Building Smart Nanostructures

Engineers from Duke say they have made progress building so-called "smart nanostructures," including billionths-of-a-meter-scale "nanobrushes" that can selectively and reversibly sprout from surfaces in response to changes in temperature or solvent chemistry.

In talks delivered during the American Chemical Society's annual meeting in California, researchers from the Pratt School of Engineering also told how they are using an atomic-force microscope to create reprogrammable "nanopatterns" of large, biologically based molecules that could, among other things, potentially be used to analyze the protein contents of individual cells. The molecules are reprogrammable, in that they could be activated, deactivated, and then activated again for another use. They could serve as analytical tools because they could capture and isolate select proteins from complex mixtures.

The molecular dimensions of this work--at the billionths-of-a-meter scale--"introduces the concept of scaling down chemistries to very small lengths," says Stefan Zauscher, a Duke assistant professor of mechanical engineering and materials science. He was an organizer of a society symposium called "Smart Polymers on Colloids and Surfaces." "Smart" polymers are long-chained molecules that can reversibly change their conformations as well as reversibly and selectively bind to other molecules. Besides nanobrushes, other examples of smart, large molecules include those that interact through molecular recognition, such as streptavidin and biotin, and the biologically inspired elastin-like polypeptides.

Duke engineering researchers have developed ways to pattern all these constituents so they can react at nanoscale dimensions, he says. "One reason is simply the challenge: Can we make features this small? Also, making features that small means you could get away with using very small amounts of chemicals--for example, of proteins you might want to detect."