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DNA gives colloidal crystals shape-shifting and memory abilities

October 17, 2022

Northwestern University researchers have uncovered a previously unknown property of colloidal crystals, highly ordered three-dimensional arrays of nanoparticles.

The team engineered colloidal crystals with complementary strands of DNA and found that dehydration crumpled the crystals, breaking down the DNA hydrogen bonds. But when researchers added water, the crystals bounced back to their original state within seconds.

The new study describes the shape memory that occurs after changes to a colloidal crystal’s structure and that is not accessible in other types of crystals. In response to external stimuli, reversible structural changes in these new materials could lead to associated dynamic functional changes that make them useful in chemical and biological sensing, optics and soft robotics.

“The deformed crystal has completely different properties when it’s broken down,” said Northwestern’s Chad A. Mirkin, who led the study. “But DNA retraces its steps. Imagine if a house was destroyed by a hurricane, but then that every nail and board returned to their original places to reform the house after the storm passed. That’s essentially equivalent to what is happening here with these crystals at the nanoscale.”

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