Optical and electrical detection of single-molecule translocation through carbon nanotubes

ACS Nano. 2013 Jan 22;7(1):689-94. doi: 10.1021/nn3050598. Epub 2012 Dec 24.


Ion current through a single-walled carbon nanotube (SWCNT) was monitored at the same time as fluorescence was recorded from charged dye molecules translocating through the SWCNT. Fluorescence bursts generally follow ion current peaks with a delay time consistent with diffusion from the end of the SWCNT to the fluorescence collection point. The fluorescence amplitude distribution of the bursts is consistent with single-molecule signals. Thus each peak in the ion current flowing through the SWCNT is associated with the translocation of a single molecule. Ion current peaks (as opposed to blockades) were produced by both positively (Rhodamine 6G) and negatively (Alexa 546) charged molecules, showing that the charge filtering responsible for the current bursts is caused by the molecules themselves.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Conductometry / methods*
  • Diffusion
  • Materials Testing
  • Molecular Probe Techniques*
  • Nanotubes, Carbon / chemistry*
  • Nanotubes, Carbon / ultrastructure*
  • Particle Size
  • Rhodamines / analysis*
  • Rhodamines / chemistry*
  • Spectrometry, Fluorescence / methods*


  • Nanotubes, Carbon
  • Rhodamines
  • rhodamine 6G