Figure 1: Infinite dilution of the fluorescent lipids.

Intrinsic fluorescence of NBD-DOPE, i.e. total fluorescence divided by the quantity of dyes, was measured for various fractions of fluorescent lipids (NBD-DOPE and Rho-DOPE being both equal). The circles are data points with only fluorescent liposomes at 18 mM lipids. Triangles were obtained from various experiments in which there was a mixture of fluorescent and non-fluorescent liposomes at ratios varying from 1:2 to 1:10; the total lipid concentration also being 18 mM. As fluorescent lipid fractions decrease, FRET between NBD and Rhodamine is reduced. The plateau, corresponding to the absence of FRET, i.e. infinite dilution, is reached for fluorescent lipids fraction bellow or equal to 0.01%, i.e. for ~1 fluorescent lipid per liposome or less. 1 was set as the average of the data points below 0.01% from the purely fluorescent lipids. Error bars are the minimum and maximum values from 4 different wells (often smaller than the marker). The temperature is set at 37 °C.