state of each solid. If the sample looks transparent and homogenous, like a liquid, it has achieved glass state, and if it looks like ice, with visible crystal structures, it failed.

Currently Loehr is working with a protein called lysozyme, a molecule found in egg whites. The lab is also studying the freezing effect of structurally disordered proteins like those found in tardigrades. Tardigrades are microscopic organisms that can be frozen, resuscitated, and according to The Washington Post, survive in very inhospitable conditions including space.

By examining the behavior of tardigrades and experimenting with the specific proteins found within them, Loehr and colleagues hope to perfect bio-freezing techniques to be used commercially.

“My research is an intersection between chemistry, physics, and biology: all topics related to my class work … I like that my lab work is an application of my education that also provides me general lab techniques and data collecting skills”.

Although his research may not be straight out of a sci-fi movie, Loehr believes that biopreservation is a critical practice that has a large impact in the broader social and scientific community.