Nanoscale superclusters that mirror living systems

August 25, 2011

Basic atomic forces can enable nanoparticles to assemble into superclusters that are uniform in size and share attributes with viruses (credit: T.D.Nguyen, Glotzer Group, University of Michigan)

University of Michigan researchers have discovered that if you start with small nanoscale building blocks that are varied enough in size, the atomic electrostatic repulsion force and van der Waals attraction force will balance each other and limit the growth of the clusters. This equilibrium enables the formation of clusters that are uniform in size — an attribute that’s important for many nanotech applications but hard to accomplish, the researchers say.

The same type of forces are at work bringing the building blocks of viruses together, and the inorganic supercluster structures in this research are in many ways similar to viruses.

(Credit: T.D.Nguyen, Glotzer Group, University of Michigan)

The inorganic superclusters — technically called “supraparticles” — that the researchers created out of red, powdery cadmium selenide are not artificial viruses. But they do share many attributes with viruses, including size, shape, core-shell structure and the abilities to both assemble and dissemble.

“Having these functionalities in totally inorganic system is quite remarkable,” chemical engineering professor Nicholas Kotov said. “There is the potential to combine them with the beneficial properties of inorganic materials such as environmental resilience, light adsorption and electrical conductivity.”

Kotov is currently working on “breeding” these supraparticles to produce synthetic fuels from carbon dioxide. The work also has applications in drug delivery and solar cell research and it could dramatically reduce the cost of manufacturing large quantities of supraparticles.

“By replicating the self-assembly processes that allow living organisms to grow and heal, we can simplify the production of many useful nanostructured systems from semiconductors and metals so much so that they can be made in any high school laboratory,” Kotov said.

Ref.: Yunsheng Xia et al., Self-assembly of self-limiting monodisperse supraparticles from polydisperse nanoparticles, Nature Nanotechnology (2011) doi:10.1038/nnano.2011.121