Using catalysts to stamp nanopatterns w...( DURHAM N.C. Using enzymes from E. c...)

DURHAM, N.C. Using enzymes from E. coli bacteria, Duke University chemists and engineers have introduced a hundred-fold improvement in the precision of features imprinted to create microdevices such as labs-on-a-chip.

Their inkless microcontact printing technique can imprint details measuring close to 1 nanometer, or billionths of a meter, the Duke team reported in the Sept. 24, 2007 issue of the Journal of Organic Chemistry.

"This has a lot of potential, because we don't have the resolution issue," said Robert Clark, a professor of mechanical engineering and materials science and dean at Dukes Pratt School of Engineering. The really important part is that with a biological catalyst theres no ink involved, added Duke chemistry professor Eric Toone.

Clark, Toone and three graduate students authored the report on their study, which was funded by the National Science Foundation (NSF).

In traditional microcontact printing -- also called soft lithography or microstamping -- an elastic stamps end is cast from a mold created via photolithograpy a technique used to generate microscopic patterns with light. Those patterns are then transferred to a surface by employing various biomolecules as inks, rather like a rubber stamp.

Microcontact printing was first reported by Ralph Nuzzo and Dave Allara at Pennsylvania State University, and developed extensively in the laboratory of George Whitesides at Harvard.

A shortcoming of traditional microcontact printing is that pattern transfer relies on the diffusion of ink from the stamp to the surface. This same diffusion spreads out beyond the limits of the pattern as the stamp touches the surface, degrading resolution and blurring the feature edges, Clark and Toone said.

Because of this mini-blurring, the practical limit to defect-free patterning is in excess of 100 nanometers, said the report, whose first author, Phillip Snyder, is a former Toone graduate student
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