With an exciting breakthrough and an ERC Proof of Concept grant in the pocket, Full Professor Ilja Voets reports promising progress in her research on antifreeze proteins. Pioneering the use of the world's most powerful microscope, being the first researcher to operate it at subzero temperatures, she designed novel materials that prevent freezing damage to biological systems. Her dream is to ultimately develop a suitable method for preserving donor organs for more extended periods of time for life-saving operations.
Backed by a prestigious NWO Vici grant in 2024 and a recent ERC Proof of Concept grant, Voets is on a quest to understand how ice damages cells, tissues, and organs and how such damage can be prevented to enable high-quality preservation . By freezing biological systems like cells or organs, you pause metabolism, enabling unlimited storage time.
But in practice, if you defrost the biological material again, it often dies or loses its original function. Ice crystals are a significant cause of such so-called cryo-injuries. These crystals rupture cells, causing them to leak fluids. This is also why red fruit becomes mushy upon defrosting, as Voets explains in a recent episode of the Dutch TV show Klokhuis .
Inspiration from Arctic fish
However, nature provides valuable inspiration for a solution: species that live just below the ice in frozen lakes, such as Arctic fish. In the cold waters of Antarctica, covered with ice floes, the mercury drops to little more than a few degrees below zero. The salt in seawater lowers the freezing point to -1.9 °C.
The blood of the icefish that live here is only half as salty as the surrounding seawater, yet they do not freeze. That sparked scientists' curiosity and led to the discovery of small ice-binding proteins, known as antifreeze proteins, which are present in the blood of icefish year-round.
Nanoscale landscape of hills and valleys
Most materials do not adhere to ice, but antifreeze proteins do. They attach themselves to the surface of an ice crystal and remain there. Water molecules can no longer adhere to these occupied areas. As a result, the ice only grows in the spaces between the bound proteins. This creates an ice-water interface that, on a nanoscale, is no longer flat but curved, like a landscape with small hills and valleys. Because such a curved surface is energetically unfavorable, the further growth of ice is greatly slowed down. This video explains the process in more detail.
These proteins are extremely effective: even the smallest amounts can keep ice crystals small and allow the blood of ice fish to continue flowing. Ice-binding proteins have been discovered in numerous plants and animal species, including fish and rays, insects, bacteria, microalgae, and fleas. They use ice-binding proteins in very different ways to survive, and Voets' goal is to understand precisely how this works.
Putting bacteria to work
"In the chemical biology laboratory at TU/e, we use bacteria to produce ice-binding proteins for us. This way, we don't have to isolate them from ice fish for our research. That's not only better for the ice fish, but also useful for us, because it allows us to tinker with the protein structure very precisely in order to find out which parts are essential for the function of the proteins."
Together with colleagues at Wageningen University & Research and Washington University, they used AI to computationally design proteins that did not yet exist, with the desired properties. Using E. coli bacteria, they produce these artificial proteins in the lab. Voets and her TU/e colleagues then study how the proteins interact with ice crystals under different circumstances.
New family of artificially designed proteins
In a recent paper in PNAS , the joint team presents an entirely new family of artificially designed proteins that is more stable, more active, and more versatile than the ice-binding proteins that exist in nature, Voets explains. "Naturally occurring ice-binding proteins are generally only found in cold environments. Some of these proteins already lose their characteristic folding and thus their ability to bind ice at room temperature. The new class of proteins we developed remains stable in a much wider temperature range."
That is very useful for practical applications, stresses Voets. "Imagine that you would want to add such proteins to human organs to freeze them for storage. The fact that these proteins don't need to be kept at low temperatures to remain functional makes the handling a lot easier, as you do not need special cooling equipment or expertise."
Converging developments
According to Voets, this important breakthrough was not only the result of hard work and determination, but also of perfect timing: "Several developments are now converging", she explains. "There has been huge progress in computational methods for designing these proteins. At the same time, the world's most powerful super-resolved fluorescence microscopes are available at the ICMS Advanced Microscopy Facility (AMF) , allowing us to track individual proteins on ice for the first time. On top of that, interdisciplinary collaborations with biomedical engineers at the Institute for Complex Molecular Systems , cardiologists at Utrecht University Medical Center, and transplant surgeons at University Medical Center Groningen have been essential."
Next step toward societal impact
One of the contributing TU/e researchers is postdoc Tim Hogervorst from the Self-Organizing Soft Matter group . He discovered that the essential properties of these proteins can also be transferred to polymer-based materials, enabling scalable, cost-efficient production. In collaboration with The Gate , Voets and Hogervorst are now taking the next step toward societal impact by investigating how this discovery can be transformed into a practical, real-world product, available for others to use.
The €150.000 Proof of Concept grant Voets recently received from the European Research Council will definitely help her achieve that goal. And should open the way for the pragmatic use of her new antifreeze materials, marking a critical step toward the long-term goal of high-quality preservation of tissue and organs.
