Researchers at Johns Hopkins University have come up with a simple way of using ultrasound to release drugs from special nanoparticles delivered into the brain. The technology would allow for targeted drug delivery, making sure the medication is delivered where the ultrasound beam is focused while preventing its from influencing the rest of the body.
The biodegradable plastic nanoparticles are made of a hydrophilic exterior, to travel through the body, and a hydrophobic interior, to contain propofol, a commonly used small molecule anesthetic tried in this study. They are too large to move through the blood-brain barrier, but the propofol inside is. An external traditional focused ultrasound machine is used to resonate the particles, heating up their interiors and expanding them in size. Once they they get large enough, they become porous and release the propofol. If this is done just where you want the drug released, it is able to escape the nanoparticle and quickly penetrate the blood-brain barrier.
So far the researchers tested the technique on laboratory rats, tagging the nanoparticles to see how they move through the brain, as well as detecting how many are trapped by the spleen and liver. They did confirm the particles don’t pass through the blood-brain barrier, but they are well contained by the liver and spleen.
Testing the effectiveness of propofol delivered in such a way, they tested the technique by inducing seizures in mice and then immediately treating them with the ultrasound activated technique. It worked remarkably well, nearly instantaneously taming the seizures.