Phase partitioning of TopFluor-Chol and TopFluor-SM in solid-supported lipid bilayers under varying membrane hydration state

Partitioning coefficients (xLo, xLd) of 23-(dipyrrometheneborondifluoride)-24-norcholesterol (TopFluor-Chol) and N-[11-(dipyrrometheneboron difluoride)undecanoyl]-D-erythro-sphingosylphosphorylcholine (TopFluor-SM) in the liquid-ordered (Lo) and liquid-disordered (Ld) phases within the phase-separated solid-supported lipid bilayer composed of an equimolar mixture of 1,2-dimyristoleoyl-sn-glycero-3-phosphocholine, cholesterol, and egg sphingomyelin equilibrated in atmosphere of different relative humidity levels during dehydration and rehydration. Each data point represents the partitioning coefficient calculated based on the average fluorescence intensities from at least 6 spots of distinct phase from each sample at a specific membrane hydration state. The number of samples varies with membrane hydration state, ranging from 1 to 3.