summary: Scientists have developed magnetic nanodiscs that enable targeted brain stimulation without the need for invasive implants or genetic modifications. The tiny discs, activated by an external magnetic field, deliver electrical impulses to nerve cells, showing potential for treating neurological conditions.
Initial tests in mice showed that these nanodiscs effectively stimulated areas of the brain associated with reward and motor control, with fewer responses to foreign objects than traditional implants. The study represents a step toward new, less invasive treatments for brain disorders.
Future improvements aim to enhance the electrical pulse output of the discs for greater effectiveness. With further research, these nanodiscs could become valuable tools in neurological research and treatments.
Key facts:
- Nanodiscs provide electrical stimulation when activated by an external magnet.
- Tests conducted on mice showed effective stimulation of brain areas related to reward and motor functions.
- Future research will focus on amplifying the electrical output of nanodiscs for clinical use.
source: Massachusetts Institute of Technology
New magnetic nanodiscs could provide a much less invasive way to stimulate parts of the brain, paving the way for stimulation treatments without implants or genetic modification, researchers from MIT report.
Scientists envision that the tiny discs, about 250 nanometers wide (about 1/500 the width of a human hair), will be injected directly into the desired location in the brain. From there, they can 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, could be applied to clinical uses.
The development of these nanoparticles is described in the journal Nature nanotechnologyin a paper by Polina Anikieva, a professor in the MIT Departments of Materials Science and Engineering and Brain and Cognitive Sciences, graduate student Yi Ji Kim, and 17 others at MIT and in Germany.
Deep brain stimulation (DBS) is a common clinical procedure that uses electrodes implanted in targeted brain areas to treat symptoms of neuropsychiatric conditions such as Parkinson’s disease and obsessive-compulsive disorder.
Despite its effectiveness, the surgical difficulty and clinical complications associated with DBS limit the number of cases in which such an invasive procedure is justified. New nanodiscs could provide a smoother way to achieve the same results.
Over the past decade, other implant-free methods have been developed to produce brain stimulation. However, these methods were often limited by their spatial resolution or ability to target deep regions.
Over the past decade, Anikeeva’s Bioelectronics group, as well as others in the field, have used nanoscale magnetic materials to convert remote magnetic signals into brain stimulation. However, these magnetic methods rely on genetic modifications and cannot be used in humans.
Since all neurons are sensitive to electrical signals, Kim, a graduate student in Anikieva’s group, hypothesized that an electromagnetic nanomaterial that could efficiently convert magnetization into electrical potentials could provide a path toward remote magnetic brain stimulation. However, creating a nanoscale electromagnetic material has been an enormous challenge.
Kim assembled new electromagnetic nanodiscs and collaborated with Noah Kent, a postdoctoral researcher in Anikeeva’s lab with a background in physics and the study’s second author, to understand the properties of these particles.
The structure of the new nanodiscs consists of a two-layer magnetic core and a piezoelectric shell. A magnetic core is magnetotropic, which means that it changes shape when magnetized.
This deformation then induces stress in the piezoelectric shell that produces varying electrical polarization. By combining the two effects, these composite particles can deliver electrical impulses to neurons when exposed to magnetic fields.
One of the keys to the effectiveness of tablets is the shape of the tablet. Previous attempts at magnetic nanoparticles used spherical particles, but the electromagnetic effect was very weak, Kim says. Kent adds that this contrast enhances magnetic contraction by more than 1,000 times.
The team first added their nanodiscs to the cultured neurons, which then allowed these cells to be activated on demand using short pulses of magnetic field. This stimulation did not require any genetic modification.
They then injected small drops of the electromagnetic nanodisc solution into specific areas of the mice’s brains. Hence, simply turning on a relatively weak electromagnet nearby causes the particles to release a small shock of electricity into that area of the brain.
Stimulation can be turned on and off remotely by toggling the electromagnet. This electrical stimulation “had an effect on neuronal activity and behavior,” says Kim.
The team found that electromagnetic nanodiscs could stimulate an area deep in the brain, the ventral tegmental area, associated with feelings of reward.
The team also stimulated another area of the brain, the subthalamic nucleus, which is associated with motor control.
