Diffusion behavior of lipid vesicles in entangled polymer solutions

Area of Science:

• Biophysics
• Polymer Science
• Materials Science

Background:

• Understanding particle diffusion in complex fluids is crucial for various applications.
• Phospholipid vesicles and synthetic spheres exhibit different behaviors in polymer solutions.

Purpose of the Study:

• To investigate the diffusion dynamics of phospholipid/cholesterol vesicles in aqueous polyacrylamide solutions.
• To compare vesicle diffusion with that of polystyrene (PS) latex spheres of similar sizes.

Main Methods:

• Dynamic light scattering (DLS) was employed to measure the tracer diffusion coefficients.
• Experiments were conducted across a range of polyacrylamide concentrations (0.1-10 mg/ml).

Main Results:

• Polystyrene spheres and multilamellar vesicles followed the Stokes-Einstein relation.
• Unilamellar vesicles deviated from the Stokes-Einstein relation, showing less dependence on solution viscosity.
• This deviation is attributed to the ability of unilamellar vesicles to change shape.

Conclusions:

• Vesicle flexibility significantly impacts diffusion in entangled polymer solutions.
• Unilamellar vesicles navigate polymer matrices more easily than rigid spheres due to shape adaptability.
• Multilamellar vesicles, being less flexible, diffuse similarly to rigid polystyrene spheres.