Magnetogenetics

Magnetogenetics is the umbrella term for controlling genetically-defined neurons with externally applied magnetic fields, which pass through bone and tissue essentially unattenuated and require no implanted light source, wire, or electrode. It couples a field to a molecular transducer — most credibly a synthetic magnetic nanoparticle, more controversially an engineered iron-storage protein — that in turn gates a genetically-expressed ion channel, so that only cells carrying the transgene respond.

The field spans three physically distinct mechanisms: magnetothermal (heat dissipated by nanoparticles in an alternating field gating a thermosensitive channel), magnetomechanical (force or torque on particles gating a mechanosensitive channel), and disputed single-protein schemes built on ferritin. Its appeal is that magnetism offers the deepest, least-invasive write channel known; its liability is that the force a laboratory field can exert on a nanoscale magnetic object is extremely small, so proposed mechanisms and their reproducibility must be scrutinised with unusual care.