q&more
My watch list
my.chemie.de  
Login  

News

Water that never freezes

Peter Rüegg / ETH Zürich

Three-dimensional model of the novel lipid mesophase: This cubic motif is repeated regularly in the material.

12-Apr-2019: Can water reach minus 263 degrees Celsius without turning into ice? Yes it can, say researchers from ETH Zurich and the University of Zurich, if it is confined in nanometre-scale lipid channels.

Making ice cubes is a simple process: you take a plastic ice-cube tray like you’d find in most households, fill it with water and put it in the freezer. Before long, the water crystallises and turns to ice.

If you were to analyse the structure of ice crystals, you’d see that the water molecules are arranged in regular 3-dimensional lattice structures. In water, by contrast, the molecules are unorganised, which is the reason that water flows.

Glassy water

Led by Professors Raffaele Mezzenga and Ehud Landau, a group of physicists and chemists from ETH Zurich and the University of Zurich have now identified an unusual way to prevent water from forming ice crystals, so even at extreme sub-zero temperatures it retains the amorphous characteristics of a liquid.

In a first step, the researchers designed and synthesised a new class of lipids (fat molecules) to create a new form of “soft” biological matter known as a lipidic mesophase. In this material, the lipids spontaneously self-assemble and aggregate to form membranes, behaving in a similar way as natural fat molecules. These membranes then adopt a uniform arrangement to form a network of connected channels that measure less than one nanometer in diameter. Temperature and water content, as well as the novel structure of the designed lipid molecules determine the structure that the lipidic mesophase takes.

No space for water crystals

What’s so special about this structure is that – unlike in an ice-cube tray – there is no room in the narrow channels for water to form ice crystals, so it remains disordered even at extreme sub-zero temperatures. The lipids don’t freeze either.

Using liquid helium, the researchers were able to cool a lipidic mesophase consisting of a chemically modified monoacylglycerol to a temperature as low as minus 263 degrees Celsius, which is a mere 10 degrees above the absolute zero temperature, and still no ice crystals formed. At this temperature, the water became “glassy”, as the researchers were able to demonstrate and confirm in a simulation. Their study of this unusual behaviour of water when confined within a lipidic mesophase was recently published in the journal Nature Nanotechnology.

“The key factor is the ratio of lipids to water,” explains Professor Raffaele Mezzenga from the Laboratory of Food & Soft Materials at ETH Zurich. Accordingly, it is the water content in the mixture that determines the temperatures at which the geometry of the mesophase changes. If, for example, the mixture contains 12 percent water by volume, the structure of the mesophase will transition at about minus 15 degrees Celsius from a cubic labyrinth to a lamellar structure.

Natural antifreeze for bacteria

“What makes developing these lipids so tricky is their synthesis and purification,” says Ehud Landau, Professor of Chemistry at the University of Zurich. He explains that this is because lipid molecules have two parts; one that is hydrophobic (repels water) and one that is hydrophilic (attracts water). “This makes them extremely difficult to work with,” he says.

The soft biomaterial formed from the lipid membranes and water has a complex structure that minimises the water’s contact with the hydrophobic parts and maximises its interface with the hydrophilic parts.

The researchers modelled the new class of lipids on membranes of certain bacteria. These bacteria also produce a special class of self-assembling lipids that can naturally confine water in their interior, enabling the microorganisms to survive in very cold environments.

“The novelty of our lipids is the introduction of highly strained three-membered rings into specific positions within the hydrophobic parts of the molecules”, says Landau. “These enable the necessary curvature to produce such tiny water channels and prevent lipids to crystallize.”

Soft matter for research

These new lipidic mesophases will serve primarily as a tool for other researchers. They can be utilised to non-destructively isolate, preserve and study large biomolecules in a membrane-mimicking environment, for instance by using cryogenic electron microscopy. Biologists are increasingly turning to this method to determine the structures and functions of large biomolecules such as proteins or large molecular complexes.

“In the normal freezing process, when ice crystals form they usually damage and destroy membranes and crucial large biomolecules, which prevents us from determining their structure and function when they interact with lipid membranes,” Mezzenga says.

But not with the new mesophase, which is non-destructive and preserves such molecules in their original state and in presence of the other key building block of life, that is the lipids. “Our research is paving the way for future projects to determine how proteins might be preserved in their original form and interact with lipid membranes at very low temperatures,” says the ETH professor.

This new class of soft matter could also be employed in potential applications wherever water must be prevented from freezing. “But our work wasn’t aimed at exotic applications,” Mezzenga says: “Our main focus was to give researchers a new tool to facilitate the study of molecular structures at low temperature without ice-interfering crystals, and ultimately to understand how two main components of life, i.e. water and lipids, interact under extreme conditions of temperature and geometrical confinement” he adds.

