Liposomes
"Liposome" is a general term for vesicles that are formed by a lipid bilayer and that contain an aqueous core
Materials can be loaded either into the aqueous core of the liposome (hydrophilic) or into the lipid bilayer (hydrophobic).
All liposomes are composed of lamella, or layers.
Liposomes are usually around 80nm in size.
Micelles
Micelles have hydrophilic head region in contact with the polar solvent and the hydrophobic tail region sequestered away from the solvent.
Micelles have a solid lipid core,which can be used to sequester hydrophobic APIs.
Micelles are usually formed by single-chain lipids or lipids with large headgroups due to lipid geometry and the high curvature of micelles.
LNPs
LNPs, short for lipid nanoparticles, is the term currently used to describe solid-core lipid vesicles encapsulating negatively charged nucleic acid cargo.
LNPs can be composed of many different lipid classes and structures, but always utilize a cationic lipid to allow for condensation of anionic nucleic acids, thereby forming the solid core particles.
LNPs are typically made using solvent injection. LNPs are usually around 80nm in size.
Multilamellar
Multilamellar vesicles have many lamellae (or bilayers). Think of an onion!
These are generally in the 1-5um size range.
The benefit to MLVs is that you can typically have a higher drug concentration because you can pack drug into the aqueous layer between each bilayer.
GUVs
GUVs or Giant Unilamellar Vesicles are microns-scale vesicles that have a single bilayer.
Primarily used to observe lipid phase behavior and membrane events (fusion, fission) in synthetic biology with fluorescence microscopy.
Methods of preparation: swelling, electroformation
Generally, 1-30µm
MVLs
MVLs, or Multivesicular liposomes, are large spherical vesicles with smaller polygon-shaped compartments, each containing API.
These vesicles offer benefits such as increased drug loading, sustained release, and prolonged efficacy.