Fig. 4. (a) Two-photon Fred/Fgreen titration with various pH in ionophore-treated and CMP1-labeled HeLa cells. (b) Pseudocolored ratiometric TPM images (Fred/Fgreen) of HeLa cells stained with 2 μM CMP1. (c) Higher magnification of white boxed area in (b). (d) The estimated pH values at the region of interest (ROI) indicated by white rounds in (c). Excitation wavelength: 820 nm. Scale bars: (b) 12 and (c) 4 μm.
