Tiny magnetic discs offer remote brain stimulation without transgenes

Amazing stuff! Still seems to be kind of crude to inject tiny particles into the brain and hope for the best.

"Novel magnetic nanodiscs could provide a much less invasive way of stimulating parts of the brain, paving the way for stimulation therapies without implants or genetic modification ...

The scientists envision that the tiny discs, which are about 250 nanometers across (about 1/500 the width of a human hair), would be injected directly into the desired location in the brain. From there, they could be activated at any time simply by applying a magnetic field outside the body. The new particles could quickly find applications in biomedical research, and eventually, after sufficient testing, might be applied to clinical uses. ...

Over the past decade other implant-free methods of producing brain stimulation have been developed. However, these approaches were often limited by their spatial resolution or ability to target deep regions. For the past decade, Anikeeva’s Bioelectronics group as well as others in the field used magnetic nanomaterials to transduce remote magnetic signals into brain stimulation. However, these magnetic methods relied on genetic modifications and can’t be used in humans. ...

The structure of the new nanodiscs consists of a two-layer magnetic core and a piezoelectric shell. The magnetic core is magnetostrictive, which means it changes shape when magnetized. This deformation then induces strain in the piezoelectric shell which produces a varying electrical polarization. Through the combination of the two effects, these composite particles can deliver electrical pulses to neurons when exposed to magnetic fields. ..."

From the abstract:

"Deep brain stimulation with implanted electrodes has transformed neuroscience studies and treatment of neurological and psychiatric conditions. Discovering less invasive alternatives to deep brain stimulation could expand its clinical and research applications. Nanomaterial-mediated transduction of magnetic fields into electric potentials has been explored as a means for remote neuromodulation. Here we synthesize magnetoelectric nanodiscs (MENDs) with a core–double-shell Fe3O4–CoFe2O4–BaTiO3 architecture (250 nm diameter and 50 nm thickness) with efficient magnetoelectric coupling. We find robust responses to magnetic field stimulation in neurons decorated with MENDs at a density of 1 µg mm−2 despite individual-particle potentials below the neuronal excitation threshold. We propose a model for repetitive subthreshold depolarization that, combined with cable theory, supports our observations in vitro and informs magnetoelectric stimulation in vivo. Injected into the ventral tegmental area or the subthalamic nucleus of genetically intact mice at concentrations of 1 mg ml−1, MENDs enable remote control of reward or motor behaviours, respectively. These findings set the stage for mechanistic optimization of magnetoelectric neuromodulation towards applications in neuroscience research."

Tiny magnetic discs offer remote brain stimulation without transgenes | MIT News | Massachusetts Institute of Technology The devices could be a useful tool for biomedical research, and possible clinical use in the future.

Magnetoelectric nanodiscs enable wireless transgene-free neuromodulation (open access)

The magnetic core of the nanodisc is magnetostrictive, which means it changes shape when magnetized. The rainbow nanodisc on the right is changing shape, allowing for the pink brain neuron to be stimulated.

Fig. 4: MEND-mediated neuronal stimulation in mice.