Magnetoelectric Nanoparticles Enable Modulation of Cortical Networks by Low-Intensity Static Magnetic Fields In Vitro.

Achieving precise and minimally invasive control of brain activity remains a major challenge in neuroscience, with current non-invasive techniques offering limited spatial and temporal resolution. Here, this study investigated whether magnetoelectric nanoparticles (MENPs) can extend the effective neuromodulation range of static magnetic fields, enabling modulation under intensities (<100 mT) that are otherwise biologically inert. To this end, MENPs comprising a cobalt ferrite magnetostrictive core and a piezoelectric barium titanate shell were fabricated. Using magnetoelectric modeling, the non-negligible electric fields generated by individual MENPs under magnetic-field strengths used experimentally were estimated. The ability of MENPs to modulate cortical network activity in spontaneously rhythmic cortical slices under low-intensity static magnetic fields was tested. Using electrophysiological recordings, network activity was directly measured before, during, and after stimulation. Magnetic fields alone did not alter neuronal activity at the intensities used. In contrast, in the presence of MENPs, the same fields activated the network, enhancing the frequency of spontaneous rhythmic activity and thus network excitability. These findings demonstrate that MENPs lower the threshold for magnetic neuromodulation, providing a mechanistic link between weak magnetic inputs and network-level brain activity. This work position MENPs as a promising strategy for the wireless modulation of neuronal network dynamics, with the potential to reach deep brain circuits.