Magnetoelectric nanodiscs stimulate deep brain noninvasively

According to the latest issue of Nature Nanotechnology magazine, researchers at the Massachusetts Institute of Technology have developed a new type of magnetoelectric nanodisc that provides a new method for non-invasive brain stimulation, which is expected to replace traditional implantable or genetic modification therapies.

Deep brain stimulation (DBS) is a procedure that implants electrodes in targeted brain regions to treat neurological and psychiatric disorders such as Parkinson's disease and obsessive-compulsive disorder. Despite its remarkable efficacy, the difficulty of DBS surgery and potential complications limit the application of this invasive procedure.

The new magnetoelectric nanodiscs offer a gentler and non-invasive way to achieve a similar effect. These nanodiscs consist of a double-layer magnetic core and a piezoelectric shell, and are about 250 nanometers in diameter, just 1/500 the width of a human hair. They can be injected directly into specific brain areas and activated at any time by applying a magnetic field outside the body. The magnetic core is magnetostrictive, which means it changes shape when magnetized.

The disc shape is one of the key factors for its high efficiency. The spherical magnetic nanoparticles used previously have a very weak magnetoelectric effect. The anisotropy of the disc shape enhances the magnetostrictive effect by more than 1,000 times.

In the experiment, the researchers first added the nanodiscs to cultured neurons and activated these cells on demand using short pulses of magnetic fields. This stimulation does not require any genetic modification. They then injected a small drop of the magnetoelectric nanodisc solution into a specific area of ​​the mouse brain. Simply turning on a weaker electromagnet nearby can trigger the particles to release a weak electric shock in that brain area. This stimulation can be turned on and off remotely by switching the electromagnet.

The magnetoelectric nanodiscs were able to stimulate a deep brain region associated with reward perception, the ventral tegmental area. In addition, the researchers stimulated another brain region associated with motor control, the subthalamic nucleus, which is where electrodes are usually implanted in Parkinson's patients. The results showed that the researchers successfully modulated motor control and were even able to use magnetic fields to induce rotation in healthy mice after injecting the nanodiscs into one hemisphere of their brains.

This innovative technology not only provides new possibilities for the treatment of neurological diseases, but also opens up new avenues for future non-invasive brain science research.