Chemical recognition and binding kinetics in a functionalized tunnel junction

Shuai Chang, Shuo Huang, Hao Liu, Peiming Zhang, Feng Liang, Rena Akahori, Shengqin Li, Brett Gyarfas, John Shumway, Brian Ashcroft, Jin He, Stuart Lindsay

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


4(5)-(2-mercaptoethyl)-1H-imidazole-2-carboxamide is a molecule that has multiple hydrogen bonding sites and a short flexible linker. When tethered to a pair of electrodes, it traps target molecules in a tunnel junction. Surprisingly large recognition-tunneling signals are generated for all naturally occurring DNA bases A, C, G, T and 5-methyl-cytosine. Tunnel current spikes are stochastic and broadly distributed, but characteristic enough so that individual bases can be identified as a tunneling probe is scanned over DNA oligomers. Each base yields a recognizable burst of signal, the duration of which is controlled entirely by the probe speed, down to speeds of 1nms 1, implying a maximum off-rate of 3s 1 for the recognition complex. The same measurements yield a lower bound on the on-rate of 1M 1s 1. Despite the stochastic nature of the signals, an optimized multiparameter fit allows base calling from a single signal peak with an accuracy that can exceed 80% when a single type of nucleotide is present in the junction, meaning that recognition-tunneling is capable of true single-molecule analysis. The accuracy increases to 95% when multiple spikes in a signal cluster are analyzed.

Original languageEnglish (US)
Article number235101
Issue number23
StatePublished - Jun 15 2012

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering


Dive into the research topics of 'Chemical recognition and binding kinetics in a functionalized tunnel junction'. Together they form a unique fingerprint.

Cite this