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Two-Color Probe to Monitor a Wide Range of pH Values in Cells


  • This work was supported by the CRI project (20120000243, J.S.K.) and by the Basic Science Research Program (2012R1A1A2006259, C.K.) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology.


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High-tech pH paper: A “chameleon” pH probe composed of rhodamine (red, see scheme) and fluorescein (green) units emits at wavelengths of 580 nm and 512 nm, where the intensities show a contrary response to pH changes. Confocal microscopy of HeLa cells with this probe reveals red and green spots; the ratio of these signals can be calibrated to give the pH value of the respective organelle.