Jerry Bernholc
North Carolina State University, USA
Keynote: J Nanomed Nanotechnol
Carbon nanotubes are highly promising for chemical and biological sensing applications, owing to their high chemical and mechanical stabilities, high surface areas and unique electronic properties. We describe the results of extensive ab initio studies of the mechanisms of detection of small molecules: ammonia, nitrogen dioxide, glucose and ethylene and simulations of nano circuits involving a nanotube functionalized with a fragment of polymerase I enzyme. The nano circuit monitors replication of a single-stranded DNA to create the full, double-stranded DNA. Experiments show that addition of DNA bases can be monitored electrically as the polymerase moves from an �??open�?� to �??closed�?� position and back with each addition, significantly affecting the current through the nanotube. When the adding complementary bases are modified through atomic substitutions, currents change depending on the base, but not enough for sequencing. We show that at varying gate voltages specific nucleotides can be dependably distinguished from others, e.g., C and G from A and T. While the current atomic modifications are insufficient to enable full differentiation between the four bases, work in progress examines additional modifications for reliable sequencing, which could potentially be used to sequence DNA by detecting electrical signatures of the adding bases. We also show that silicon nanowires, which are easier to manufacture in quantity, can be configured to display similar sensitivity. If time permits, we will also discuss computational optimization of nanoribbon-based transistor structures for beyond-Moore�??s law computing.
Jerry Bernholc is Drexel Professor of Physics at North Carolina State University. Since 2002, he also serves as a Visiting Distinguished Scientist at Oak Ridge National Laboratories. He is a fellow of APS, AAAS and MRS and a recipient of IBM's Outstanding Innovation Award, NCSU Alumni's Outstanding Research Award, NSF's Creativity Award and Beams Award for Outstanding Research from the American Physical Society. He has received his PhD from the University of Lund, Sweden, was a Postdoctoral Fellow at IBM T J Watson Center and a Senior Physicist at Exxon Research and Engineering Company.