| Popis: |
Lipophilic xanthene dyes are promising fluorescent indicators of pH at the surfaces of living cells. For this purpose, we have prepared N -dichlorofluoresceinyl-andN-fluoresceinyl-oleylamine and characterized the effects of pH on fluorescence in phospholipid vesicles, using N -oleoyl-aminorhodamine B as a pH-independent standard. Fluorescence was measured at two emission wavelengths during excitation at a single wavelength, and the ratio of the intensities was calculated. The emission ratios were fitted to the Henderson-Hasselbalch equation to give the experimentally observed p K obs . Both N -dichlorofluoresceinyl-andN-fluoresceinyl-oleylamine were sensitive indicators of pH with p K obs values of 5.2 and 6.8, respectively, and they should be applicable to the measurement of interfacial pH values. |
