lipid nanoparticle
A lipid nanoparticle, or LNP, is a tiny fatty bubble that acts as a protective delivery capsule for fragile drugs, especially nucleic acids. Bare RNA and DNA are quickly destroyed in the body and cannot cross the greasy cell membrane on their own; an LNP wraps them in a fat shell, like packing a delicate parcel in bubble wrap before shipping.
An LNP is built from a few kinds of lipid working together. An ionizable lipid is the key ingredient: it is roughly neutral in the blood so the particle is well tolerated, but becomes positively charged in the acidic compartment inside a cell, helping it break out and release its cargo into the cytoplasm. Other lipids, cholesterol, and a PEG-coated lipid control the particle's size, stability, and behaviour.
LNPs made mRNA vaccines possible and are central to delivering siRNA and other genetic medicines. Their strengths are protecting the cargo and getting it inside cells; their limits are that, given intravenously, they tend to pile up in the liver, so steering them to other organs and avoiding inflammation are active areas of research.
The COVID-19 mRNA vaccines encase their mRNA in a lipid nanoparticle that shields it from enzymes and helps it enter cells to be read.
A fatty carrier that protects nucleic-acid cargo and ferries it into cells.
An LNP is a delivery system, not the active drug; it solves the toughest problem for nucleic-acid medicines, which is getting them safely inside cells.