Imaging bacterial peptidoglycan with near-infrared fluorogenic azide probes

Proc Natl Acad Sci U S A. 2014 Apr 15;111(15):5456-61. doi: 10.1073/pnas.1322727111. Epub 2014 Mar 31.


Fluorescent probes designed for activation by bioorthogonal chemistry have enabled the visualization of biomolecules in living systems. Such activatable probes with near-infrared (NIR) emission would be ideal for in vivo imaging but have proven difficult to engineer. We present the development of NIR fluorogenic azide probes based on the Si-rhodamine scaffold that undergo a fluorescence enhancement of up to 48-fold upon reaction with terminal or strained alkynes. We used the probes for mammalian cell surface imaging and, in conjunction with a new class of cyclooctyne D-amino acids, for visualization of bacterial peptidoglycan without the need to wash away unreacted probe.

Publication types

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

MeSH terms

  • Azides
  • Fluorescent Dyes
  • Molecular Imaging / methods*
  • Molecular Probe Techniques*
  • Molecular Structure
  • Peptidoglycan / chemistry
  • Peptidoglycan / ultrastructure*


  • Azides
  • Fluorescent Dyes
  • Peptidoglycan