Horseradish peroxidase-driven fluorescent labeling of nanotubes with quantum dots

Biotechniques. 2006 Mar;40(3):295-6, 298, 300-2. doi: 10.2144/000112110.


We describe the first enzyme-driven technique for fluorescent labeling of single-walled carbon nanotubes (SWNTs). The labeling was performed via enzymatic biotinylation of nanotubes in the tyramide-horseradish peroxidase (HRP) reaction. Both direct and indirect fuorescent labeling of SWNTs was achieved using either biotinyl tyramide or fluorescently tagged tyramides. Biotinylated SWNTs later reacted with streptavidin-conjugated fluorophores. Linking semiconductor nanocrystals, quantum dots (Q-dots), to the surface of nanotubes resulted in their fluorescent visualization, whereas conventional fluorophores bound to SWNTs directly or through biotin-streptavidin linkage, were completely quenched. Enzymatic biotinylation permits fluorescent visualization of carbon nanotubes, which could be useful for a number of biomedical applications. In addition, other organic molecules such as proteins, antibodies, or DNA can be conjugated to biotinylated SWNTs using this approach.

Publication types

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

MeSH terms

  • Coated Materials, Biocompatible / chemistry
  • Enzymes, Immobilized / chemistry
  • Fluorescent Dyes / chemistry*
  • Horseradish Peroxidase / chemistry*
  • Microscopy, Fluorescence / methods*
  • Nanotubes / chemistry*
  • Nanotubes / ultrastructure*
  • Quantum Dots*
  • Staining and Labeling / methods


  • Coated Materials, Biocompatible
  • Enzymes, Immobilized
  • Fluorescent Dyes
  • Horseradish Peroxidase