TEL AVIV, Israel, May 6 (UPI) -- Until now, the process of delayed freezing has remained a mostly mystery to scientists. Delayed freezing happens when supercooled liquids are disturbed.
New research out of Tel Aviv University has illuminated the mechanics of the phenomenon, and scientists say doctors could potentially use the delayed freezing process to the advantage of patients -- freezing drugs around the targeted tissue.
Unlike a tray of water put into the freezer, which gradually turns to ice as the cooling liquid water reaches the freezing point, supercooled liquids can remain in their liquid state well below their normal freezing point.
To be effectively supercooled, liquids must be cleared of all impurities and free of nucleation sites, places where crystals can begin to form and initiate the substance's restructuring (freezing). Supercooling happens because the freezing process (the formation of crystalline structures) requires nucleation sites to get started.
A liquid can begin forming crystalline structures on its own, but it must be cooled to a much lower temperature than normal. When nucleation sites are introduced (a foreign object, for example) to supercooled liquids, freezing happens rapidly.
Until recently, researchers didn't entirely understand this phase transition -- from metastable supercooled liquid to stable frozen solid. To most scientists, the rapid freezing of supercooled liquids seemed spontaneous and nearly unpredictable. But the latest research suggests these mechanics can be manipulated, and that supercooled liquids aren't quite as sensitive to microscopic fluctuations.
"We discovered in our study that it is possible to control the process and harness the advantages of the fluid/not-fluid transition to design a precise and effective nanoscale drug encapsulating system," Dr. Roy Beck, a physicist at Tel Aviv, explained in a press release.
Researchers studied the crystalizing process of supercooled gel capsules using advanced X-ray imaging. They were able to produce tiny packets of supercooled liquid that remained stable for 10 hours before rapidly freezing.
"What was amazing was our ability to reproduce the results over and over again without any complicated techniques," said Beck. "We showed that the delayed crystallization was not sensitive to minor imperfection or external perturbation. Moreover, we found multiple alternative ways to 'tweak the clock' and start the crystallization process."
Now, researchers are trying to design the proper encapsulation, a drug delivery device that will deliver the supercooled drugs at the right time and location, allowing them to freeze on-site.
"The challenge now is to find the right drugs to exploit our insights for the medical benefit of patients," said Beck.
The new research was recently published in the journal Scientific Reports.