Tools for Non-Invasive Communication with Electrogenic Cells: Optogenetic Stimulation and Diamond Recording Devices

The extension of Ch2opt_mKATE expression in electrogenic cells shows that this tool has the potential for single cell level studies in cardiac and neural tissues. The illumination area is of critical importance and could be optimized by using a light spot with a diameter as close to the cell diameter as possible. Decoupling the stimulation light from the objective lens would also assist consistent depolarization because the spot diameter at the membrane surface could be made independent of microscope focal volume. Both HL_1 and neurons were shown to be manipulated by light flashes when sufficient illumination areas were used. In neurons, the limiting factor for stimulation reliability is the recovery of Ch2opt_mKATE from the inactive state after illumination. This is in contrast to other published Channelrhodopsin 2 variants where slow closing kinetics or poor currents have been addressed. Finally, a MEA format with high enough sensitivity to cell signals for neuronal monitoring has been found which lacks significant NCLEs. This is the platinized, planar gold MEA, with platinized electrodes, and ONO passivation on a Borofloat glass substrate. This will allow investigations using the complimentary techniques of MEAs and optogenetics, though novel combinations are sought that also have suitable resistance to photovoltaic and photoelectric effects