Ice formation can damage biological samples, tissues and materials during freezing and thawing. In nature, specialised molecules known as ice‑binding proteins prevent ice crystals from growing too large, helping organisms survive in extreme cold.
Scientists have long tried to replicate this behaviour using synthetic materials, but most designs have focused on how molecules interact with ice at their surface.
In a study published in Chemical Science , the team – led by Professor Matthew Gibson – have shown for the first time that the internal structure of polymer nanoparticles, rather than their outer surface, plays a key role in controlling ice growth. This was a collaboration with Professor Steve Armes FRS at Sheffield Univeristy.
Looking inside the particle
The team created a library of polymer nanoparticles using a scalable technique known as polymerisation‑induced self‑assembly. These particles consist of a water‑exposed outer layer and a hidden inner core.
Surprisingly, the researchers found that changing the chemistry of the inner core dramatically altered how effectively the particles inhibited ice recrystallisation – the process by which ice crystals grow larger over time.
Particles with "soft" cores showed significantly higher activity, strongly suppressing ice growth, while those with more rigid cores were less effective.
Even more strikingly, chemically locking the core structure removed this activity entirely.
"This work shows that we can tune ice‑controlling properties by engineering the inside of nanoparticles, rather than just their surface, meaning we can fine-tune performance, without impacting how the particle interacts with its environment.," Matthew Gibson, Chair in Sustainable Biomaterials
Applications from medicine to materials
Materials that control ice growth are important in a wide range of applications, from preserving cells and tissues to improving the texture of frozen foods and developing anti‑icing coatings.
By providing a new way to design these materials, the research opens up opportunities to develop more effective, scalable and cost‑efficient alternatives to natural antifreeze proteins.
The work also establishes a broader framework for designing functional nanoparticles, showing that internal structure can be as important as surface chemistry in determining performance.
