Quantitative Raman microspectroscopy for water permeability parameters at a droplet interface bilayer.

Area of Science:

• Biophysics
• Physical Chemistry
• Materials Science

Background:

• Understanding water transport across lipid bilayers is crucial for cell physiology and drug delivery.
• Droplet interface bilayers (DIBs) offer a model system to study bilayer properties.
• Accurate measurement of water permeability coefficients is essential for these studies.

Purpose of the Study:

• To develop and apply a novel method for determining water permeability coefficients of lipid bilayers.
• To investigate water and D2O transport across nanoliter aqueous droplet pairs forming a DIB.

Main Methods:

• Utilized confocal Raman microspectroscopy to monitor changes in solute concentration.
• Employed the C≡N stretching mode of K3Fe(CN)6 as a reporter for water uptake.
• Measured O-D Raman signals to determine passive diffusional permeability of D2O.

Main Results:

• Successfully derived water permeability coefficients for a DIB using Raman scattering.
• Quantified the passive diffusional permeability coefficient for D2O transport across the DIB.
• Demonstrated the reliability and convenience of the Raman microspectroscopy method.

Conclusions:

• Confocal Raman microspectroscopy provides a significant methodological advance for measuring water permeability.
• This technique offers a convenient and reliable way to determine bilayer water transport parameters.
• The study validates DIBs as a model system for biophysical investigations.