Resolution of lysosomes in living cells with a ratiometric molecular pH-meter

Talanta. 2013 Sep 30;114:254-60. doi: 10.1016/j.talanta.2013.05.036. Epub 2013 Jun 6.


Intracellular acidic vesicles, constituted mostly by lysosomes, mediated a variety of biological events ranging from endocytosis, apoptosis, to cancer metastasis, etc. A chimeric molecular pH-meter (Lyso-DR), comprised of a dansyl fluorophore and proton activatable rhodamine-lactam, was prepared for ratiometric reporting of intralysosomal acidity. Exclusively confined in lysosomes, Lyso-DR exhibited pH dependent dual fluorescence emission bands which enable resolution of individual lysosomes in terms of acidity and quantitation of the overall intracellular lysosomal acidity, e.g. the lysosomal pH of HeLa cells is around pH 5.0 whereas that of L929 cells is around pH 6.2. Lyso-DR effectively differentiated the lysosomal pH changes of cells undergoing apoptosis vs necrosis, suggesting its utility in investigations on lysosome involved biomedical processes.

Keywords: Apoptosis; Lysosomal acidity; Molecular pH-meter; Ratiometric imaging.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Cell Line
  • Fluorescent Dyes / chemistry
  • HeLa Cells
  • Humans
  • Hydrogen-Ion Concentration
  • Lysosomes / chemistry*
  • Mice
  • Necrosis
  • Rhodamines / chemistry


  • Fluorescent Dyes
  • Rhodamines