nanoparticle

A nanoparticle is a solid or semi-solid particle small enough to be measured in nanometres rather than micrometres — typically between about 10 and 1000 nanometres across. To picture the scale, a human red blood cell is around 7000 nanometres wide, so a nanoparticle is hundreds of times smaller than a single blood cell. In pharmaceutics it is used as a tiny container that carries, protects and delivers a drug.

The drug can sit inside the particle (entrapped or dissolved in the matrix) or stick to its outer surface (adsorbed). Because nanoparticles are so small, they have an enormous surface area for their volume, which helps poorly soluble drugs dissolve faster, and they can slip into tissues and even cells that larger particles cannot reach. Their surface can be coated or decorated to change how long they circulate and where they go.

Nanoparticle is a broad umbrella term rather than one specific thing: liposomes, polymeric nanoparticles, solid lipid nanoparticles, micelles and lipid nanoparticles are all nanoparticles built from different materials. The trade-offs — stability, drug loading, manufacturing cost and how the body handles them — depend heavily on which type and material you choose.