Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational...

Area of Science:

• Physical Chemistry
• Biophysics
• Materials Science

Background:

• Lipid bilayers are fundamental components of cell membranes.
• Understanding their structural dynamics is crucial for biological function.
• Vesicle size can influence membrane properties and dynamics.

Purpose of the Study:

• To directly measure ultrafast structural dynamics within lipid bilayers.
• To investigate the influence of vesicle size on these dynamics.
• To compare the size dependence between DLPC and dipalmitoylphosphatidylcholine.

Main Methods:

• Utilized 2D IR vibrational echo spectroscopy.
• Employed tungsten hexacarbonyl as a vibrational probe for the CO stretch.
• Analyzed spectral diffusion in the alkyl region of lipid bilayers.

Main Results:

• Interior structural dynamics accelerate as vesicle size decreases.
• Size dependence of dynamics is greater for dipalmitoylphosphatidylcholine than DLPC.
• Dynamics in larger DLPC vesicles approach those of planar bilayers.

Conclusions:

• Vesicle size significantly impacts ultrafast structural dynamics in lipid bilayers.
• The distinct lipid chain lengths of DLPC and dipalmitoylphosphatidylcholine lead to different size dependencies.
• Results provide insights into membrane heterogeneity and dynamics at the nanoscale.