Force sharing between the liposome biomembrane and viscous core: an experimental study

Area of Science:

• Biomaterials Science
• Biophysics
• Drug Delivery

Background:

• Liposome mechanical properties are crucial for drug delivery efficacy.
• Current methods for assessing liposome mechanics rely on model-dependent assumptions.
• Deconvolving membrane and core contributions to liposome stiffness is challenging.

Purpose of the Study:

• To introduce a novel, experimental method to isolate the mechanical contribution of the liposome core.
• To quantify the effect of a viscoelastic core on liposome mechanics.
• To enable model-independent characterization of filled liposome biomechanics.

Main Methods:

• Fabrication of giant unilamellar vesicles (GUVs) with buffer or hyaluronic acid (HA) cores.
• Characterization using atomic force microscopy (AFM).
• Isolation of core contribution by subtracting force response of buffer-filled GUVs from HA-filled GUVs.

Main Results:

• A novel, model-independent method was established to isolate the core's mechanical contribution.
• The hyaluronic acid core significantly increases liposome resistance to deformation.
• The viscous core dominates mechanical load-bearing at large deformations (>150 nm), contributing over 80%.

Conclusions:

• Liposome membrane stiffness is dominant for small deformations (<25 nm).
• Viscoelastic cores play a critical role in the mechanical properties of liposomes at larger deformations.
• This method facilitates understanding liposome biomechanics and engineering drug carriers with tuned mechanical properties.