Making Contact (IMAGE) Arizona State University Caption A gold probe, outfitted with a dangling nucleotide approaches its complementary base, protruding upward from a monolayer. A set point current is established for the tunnel junction as the bases self-assemble. As the electrode is slowly withdrawn, the drop in tunneling current is recorded. Examining the curve of current vs. distance allows the identification of A-T base pairs, which may be distinguished from more strongly bonded C-G pairs -- cemented by 3 rather than 2 hydrogen bonds. Credit Biodesign Institute at ASU Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.