blood–brain barrier (BBB)

A tightly sealed lining of the blood vessels in the brain that keeps most substances in the blood from reaching brain tissue. It protects the brain from toxins and infection, and it also blocks most medicines.

Getting particles across it is one of the main goals, and main obstacles, of nanotechnology aimed at the brain. Researchers have tested particles that cross it with the help of a magnet or focused ultrasound in animals. A 2019 proposal for future brain-linked nanorobots assumed they would cross it; nothing of that kind has been built.

Related terms: nanoparticle, nanomedicine, magnetoelectric nanoparticles, neuralnanorobotics

Sources: Blood–brain barrier — Wikipedia; Human Brain/Cloud Interface — Frontiers in Neuroscience (2019)