Inducible External Magnetic Fields Coupled to Injectable Synthetic Magnetic Nanoparticles Proposed to Replace Invasive Optogenetics as Modulators of Endogenous Ion Channel Gating

Abstract

Optogenetics is poised to revolutionize the study of neural circuits and their roles in vivo. Two main components of this approach are indicated by that name. The first component is a light-gated ion channel gene (ICG) transfected into targeted neural circuits. The second, following gene transcription/translation, is an optical source focused on the transfected neural tissue. Light pulses gate transfected ion channel proteins leading to modulation of the host neuron's membrane potential (Na-selective ICG= depolarization and nerve cell excitation; K-selective ICG= hyperpolarization and nerve cell inhibition). Electrical signaling in untransfected neurons in synapse with transfected neurons is, in turn, modulated. The ultimate outcome of Optogenetics is a change in physiology or behavior supported by the targeted neural circuitry. Application of a magnetic field in close proximity to channel-attached magnetic nanoparticles is proposed as an innovation of Optogenetics. Such magnetic field gating of ion channels has advantages over Optogenetics. Most significantly, in contrast to invasive Optogenetics, magnetic field gating is speculated to gate ion channels by external, non-invasive magnetic fields. Commercially available magnetic nanoparticles make possible the essential magnetic field/ion channel connection. Magnetic field gating is proposed to innovate neuroscience research far beyond the limitations of Optogenetics. Furthermore, future translation of magnetic field gating technology to the health care market is far more practical than translation of invasive Optogenetics technology. Current applications using magnetic nanoparticles are described that lend credence to the hypothesis that magnetic fields can gate in vivo ion channels via attached magnetic nanoparticles. Magnetic field gating technology and technical challenges of developing this approach to gating ion channels are presented.