Fluorescence depolarization studies of phase transitions and fluidity in phospholipid bilayers. 2. Two-component phosphatidylcholine liposomes

Abstract

The fluorescence deplorarization associated with the hydrophobic fluorescent probe 1,6-diphenyl-1,3,5-hexatriene is used to monitor changes in fluidity accompanying the gel-liquid crystalline phase transition in phosphatidylcholine dispersions. In this way, the parameters of the phase transition are determined for both large, multilamellar liposomes and small, single-lamellar vesicles composed of three mixtures of phosphatidycholines: dimyristoyl-dipalmitoyl, dimyristoyl-distearoyl, and dioleyl-dipalmitoyl. Phase diagrams for these mixed-lipid vesicles are constructed by plotting the delimiting temperatures of the phase transition vs. the lipid compostion of the vesicle. The phase diagrams are interpreted to suggest that the miscibilities of the lipids studied are markedly different in small, single-lamellar vesicles and large multilamellar liposomes. These results are discussed in terms of the effects of high curvature on the structure of biological membranes.

A Simplified Sum-Frequency Vibrational Imaging Setup Used for Imaging Lipid Bilayer Arrays

“…There is a slight but not significant decrease in the sum-frequency intensity for the DOPC:DSPC spots from 0.27 ± 0.09 to 0.21 ± 0.07. These results are consistent with the reported T m of these binary mixtures. , …”

“…The detected signal suggests phase segregation exists between DSPC:DOPC and DOPC:DPPC while the lack of signal from DMPC:DSPC implies one homogeneous phase at 20 °C. This is consistent with the phase diagrams of identical lipid compositions presented in the literature. ,, …”

A Simplified Sum-Frequency Vibrational Imaging Setup Used for Imaging Lipid Bilayer Arrays

“…There is a slight but not significant decrease in the sum-frequency intensity for the DOPC:DSPC spots from 0.27 ± 0.09 to 0.21 ± 0.07. These results are consistent with the reported T m of these binary mixtures. , …”

“…The detected signal suggests phase segregation exists between DSPC:DOPC and DOPC:DPPC while the lack of signal from DMPC:DSPC implies one homogeneous phase at 20 °C. This is consistent with the phase diagrams of identical lipid compositions presented in the literature. ,, …”

Changes Caused by Liposomes to the Belousov–Zhabotinsky Reaction

“…The reported anisotropy values of DPH in DPPC (s o phase) were 0.29–0.30, , which is well consistent with our results. Among s o phase liposomes (DPPC, DSPC), the fluidity difference was negligible while the GP 340 values were slightly different.…”

Label-Free Coherent Anti-Stokes Raman Scattering Imaging of Coexisting Lipid Domains in Single Bilayers

“…To verify that what we observed was due to phase segregation, a temperature control experiment was performed by using a home-built water bath chamber. The domains in the GUVs disappeared at 36 °C (data not shown), consistent with the phase diagram reported before …”

A Simplified Sum-Frequency Vibrational Imaging Setup Used for Imaging Lipid Bilayer Arrays

“…There is a slight but not significant decrease in the sum-frequency intensity for the DOPC:DSPC spots from 0.27 ± 0.09 to 0.21 ± 0.07. These results are consistent with the reported T m of these binary mixtures. , …”

“…The detected signal suggests phase segregation exists between DSPC:DOPC and DOPC:DPPC while the lack of signal from DMPC:DSPC implies one homogeneous phase at 20 °C. This is consistent with the phase diagrams of identical lipid compositions presented in the literature. ,, …”

Changes Caused by Liposomes to the Belousov–Zhabotinsky Reaction

“…The reported anisotropy values of DPH in DPPC (s o phase) were 0.29–0.30, , which is well consistent with our results. Among s o phase liposomes (DPPC, DSPC), the fluidity difference was negligible while the GP 340 values were slightly different.…”

Label-Free Coherent Anti-Stokes Raman Scattering Imaging of Coexisting Lipid Domains in Single Bilayers

“…To verify that what we observed was due to phase segregation, a temperature control experiment was performed by using a home-built water bath chamber. The domains in the GUVs disappeared at 36 °C (data not shown), consistent with the phase diagram reported before …”

A Simplified Sum-Frequency Vibrational Imaging Setup Used for Imaging Lipid Bilayer Arrays

“…There is a slight but not significant decrease in the sum-frequency intensity for the DOPC:DSPC spots from 0.27 ± 0.09 to 0.21 ± 0.07. These results are consistent with the reported T m of these binary mixtures. , …”

“…The detected signal suggests phase segregation exists between DSPC:DOPC and DOPC:DPPC while the lack of signal from DMPC:DSPC implies one homogeneous phase at 20 °C. This is consistent with the phase diagrams of identical lipid compositions presented in the literature. ,, …”

Changes Caused by Liposomes to the Belousov–Zhabotinsky Reaction

“…The reported anisotropy values of DPH in DPPC (s o phase) were 0.29–0.30, , which is well consistent with our results. Among s o phase liposomes (DPPC, DSPC), the fluidity difference was negligible while the GP 340 values were slightly different.…”

Label-Free Coherent Anti-Stokes Raman Scattering Imaging of Coexisting Lipid Domains in Single Bilayers

“…To verify that what we observed was due to phase segregation, a temperature control experiment was performed by using a home-built water bath chamber. The domains in the GUVs disappeared at 36 °C (data not shown), consistent with the phase diagram reported before …”