Ferrimagnetic Vortex Nanorings Facilitate Efficient and Safe Deep-Brain
Magnetothermal Stimulation in Freely Moving Mice
Abstract
Magnetothermal neuromodulation is a minimally-invasive, deep-brain
accessible and tether-free technique. The precisely timed activation of
thermosensitive ion channels, such as TRPV1, with local heat generated
using magnetic nanoparticles is crucial for efficient neuromodulation.
Nevertheless, this technique is greatly hindered by its long
stimulus-response time and high safety risks due to the poor
heat-generating performance of the nanomediators. Herein, we report the
establishment of a ferrimagnetic vortex iron oxide nanoring
(FVIO)-mediated magnetothermal neurostimulation technique that is
efficient and safe. Compared with widely used superparamagnetic iron
oxide nanomediators (SPIOs), the FVIOs triggered Ca2+ influx into
HEK293T cells and cortical neurons at an Fe concentration of 54 μg/mL,
which is 20.27-fold lower than that needed for SPIOs. In vivo
magnetothermal stimulation in the central nucleus of the amygdala of
mice further demonstrated that FVIOs with the optimal dose of 0.05 μg
evoked fear behaviors with an average latency of 2.51 s, which was
2.3-fold faster than that in the SPIO (0.8 μg)-treated group. More
importantly, FVIOs-mediated stimulation not only exhibited negligible
histopathological alterations and proinflammatory cytokine expression,
but also successfully elicited fear behaviors in transgene-free mice.
The FVIO-mediated efficient and safe neuromodulation has the potential
for future neuroscience exploitation and neurological disease treatment.