polymeric nanoparticle

A polymeric nanoparticle is a tiny ball made of long-chain plastic-like molecules called polymers, with a drug either trapped throughout the solid mass or attached to its surface. Think of a drug embedded in a sponge that has been shrunk to nanometre size: as the sponge slowly breaks down or lets liquid in, the drug seeps out gradually rather than all at once.

Two structural styles are common. A nanosphere has the drug spread fairly evenly through a solid polymer matrix, while a nanocapsule has a liquid or oily core holding the drug inside a thin polymer shell. The choice of polymer controls behaviour: biodegradable polymers such as PLGA (poly(lactic-co-glycolic acid)) erode in the body over days to weeks, giving a built-in slow, sustained release.

Compared with liposomes, polymeric nanoparticles are usually sturdier and easier to store, and their release rate can be tuned by changing the polymer's composition and molecular weight. The honest trade-offs are that some synthetic polymers and their breakdown products can provoke inflammation, drug loading is often modest, and removing the organic solvents used in manufacture must be done carefully.