“This is the area where electrodes are typically implanted to manage Parkinson’s disease,” Kim explains.
The researchers were able to successfully demonstrate the modification of motor control through particles. Specifically, by injecting nanodiscs into just one hemisphere, the researchers were able to induce rotation in healthy mice by applying a magnetic field.
The nanodiscs can trigger neural activity comparable to traditional implanted electrodes that provide mild electrical stimulation. The researchers achieved sub-second temporal resolution of neural stimulation using their method, but observed significantly reduced foreign body responses compared to electrodes, which may allow for safer deep brain stimulation.
The multilayered chemical composition, shape and physical size of the new multilayered nanodiscs is what made microcatalysis possible.
While the researchers have succeeded in increasing the magnetic retraction effect, the second part of the process, converting the magnetic effect into an electrical output, still needs more work, Anikieva says.
While the magnetic response was a thousand times greater, the conversion into an electrical pulse was only four times greater than with conventional spherical particles.
“This massive thousand-fold improvement has not yet been fully translated into electromagnetic enhancement,” says Kim.
“This is where a lot of future work will be focused, on making sure that a thousand times amplification in magnetic constriction can be converted to a thousand times amplification in electromagnetic coupling.”
What the team found, regarding the way particle shapes affect their magnetic contraction, was completely unexpected.
“It’s something new that just came out when we tried to figure out why these particles work so well,” Kent says.
“Yes, it’s a record particle, but it’s not as record-breaking as it should be,” Anikieva adds. This remains a topic for further work, but the team has ideas on how to make further progress.
While it is in principle possible to apply these nanodiscs already to basic research using animal models, translating them to clinical use in humans will require several further steps, including large-scale safety studies, “something academic researchers do not necessarily have the expertise to do.” “Good situation.” “I have to,” says Anikieva.
“When we find that these particles are truly useful in a particular clinical context, we imagine there will be a path for them to undergo more rigorous large animal safety studies.”
The team included researchers affiliated with the MIT Departments of Materials Science and Engineering, Electrical Engineering and Computer Science, Chemistry, and Brain and Cognitive Sciences; Electronics Research Laboratory. McGovern Brain Research Institute; the Koch Institute for Integrative Cancer Research; From Friedrich Alexander University in Erlangen, Germany.
Financing: This work was supported in part by the National Institutes of Health, the National Center for Complementary and Integrative Health, the National Institute of Neurological Disorders and Stroke, the McGovern Institute for Brain Research, and the K. Lisa Yang and Hawke E. Tan Center for Molecular Therapeutics in Neuroscience.
About neurotechnology research news
author: David L. Chandler
source: Massachusetts Institute of Technology
communication: David L. Chandler – Massachusetts Institute of Technology
image: Image credited to Neuroscience News
Original search: Open access.
“Electromagnetic nanodisks enable gene-free wireless neuromodulation” Written by Polina Anikieva et al. Nature nanotechnology
a summary
Electromagnetic nanodisks enable gene-free wireless neuromodulation
Deep brain stimulation using implanted electrodes has transformed neuroscience studies and the treatment of neuropsychiatric conditions. Discovering less invasive alternatives to deep brain stimulation could expand its clinical and research applications. The conversion of nanomaterial-mediated magnetic fields into electrical potentials has been explored as a means of remote neuromodulation.
Here we synthesize electromagnetic nanodiscs (MENDs) using double-shell Fe3Hey4-coffee2Hey4-Patio3 Structure (diameter 250 nm and thickness 50 nm) with efficient electromagnetic coupling.
We find strong responses to magnetic field stimulation in neurons decorated with MENDs at a density of 1 μg mm-2 Although single particle potentials are below the threshold of neural excitation. We propose a model of recurrent subthreshold depolarization, which, together with cable theory, supports our observations in vitro and informs electromagnetic stimulation in vivo.
It is injected into the ventral tegmental area or subthalamic nucleus of genetically normal mice at concentrations of 1 mg.-1MENDs allow remote control of reward or motor behaviors, respectively.
These findings pave the way for improving the mechanics of electromagnetic neuromodulation toward applications in neuroscience research.
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