1-Naphthol as an excited state proton transfer fluorescent probe for erythrocyte membranes

The microenvironmental dependence of excited state prototropism of 1-naphthol and the corresponding changes in its fluorescence emission is utilized to monitor the acyl chain melting phase transition behavior of liposome membrane made from human erythrocyte lipids. A sharp increase in the ratio of neutral/anionic form fluorescence intensity is noticed at the phase transition temperature (19 degrees C). This provides a convenient method for obtaining phase transition temperature in lipid membranes. The membrane modifying effect of cholesterol on the erythrocyte liposome is successfully sensed by 1-naphthol fluorescence.