USDThe concept of a liposome is simple. Phospholipids have one hydrophobic and hydrophilic end. In solution, they naturally form a structure called a liposome, because the ends are attracted to the same end of the other particles.
A liposome is a structure made of at least one phospholipid bilayer. In structure, they resemble a cell membrane. This makes them biocompatible and less likely to be noticed by the immune system. The structure of the liposome with hydrophilic and hydrophobic ends makes them useful for forming stable emulsions and encapsulating a wide variety of ingredients. Lipid nanoparticles are similar to liposomes but are typically loaded with active ingredients.
When encapsulating something in a liposome or LNP, there are variety of options to explore and vocabulary to understand.
Structure
The first way to classify liposomes is by size and then the number of layers. A unilamellar vesicle has one bilayer. A multilamellar vesicle has multiple consecutive bilayers, and a multivesicular vesicle has multiple non-consecutive bilayers. These internal vesicles can be used to engineer multistage ingredient release
Varying methods, like sonication, homogenization, microfluidic chip methods and extrusion, can be used to prepare and change the size of a liposome. Size of liposome impacts encapsulation efficiency, circulation time. Many clients in the use liposomes or LNPs around 200nm diameter.
Construction
LNPs differ in how they are made. Methods include thin film, solvent injection, detergent removal, heating and pH methods, microfluidic channel and supercritical fluid.
Then there are methods used to increase encapsulation, improve stability and reduce liposome size. These include freeze-thaw cycles, lyophilization and extrusion.
Payload
LNPs can carry many different active ingredients, including hydrophobic and hydrophilic. Bubble liposomes can encapsulate gas. For example, nitric oxide bubble liposomes. Solid lipid nanoparticles have a solid core.
Charge
LNPs can also incorporate a cationic (positive) or anionic (negative charge), like magnets. Charged LNPs have certain advantages. The first is that the charged particles reduce aggregation because the same-charge particles repel each other. For example, cationic liposomes can encapsulate nucleic acids (how does this work). Anionic liposomes are better at crossing the skin barrier than neutral liposomes.
While a standard liposome has a neutral charge, liposomes can be prepared to be cationic (positively charged) or anionic (negatively charged) as well. These charged liposomes have advantages in certain scenarios. The first is that the charged particles reduce aggregation because the same-charge particles repel each other.
Surface Components
Liposome can be customized with surface components to direct them to an intended site and protect them from the immune system. For example, PEGlaytion can be used to extend circulation time. Enzymosomes contain an enzyme surface component connected to a liposome or other lipid vesicle. Liposomes can also be more actively targeted using strategies like receptor-mediated endocytosis. Some liposomes are designed to distribute their payload when certain environmental conditions are met, like pH or temperature.
Conclusion
Additionally, there are many liposome alternatives with a similar structure. An ufasome is made of fatty acids instead of phospholipids. A noisome is made of surfactants and lipids. An oleosome is a naturally occurring vesicle in plants, with a mono layer of phospholipids and a center of triacylglycerol.
The type of LNP you are looking for depends on your needs for active ingredient, release, targeting and additional factors. LNPs are a diverse tool for encapsulation with different configurations and advantages.
Sources
https://pmc.ncbi.nlm.nih.gov/articles/PMC9118483/
https://pubmed.ncbi.nlm.nih.gov/38779736/
https://pmc.ncbi.nlm.nih.gov/articles/PMC10892933/
949-932-0294 Los Angeles 
Nano@Genizer.com