Introducing a fusogenicity metric for lipid nanoparticle formulation

Area of Science:

• Biophysics
• Materials Science
• Drug Delivery

Background:

• Lipid nanoparticles (LNPs) are highly effective drug carriers, but optimizing their lipid formulations for efficient drug release remains a challenge.
• Current methods lack quantitative measures for fusogenicity, hindering the development of improved LNP formulations.
• Understanding lipid behavior and membrane interactions is crucial for advancing drug delivery technologies.

Purpose of the Study:

• To introduce a novel framework utilizing small angle X-ray scattering (SAXS) to quantitatively measure the fusogenicity of lipids used in LNP formulations.
• To establish a reliable method for assessing the spontaneous curvature (Q) of lipids, a key indicator of fusogenicity.
• To validate the SAXS-based framework against established fusion assays and imaging techniques.

Main Methods:

• Employed small angle X-ray scattering (SAXS) to measure the spontaneous curvature (Q) of lipid mixtures, including glycerol monooleate (GMO), SM-102, and ALC-0315.
• Analyzed changes in cubic lattice parameters with temperature for GMO-containing lipid mixtures.
• Quantified the fusogenicity of ionizable lipids (SM-102, ALC-0315) by observing their effect on host membranes via SAXS.

Main Results:

• The SAXS-derived Q parameter quantitatively correlated with LNP fusogenicity, as validated by fluorescence-based fusion assays and cryogenic electron microscopy.
• The framework successfully quantified the fusogenicity of key LNP lipids like GMO, SM-102, and ALC-0315.
• Demonstrated that changes in cubic lattice parameters with temperature directly reflect fusogenic potential.

Conclusions:

• The developed SAXS-based framework provides a robust and quantitative method for measuring LNP lipid fusogenicity.
• This approach enables researchers to optimize LNP formulations for improved drug release and delivery efficiency.
• The findings enhance the fundamental understanding of lipid behavior and membrane fusion processes relevant to LNP technology and biomembranes.