Statistical Analysis of Bending Rigidity Coefficient Determined Using Fluorescence-Based Flicker-Noise Spectroscopy

Area of Science:

• Biophysics
• Materials Science

Background:

• Bending rigidity coefficient quantifies lipid bilayer deformability, crucial for membrane function.
• Measuring this parameter requires advanced techniques like flicker-noise spectroscopy and giant unilamellar vesicles (GUVs).
• Challenges include GUV size variability and compositional homogeneity in lipid mixtures.

Purpose of the Study:

• To measure the bending rigidity coefficient of lipid bilayers using fluorescence-enhanced flicker-noise spectroscopy.
• To statistically analyze large populations of GUVs to determine the appropriate distribution for rigidity coefficient calculation.
• To assess vesicle population homogeneity and the influence of fluorescent labels and instrumental setups.

Main Methods:

• Utilized fluorescence-enhanced flicker-noise spectroscopy for measuring membrane bending rigidity.
• Applied the giant unilamellar vesicles (GUV) model with large populations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine.
• Performed statistical analysis on experimental data to identify distribution characteristics.

Main Results:

• Demonstrated that the bending rigidity coefficient exhibits an asymmetrical distribution, well-approximated by a gamma distribution.
• Proposed using the difference between normal and gamma fits as a metric for vesicle population homogeneity.
• Found that the bending rigidity coefficient is independent of the fluorescent label and microscope type used.

Conclusions:

• The gamma distribution accurately describes the bending rigidity coefficient of GUVs.
• The proposed method offers a way to quantify vesicle population homogeneity.
• Experimental conditions like fluorescent labels and instrumental setups do not significantly affect the measured bending rigidity coefficient.