Fluorescence spectroscopy of planar black lipid membranes Probe adsorption and quantum yield determination

A technique is described for the examination of fluorescence in planar black lipid membranes. Special attention has been devoted to the elimination of light scattered from the border regions of the membrane and from the numerous small lenses of hydrocarbon solvent which can form in certain types of black film. Fluorescence spectra of 1-anilino-8-naphthalene sulphonate (ANS) are reported for phospholipid and monoglyceride membranes. The adsorption of the fluorescent probe has been measured by a thermodynamic method and the quantum yield of the probe in the membrane has been determined. Both the emission spectrum and the quantum yield of ANS in black films agree well with the respective data obtained from measurements on sonicated aqueous dispersions of the lipid.