Multicolor live-cell chemical imaging by isotopically edited alkyne vibrational palette

J Am Chem Soc. 2014 Jun 4;136(22):8027-33. doi: 10.1021/ja502706q. Epub 2014 May 21.

Abstract

Vibrational imaging such as Raman microscopy is a powerful technique for visualizing a variety of molecules in live cells and tissues with chemical contrast. Going beyond the conventional label-free modality, recent advance of coupling alkyne vibrational tags with stimulated Raman scattering microscopy paves the way for imaging a wide spectrum of alkyne-labeled small biomolecules with superb sensitivity, specificity, resolution, biocompatibility, and minimal perturbation. Unfortunately, the currently available alkyne tag only processes a single vibrational "color", which prohibits multiplex chemical imaging of small molecules in a way that is being routinely practiced in fluorescence microscopy. Herein we develop a three-color vibrational palette of alkyne tags using a (13)C-based isotopic editing strategy. We first synthesized (13)C isotopologues of EdU, a DNA metabolic reporter, by using the newly developed alkyne cross-metathesis reaction. Consistent with theoretical predictions, the mono-(13)C ((13)C≡(12)C) and bis-(13)C ((13)C≡(13)C) labeled alkyne isotopologues display Raman peaks that are red-shifted and spectrally resolved from the originally unlabeled ((12)C≡(12)C) alkynyl probe. We further demonstrated three-color chemical imaging of nascent DNA, RNA, and newly uptaken fatty-acid in live mammalian cells with a simultaneous treatment of three different isotopically edited alkynyl metabolic reporters. The alkyne vibrational palette presented here thus opens up multicolor imaging of small biomolecules, enlightening a new dimension of chemical imaging.

Publication types

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

MeSH terms

  • Alkynes / chemistry*
  • Color
  • DNA / chemistry
  • DNA / metabolism
  • DNA / ultrastructure
  • Fatty Acids / chemistry
  • Fatty Acids / metabolism
  • HeLa Cells
  • Humans
  • Indicators and Reagents
  • Microscopy / methods*
  • RNA / chemistry
  • RNA / metabolism
  • RNA / ultrastructure
  • Scattering, Radiation
  • Spectrum Analysis, Raman
  • Vibration

Substances

  • Alkynes
  • Fatty Acids
  • Indicators and Reagents
  • RNA
  • DNA