Hybrid Electro-Plasmonic Stimulation of Primary Neurons

Biomedical prosthetics utilizing electrical stimulation have limited, effective spatial resolution due to spread of electrical currents to surrounding tissue, causing nonselective stimulation. So, precise spatial resolution is not possible for traditional neural prosthetic devices, such as cochlear implants. More recently, alternative methods utilize optical stimulation, mainly infrared, sometimes paired with nanotechnology for stimulating action potentials, which has its own drawbacks, as it may heat surrounding tissue. Recently, we employed plasmonic stimulation methods utilizing gold nanoparticle-coated nanoelectrodes to convert visible light pulses into localized surface plasmon resonance transduction for stimulation of electrically excitable cells, which had limited success. Here, we report the development of a next-generation hybrid electro-plasmonic stimulation platform for spatially and temporally precise neural excitation. Trigeminal neurons were co-stimulated in-vitro in a whole-cell patch-clamp configuration with sub-threshold-level short duration electrical and visible light pulses (1-5 ms, 1-5 V, 10 Hz) aimed at a gold-nanoparticle coated nanoelectrode placed adjacent to a neuron. Membrane action potentials were recorded with a higher success rate and better post-stimulation cell recovery than with pure optical stimulation, while reducing the electrical stimulus input by up to 40%. Sub-threshold levels of electrical stimuli in conjunction with visible light (532 nm) reliably triggered trains of action potentials. Our hybrid neurostimulation findings open up opportunities for development of new generation high-acuity neural modulation prosthetic devices, tunable for individual needs, which would qualify as preferred alternative over traditional electrical stimulation technologies