Coumarin-based fluorescent biosensor with large linear range for ratiometric measurement of intracellular pH

Bioorg Chem. 2020 Dec:105:104372. doi: 10.1016/j.bioorg.2020.104372. Epub 2020 Oct 12.


Intracellular pH is a critical parameter involved in cell machinery, and its dysregulation can either cause or signal pathologic states. Currently described fluorescent pH probes are based on single acid-base equilibria, and for this reason are intrinsically unable to capture the wide range of cell pH, usually spanning over more than four units. Here we describe a fluorescent pH biosensor based on a conjugated coumarin-triazine scaffold that is excitable in the visible range, shows pseudo-linear ratiometric response over more than 6 pH units with a single fluorogenic unit, and allows imaging of the whole endo-lysosomal pH landscape of living cells with a single acquisition. The probe can discriminate, on the basis of intracellular acidity, between physiologic and tumor cells, being potentially suitable in perspective as diagnostic tool.

Keywords: Coumarin; Fluorescent probes; Ratiometric imaging; Triazines; pH sensing.

MeSH terms

  • Biosensing Techniques*
  • Cells, Cultured
  • Coumarins / chemical synthesis
  • Coumarins / chemistry*
  • Fluorescent Dyes / chemical synthesis
  • Fluorescent Dyes / chemistry*
  • Humans
  • Hydrogen-Ion Concentration
  • Optical Imaging
  • Spectrometry, Fluorescence
  • Triazines / chemical synthesis
  • Triazines / chemistry*


  • Coumarins
  • Fluorescent Dyes
  • Triazines
  • coumarin