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Engineering Phase Changes in Nanoparticle Arrays

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Introducing "reprogramming" DNA strands into an already assembled nanoparticle array triggers a transition from a "mother phase," where particles occupy the corners and center of a cube (left), to a more compact "daughter phase" (right).

Scientists at Brookhaven National Laboratory are working on the development of dynamic nanomaterials whose structure and properties can be changed on demand.

Credit: Brookhaven National Laboratory

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory are developing dynamic nanomaterials whose structure and associated properties can be switched on demand.

They describe a way to selectively rearrange the nanoparticles in three-dimensional arrays to produce different configurations, or phases, from the same nano-components. The goal is to make "materials that can transform so we can take advantage of properties that emerge with the particles' rearrangements," explains researcher Oleg Gang.

The ability to direct particle rearrangements, or phase changes, will enable the scientists to choose the desired properties, such as the material's response to light or a magnetic field, and switch them as needed. Such phase-changing materials could lead to new applications, including dynamic energy-harvesting or responsive optical materials.

Researchers started with an assembly of nanoparticles already linked in a regular array by the complementary binding of the A, T, G, and C bases on single-stranded DNA tethers, and then added reprogramming DNA strands to alter the interparticle interactions. The reprogramming DNA strands adhere to open binding sites to exert additional forces on the linked-up nanoparticles.

The team used computational modeling to calculate how different kinds of reprogramming strands would alter the interparticle interactions, and found their calculations agreed with their experimental observations.

From Brookhaven National Laboratory
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