Magnetoelectric Neural Modulation

Abstract

Optocapacitance is a technique whereby flash illumination quickly changes membrane capacitance to elicit action potentials (APs) in unmodified (not genetically engineered) excitable cells. Spherical 20-nm gold nanoparticles (AuNPs) interfaced with the plasma membrane serve as light absorbers to induce AP generation in response to 1-ms, 100 mJ, 532-nm laser pulses. Light absorption by the AuNP produces localized heating that changes local temperature by <2C. This increases membrane capacitance, and a resulting depolarizing membrane current (VdC/dt; proportional to the rate of temperature change; Nat. Commun., 2012;3:736) induces opening of voltage-gated sodium channels and thus AP initiation in neurons (Neuron, 2015;86:207-17). Here we present new findings obtained from dorsal root ganglion (DRG) cells, by varying the flash wavelength, light-absorbing particle, and flash duration. Using cylindrical AuNPs (nanorods; 25x94 nm; plasmon absorbance peak at~780 nm), a 1-ms, 20 mJ, 785-nm laser pulse was sufficient to elicit APs. A single 1-2 mm graphite particle placed on the DRG cell induced AP generation upon delivery of a 532-nm laser flash of 4 ns duration and 47 nJ energy, representing 130-fold less energy than the 6.2 mJ needed with a 0.5-ms laser pulse. With AuNPs, reduction in flash duration similarly decreased the flash energy required for AP generation. Our data demonstrate the use of near-infrared flashes that penetrate deeper into tissue than green light to elicit APs with light. They also indicate that, in addition to gold and mesoporous silicon (Nat. Mater., 2016;15:1023-30), graphite can enable optocapacitive AP generation. The data furthermore show that, with~nanosecond flash durations, APs can be elicited by flashes of~nano-Joule energy, i.e., in the range of those used in optogenetic approaches. Support: NIH grants R21-EY023430, R01-GM030376, and the Beckman Initiative for Macular Research.

Microfluidic Processing of Piezoelectric and Magnetic Responsive Electroactive Microspheres

“…Metabolic activity of RC was improved by a minimum of 1.2-fold in the presence of PVDF or PVDF–CFO microspheres, thus demonstrating its enhancement relative to the control (microsphere absence), which proves the materials’ cytocompatibility on direct contact. Although CFO’s cytotoxic effects are described in the literature, in our case, no negative effects were observed even though CFO clusters were observed on the PVDF–CFO microsphere’s outer and inner surfaces (Figure ), thus proving the strong encapsulation/retention provided by the polymer’s matrix during culture conditions. , …”

Tailored Biodegradable and Electroactive Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Based Morphologies for Tissue Engineering Applications

“…It is verified that all the samples do not show any cytotoxic effect (cell viability values higher than 70%). Regarding the samples with CFO in the polymer matrix, it is thus deduced that the particles are efficiently encapsulated, once these particles are cytotoxic [ 20 , 21 ]. In this way, these samples can be used for biomedical applications, and more particularly for tissue engineering applications.…”

“…These materials can convert magnetic stimuli into electrical stimuli [ 19 ], producing local electric potentials upon magnetic stimulation [ 20 ]. Magnetoelectric materials have shown its relevance in neural [ 21 ], bone [ 18 , 22 ], and muscle [ 22 ] engineering.…”

Tailored Biodegradable and Electroactive Poly(hydroxybutyrate-co-hydroxyvalerate) Based Morphologies for Tissue Engineering Applications

“…It is verified that all the samples do not show any cytotoxic effect (cell viability values higher than 70%). Regarding the samples with CFO in the polymer matrix, it is thus deduced that the particles are efficiently encapsulated, once these particles are cytotoxicity [20,21]. In this way, these samples can be used for biomedical applications, and more particularly for tissue engineering applications.…”

“…Magnetoelectric materials have shown its relevance in neural [21], bone [18,22] and muscle [22] engineering.…”