Laurdan and Prodan as polarity sensitive fluorescence membrane probes

T. PARASASSI; EWA K. KRASNOWSKA; LUIS BAGATOLLI; E. GRATTON

JOURNAL OF FLUORESCENCE

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 1998 vol. 8 p. 365 - 365

1053-0509

he steady-state and dynamic fluorescence spectral properties of 2-dimethylamino-6-lauroylnaphthalene (LAURDAN) and several other naphthalene derivatives are summarized to illustrate their sensitivity to the polarity of the environment. Results obtained both in solvents of different polarity and in phospholipid vesicles in two phase states are presented. The emission red shift observed in polar solvents and in the phospholipid liquid?crystalline phase is explained on the basis of dipolar relaxation of solvent molecules surrounding the fluorescent naphthalene moiety of these probes. In phospholipid environments, experimental evidence is shown that excludes the intramolecular relative reorientation of the dimethylamino and carbonyl groups in the naphthalene and the reorientation of the entire fluorescent moiety. The solvent dipolar relaxation observed for LAURDAN and PRODAN in phospholipid bilayers has been attributed to a small number of water molecules present at the membrane interface