(411b) Controlled Tethering and Stretching of DNA Molecules in Shear Flow for Organic Molecule Electronics

DNA-organic molecule-DNA (DoD) supramolecules have been recently explored as promising architectures for creating single-molecule electronic devices. With DNA segments being stretched and further metallized, reliable electrical contact can be made to single organic molecules of interest. One critical step in the process is controlled tethering and stretching of DNA molecules. In this work, we have developed reproducible surface chemistry for tethering DNA at tunable density and flow processing for controlled DNA stretching and alignment. Enzymatic cleavage of λ-phage DNA has been used to create a series of tethered DNA chains of various lengths and the effect of shear rates on flow/extension behavior of this series has been investigated with the aid of microfluidics and single molecule fluorescence microscopy. Flow dynamics of different length DNA molecules is further compared to Brownian Dynamic simulations of the Kratky-Porod chain through lengths as small as 4 microns, which matches the length of DoD complexes (1-4 μm) that can be feasibly synthesized. Furthermore, we extend our flow dynamics studies to demonstrate the controlled stretching and double tethering of thiol functionalized DNA molecules (10 kbp) between pre-defined gold electrodes. Subsequent metallization of the DNA scaffolds could eventually lead to reliable and reproducible metal contacts to single organic semiconducting molecules. This represents an important step towards single-molecule electronics, enabling efficient fabrication of nanoelectronic devices for large-scale screening of organic semiconductors on a single molecule scale.