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NUANCE: Nanoscale Characterization Experimental Center

NUANCE Enables Work on Superlattices

Research enabled by NUANCE was recently published by Science. In “Building Superlattices from Individual Nanoparticles via Template-Confined DNA-mediated Assembly” researchers Chad A. Mirkin, Vinayak P. Dravid and Koray Aydin’s findings reveal how to make new classes optical materials and devices that could lead to light bending and cloaking devices.

Qing-Yuan Lin, lead author of the study used NUANCE’s FEI Quanta 650F and Hitachi S-4800-II and SU-8030 microscopes during this work allowing researchers to ‘see’ the structures.

Calling it a true example of “man over matter” researches said the made structures don't exist in nature. In summary their findings describe how nanoparticles can now be organized in two and three dimensions using the same lithography methods used to make computer chips. In it they define landing pads for nanoparticle components modified with one sequence of DNA.

The particles are modified with complementary DNA. These pads are buried in three-dimensional holes in a polymer resist to be grown vertically. By altering particles with complementary DNA, particle stacks with tremendous positional control can be built over a large area. The particles can be different sizes and shapes -- spheres, cubes, discs -- building periodic lattices from optically active particles made of any material that can be modified with DNA such as gold or silver, with nanoscale precision.

Dravid said the discovery “creates a challenge to the scientific community to explore how they can be translated into useful technologies. This is a laying down of the gauntlet to the physics and chemistry communities to explore and create a whole new playground of highly functional optical materials.”

Lin explained that he used Quanta for electron beam lithography adding that “it’s like using a pen to draw patterns on a piece of paper” but that the ‘pen’ is made of an electron beam to precisely draw patterns designed on a flat surface. The pattern became a template for the construction of the optically active structures reported in the study.
Superlattice Image
NUANCE founding director, Professor Dravid assisted in designing the nanopatterning and lithography strategy and the associated characterization of the new exotic structures. NUANCE center houses the advanced patterning, lithography and characterization used in the DNA-programmed structures. Qing-Yuan Lin, Jarad A. Mason and Zhongyang Li are first authors of the study. Chad Mirkin and Vinayak P. Dravid and Koray Aydin are professors at Northwestern’s McCormick School of Engineering and are co-corresponding authors.