Optical Legos: Building Nanoshell Structures

Heptamers containing seven nanoshells have unique optical properties. Image courtesy of Rice University.

Scientists from four universities in the United States have created a way to use light-activated nanoshells as building blocks for 2D and 3D structures. The structures could be used in chemical sensors, nanolasers and light-absorbing metamaterials. The scientists are using the new chemical self-assembly method to build complex structures that can trap, store and bend light.

The research appears in this week’s issue of the journal Science.

“We used the method to make a seven-nanoshell structure that creates a particular type of interference pattern called a Fano resonance,” says study co-author Peter Nordlander, Professor of Physics and Astronomy at Rice University. “These resonances arise from peculiar light wave interference effects, and they occur only in man-made materials. Because these heptamers are self-assembled, they are relatively easy to make, so this could have significant commercial implications.”

Because of the unique nature of Fano resonances, the new materials can trap light, store energy and bend light in bizarre ways that no natural material can. Nordlander says the new materials are suited for making ultrasensitive biological and chemical sensors. They also could be useful in nanolasers and potentially in integrated photonic circuits that are powered by light.

The new self-assembly method developed by Capasso’s team was also used to make magnetic three-nanoshell “trimers.” The optical properties of these are described in the Science paper, which also discusses how the self-assembly method could be used to build even more complex 3D structures.

Nanoshells, the building blocks that were used in the new study, are about 20 times smaller than red blood cells. By varying the size of the glass center and the thickness of the gold shell, Halas can create nanoshells that interact with specific wavelengths of light.

“Nanoshells were already among the most versatile of all plasmonic nanoparticles, and this new self-assembly method for complex 2D and 3D structures simply adds to that,” says Halas, who has helped develop a number of biological applications for nanoshells, including diagnostic applications and a minimally invasive procedure for treating cancer.

More information on the research is available from PhysOrg.

More recent nanotech-related information can be found in our recent posts titled “Survey: Micro- and Nanotechnology Atlas of Germany” and “Molecular Robots on the Rise“.

Tags: chemical sensors, light-absorbing metamaterials, nanolasers, nanoshell, Peter Nordlander