A ratiometric pH reporter for imaging protein-dye conjugates in living cells

The application of ratiometric probes that absorb ultraviolet (UV) excitation at a fixed wavelength and emit at two different fluorescence wavelengths in a pH dependent manner is demonstrated. The newly designed energy transfer approach to pH probe facilitate observation of processes within the cell and have significant potential for modifications with other pH sensitive donor to give a spectrum of probes with systematically varied pH response transitions.