Phase transitions in phospholipid dispersions studied with an intramolecular excimer forming fluorescent probe, 1,3-bis (beta-naphthyl)propane

We introduce the use of an intramolecular excimer forming, non-conjugated bichromophoric molecule: 1,3-bis (β-naphthyl)propane as a new probe for measuring thermal phase transitions in aqueous dispersions of phospholipids.Intermolecular excimer forming systems, such as pyrene, have been intensely studied as probes for the “microfluidity” of phospholipid dispersions.The probe we used has the added advantage that intramolecular excimer formation follows a pseudomonomolecular mechanism. This makes observations independent of probe concentration and allows for minute concentrations of the probe to be used, lowering the risk of perturbation of the phospholipid phase.Phase transition temperatures determined from 1,3-bis (β-naphthyl) fluorescence are in good agreement with differential scanning calorimetry and light scattering measurements.