Thursday, 5 October 2006 - 1:40 PM
North Ballroom (Binghamton Regency Hotel and Conference Center)
62

Auto-Orientation and Manipulation of G-wire DNA Networks

James Vesenka, University of New England, Biddeford, ME

Scanning probe microscopy was used to examine quadruplex DNA networks, a.k.a. “G-wires”, after adsorption onto mica. The angles the G-wires made with the fast scan direction were measured. The angle-frequency information was compared with the underlying lattice structure of the mica substrate. The G-wires appear to have a preferential orientation at 60 degree intervals after thorough rinsing and slow drying upon the surface of freshly cleaved mica. Evidence from AFM imaging suggests the G-wires adsorb onto the mica surface in single strands or in pairs as adjacent strands collapse upon drying. This orientation could be quantitatively characterized by a correlation coefficient. A model is proposed to explain this auto-orientation affect due to alignment of the G-wires' phosphate backbone and the underlying mica lattice. Pairs of adjacent, parallel phosphate groups of the G-wires (0.95 nm apart) appear to align with the next nearest neighbor potassium vacancy sites of mica (0.90 nm apart). A different behavior is not observed in solution suggesting subtle differences between “dried” and solution forms of G-wire DNA. Upon appropriate sample preparation the G-wire DNA can make continuous, highly oriented DNA networks on a variety of types of mica substrates. To characterize the electrical properties of G-wire DNA networks micro-fabrication processes were used to construct two, three, and four point probe silicon masks with 20 um gaps. These masks were used to integrate 15-nm thick gold contacts into the G-wire DNA networks. Under dehydrated conditions the G-wire DNA acts like an electrical insulator.


Web Page: faculty.une.edu/cas/jvesenka/researchpubs/index.htm

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