Professors Dong June Ahn, Seungwoo Lee and Dong-Kwon Lim developed a gold nanoparticle-based antifreeze nanomaterial that mimics antifreeze proteins.

The research findings are published in the Journal of the American Chemical Society.

The team led by Professors Dong June Ahn, Seungwoo Lee and Dong-Kwon Lim, KU-KIST Graduate School of Converging Science and Technology, developed a new antifreeze nanomaterial that mimics the antifreeze proteins (AFP) of organisms living in extremely cold regions. The research findings were published on October 16 in the Journal of the American Chemical Society (IF: 14.695).

* Authors: Seungwoo Lee/Dong June Ahn (corresponding authors, Korea University), Dong-Kwon Lim (co-author, Korea University), Jaewon Lee/Sang Yup Lee (co-first authors, Korea University)

* Research title: Antifreezing Gold Colloids

For living organisms, an ice-freezing environment can be fatal. When water molecules begin to freeze, sharp ice crystals are formed within an organism that can destroy its cells. As extracellular water freezes, the concentration of extracellular substances increases, causing osmosis to dehydrate an organism’s cells. Similar to cabbage being pickled in salted water, the cells will shrivel and eventually die. To protect themselves from such ice attacks, organisms in extremely cold regions have evolved to produce antifreeze protein (AFP)—an agent that prevents the organism from freezing. This prevents the growth of ice crystals in the body at sub-zero temperatures and prevents cell damage, allowing such organisms to survive in extreme environments.

Although cryopreservation has been used for several decades to preserve cells in extremely low temperatures for medical and research applications, this method could only be employed on limited species due to the damage the toxic chemical antifreeze agent causes to cells. As a result, AFP has been investigated as a non-toxic antifreeze to replace harmful chemical antifreeze agents. However, AFPs have not been widely used until now due to their instability, difficulty to mass produce and high cost.

A team led by Professors Dong June Ahn, Seungwoo Lee and Dong-Kwon Lim, KU-KIST Graduate School of Converging Science and Technology, overcame the above limitations by developing freeze-control nanomaterials based on gold nanoparticles that simulate the structural and chemical properties of AFPs. The team arranged oligopeptides that mimic cryoprotectant proteins on the surface of chemically mass-produced gold nanoparticles to create a nanomaterial that can adhere to ice crystals. The research findings proved that this material effectively inhibits the growth and recrystallization of ice crystals. In particular, the team succeeded in developing a high-efficiency antifreeze agent that is effective in small amounts; the material has functions similar to AFPs, even at a concentration that is 100 times lower than that of AFPs.

In addition, the team tested the efficiency of freeze-control inhabitation depending on the shape of the gold nanomaterials and the contact point between the freeze-control material and the ice crystal. It was proved that, compared to point-like contacts, facet contacts are better at maximizing the interaction between ice and freeze-control materials and that they increased freeze control performance. Since this issue has long been unsolvable in the field of AFP research, the findings are expected to offer a new paradigm for the study of AFPs and freeze-control materials that mimic AFPs.

It is anticipated that the research findings will be applied to the basic technology for economically producing non-toxic and highly-efficient antifreeze materials, which will not only influence cell therapy studies in the medical and pharmaceutical industries, but also have great impact on a wide range of other fields, including agriculture, livestock, fisheries and food industries.

This work was supported by the Future Material Discovery Project (The Water-Ice Interface Augmentation Center led by Dong June Ahn).

[Figure 1] A schematic diagram showing the fundamentals of freeze-control nanomaterials based on gold nanoparticles. The growth of ice crystals is inhibited by arranging oligopeptides on the surface of a gold nanoparticle that mimics an AFP.

[Figure 2] Comparison of freeze-control performance. For distilled water (first row) and bare gold nanoparticles (second row), ice crystals grow larger over time, while the growth of ice crystals is inhibited by oligopeptide-surfaced gold nanoparticles (third row).