Ultraslow dynamics of a complex amphiphile within the phospholipid bilayer: Effect of the lipid pre-transition

Abstract

The shape and intensity of fluorescence emission spectra of Merocyanine 540 embedded in dipalmitoylphosphatidylcholine bilayers differ depending on the thermal history of the sample. This apparent hysteresis in fluorescence emission was most prominent in the temperature range of 20 to 35°C. Analysis of kinetic and temperature cycling experiments suggested that Merocyanine 540 slowly (half time of about 30min) assumes a metastable configuration as temperature is raised above the phospholipid pre-transition point. When the sample was cooled below the pre-transition temperature, the metastable state slowly depopulated (half time of about 15min). The rate of merocyanine exchange among these states was influenced more by membrane lipid mobility than by lipid order since cholesterol increased the rate of transition to the metastable state by a factor of 11.

Exposure to Aldehyde Cherry e-Liquid Flavoring and Its Vaping Byproduct Disrupt Pulmonary Surfactant Biophysical Function

“…These were performed with quasistatic LBT compression rates to allow the observation of fine molecular interactions. 51,52 In the Π−A isotherm measured during the first cycle, there was a clear decrease in the Π max when either BA or BPGA was added (Figure 1A). Therefore, the interaction of BA and BPGA with surfactant lipids prevents the achievement of higher surface pressures.…”

“…We performed 10 consecutive compression–expansion cycles (Π– A iso-cycles), as monolayer constituent refinement is known to be an important property of a lung surfactant (Supporting Information Figure S1). These were performed with quasi-static LBT compression rates to allow the observation of fine molecular interactions. , In the Π– A isotherm measured during the first cycle, there was a clear decrease in the Π max when either BA or BPGA was added (Figure A). Therefore, the interaction of BA and BPGA with surfactant lipids prevents the achievement of higher surface pressures.…”

Exposure to aldehyde cherry e-liquid flavouring and its vape by-product disrupts pulmonary surfactant biophysical function

“…Quasi-static LBT compression rates allow the observation of fine molecular interactions. 51,52 In the Π − A isotherm measured during the first cycle, there was a clear decrease in the Π max when either BA or BPGA was added (Fig. 1A).…”