Original publication:
Salvati Manni L, Assenza S, Duss M, Vallooran JJ, Juranyi F, Jurt S, Zerbe O, Landau EM, Mezzenga R.; "Soft biomimetic nanoconfinement promotes amorphous water over ice"; Nature Nanotechnology; Published: 08.April 2019.

Facts, background information, dossiers

More about ETH Zürich

  • News

    When sand behaves like oil

    Sand, coffee grounds and rice behave very differently than water or oil, but under certain conditions they will suddenly exhibit astonishing similarities. Scientists have found a way to better understand the behaviour of granular materials. Sand, rice and coffee are all examples of granular ... more

    Fleming’s method in miniature

    Scientists in the Department of Biosystems Science and Engineering at ETH Zurich in Basel have developed a method with which they can quickly test a very large number of molecules for antibiotic effect. With it, they have already successfully discovered new antibiotic candidates produced by ... more

    Bacteria reveal strong individuality when navigating a maze

    Researchers from ETH Zurich demonstrate that genetically identical cells exhibit differing responses in their motility towards chemical attractants. Average values hide the full picture when it comes to describing the behaviour of bacteria. Although they are considered the simplest of all l ... more

  • q&more articles

    Analysis in picoliter volumes

    Reducing time, costs and human resources: many basic as well as applied analytical and diagnostic challenges can be performed on lab-on-a-chip systems. They enable sample quantities to be reduced, work steps to be automated and completed in parallel, and are ideal for combination with highl ... more

    Investment for the Future

    This is a very particular concern and at the same time the demand placed annually on Dr. Irmgard Werner, who, as a lecturer at the ETH Zurich, supports around 65 pharmacy students in the 5th semester practical training in “pharmaceutical analysis”. With joy and enthusiasm for her subject sh ... more

  • Authors

    Prof. Dr. Petra S. Dittrich

    Petra Dittrich is an Associate Professor in the Department of Biosystems Science and Engineering at ETH Zurich (Switzerland). She studied chemistry at Bielefeld University and the University of Salamanca (Spain). After completing her doctoral studies at the Max Planck Institute for Biophysi ... more

    Dr. Felix Kurth

    Felix Kurth studied bioengineering at the Technical University Dortmund (Germany) and at the Royal Institute of Technology in Stockholm (Sweden). During his PhD studies at ETH Zurich (Switzerland), which he completed in 2015, he developed lab-on-a-chip systems and methods for quantifying me ... more

    Lucas Armbrecht

    Lucas Armbrecht studied microsystems technology at the University of Freiburg (Breisgau, Germany). During his master’s, he focused on sensors & actuators and lab-on-a-chip systems. Since June 2015, he is PhD student in the Bioanalytics Group at ETH Zurich (Switzerland). In his doctoral stud ... more

More about Universität Zürich

  • News

    Simple and Fast Method for Radiolabelling Antibodies against Breast Cancer

    Radioactive antibodies that target cancer cells are used for medical diagnostics with PET imaging or for targeted radioimmunotherapy. Researchers from the University of Zurich have created a new method for radiolabelling antibodies using UV light. In less than 15 minutes, the proteins are r ... more

    Precise Decoding of Breast Cancer Cells Creates New Option for Treatment

    Researchers at the University of Zurich and from IBM Research have investigated the varying composition of cancer and immune cells in over one hundred breast tumors. They've found that aggressive tumors are often dominated by a single type of tumor cell. If certain immune cells are present ... more

    Bat Influenza Viruses Could Infect Humans

    Bats don’t only carry the deadly Ebola virus, but are also a reservoir for a new type of influenza virus. These newly discovered flu viruses could potentially also attack the cells of humans and livestock, researchers at the University of Zurich have now shown. Seasonal outbreaks of the flu ... more

  • q&more articles

    From the reveller to the lark

    Because of their genes, some people come into the world either as a lark (early riser) or a night-owl (late sleeper). In addition, however, even in normal people, such ”chronotype“ changes with age. Starting at puberty they develop into revellers. At the age of 20 a change occurs and the ... more

  • Authors

    Dr. Steven A. Brown

    Steven B. Brown studied biochemistry at Harvard College, Cambridge, Massachusetts, USA. In 1997 he received his doctorate in the Department of Biological Chemistry and Molecular Pharmacology, Harvard University, Cambridge, Massachusetts, USA. From 1998 – 2005 he was a postdoctoral fellow at ... more

q&more – the networking platform for quality excellence in lab and process

The q&more concept is to increase the visibility of recent research and innovative solutions, and support the exchange of knowledge. In the broad spectrum of subjects covered, the focus is on achieving maximum quality in highly innovative sectors. As a modern knowledge platform, q&more offers market participants one-of-a-kind networking opportunities. Cutting-edge research is presented by authors of international repute. Attractively presented in a high-quality context, and published in German and English, the original articles introduce new concepts and highlight unconventional solution strategies.

> more about q&more

q&more is supported by:

 

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE