Synthetic Fish Blood Could Be Used As Antifreeze
Fish that live at the poles have proteins in their blood that prevent it from freezing.
Anyone who has experienced freezer burn knows that ice crystals can be a problem at low temperatures. Ice crystals’ jagged edges can do more than just ruin the texture of your ice cream, however. At a microscopic level, they can destroy the structure of living cells or biological medicines, like enzymes and antibodies, which nevertheless must be stored at low temperatures for preservation.
The antifreeze in your car — ethylene glycol — is toxic, so isn’t a solution for foods or drugs. Instead, researchers have turned to nature for inspiration: fish that live at the poles have proteins in their blood that prevent it from freezing.
Now, researchers from the University of Utah’s John and Marcia Price College of Engineering have devised a way to make a stripped-down, synthetic version of that protein, simple enough to be manufactured at scale, but powerful enough to inhibit the formation of ice crystals at sub-zero temperatures.
The researchers demonstrated the effectiveness of their mimic polypeptides on several real-word test cases, including ice cream and the anti-cancer drug Trastuzumab. The former was successfully chilled down to -20°C, while the latter survived temperatures as low as -197°C.
The study, funded by the National Science Foundation, was published in the journal Advanced Materials. It was led by Jessica Kramer, an associate professor in the Department of Biomedical Engineering, and Thomas McParlton, a graduate student in her lab. Their coauthors include lab members Charles Osborne, Ke Wang, and Rachel Detwiler, as well as Konrad Meister, assistant professor at Boise State University’s Department of Chemistry.
For decades, researchers have eyed the naturally occurring antifreeze proteins found in certain polar fish, as well as some insects and plants. However, extracting meaningful quantities of these proteins from living organisms is impractical for commercial use due to the cost, as well as the potential for contamination with allergens.
Kramer and her colleagues therefore set off to determine the exact physical and chemical properties of these proteins that were responsible for their antifreeze capabilities. A pair of earlier studies, published in Chemistry of Materials and Biomacromolecules, demonstrated the structural features that were most critical in the naturally occurring proteins.
“Ultimately, we simplified the structure to only the parts we thought were required for antifreeze activity, which makes production less complicated and expensive,” says Kramer. “Despite those changes, this study showed that our mimics bind to the surface of ice crystals and inhibit crystal growth, just like natural antifreeze proteins.”
The researchers tested their protein at temperatures relevant for storing frozen foods, like ice cream, as well as much colder temperatures used when transporting living medicines.
“Best of all,” McParlton says, “we make these mimics entirely using chemistry — no fish or cells required.”
As proof of concept, the researchers demonstrated that the mimic molecules are non-toxic to human cells, are digestible by enzymes of the human gut, and can survive heating, a critical factor for its potential for food production. They also ran tests on sensitive enzymes and antibodies, showing that the mimics protected them from damage associated with freeze/thaw cycles.
“We also showed that we can inhibit ice crystals in ice cream, which often happens during shipping or when people take the carton in and out of the freezer,” says Kramer.
The researchers envision their mimic molecules enabling a wide variety of applications, from extending the shelf life of frozen foods to improving the storage and transport of life-saving biologics. The technology is currently patent pending, and the team is working to bring their innovation to market through a new startup company, Lontra, which aims to commercialize these synthetic antifreeze proteins.
Reference: McPartlon TJ, Osborne CT, Wang K, et al. An ultrapotent, ultraeconomical, antifreeze polypeptide. Adv Mater. 2025. doi: 10.1002/adma.202420504
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