Fig. 5: Hybrid plasmonic nanocoated microelectrodes.

Schematic illustration of the plasmonic optoporation platform integrated with a hippocampal neuronal culture system: a SEM image of an electrode with plasmonic 3D nanoelectrodes. b SEM cross-section view of a neuronal process (blue) engulfing two 3D nanoelectrodes (yellow). c Representation of neurons on a microelectrode array (MEA) with 3D nanoelectrodes. The 3D nanoelectrode excited with a laser records intracellular activity, while the rest of the electrode catches extracellular signals. (Reprint permitted under Term of Use from ref. ¹¹¹). Gold nanograin microelectrode: d SEM image of morphologies of Au grains on an electrode with a diameter of 10 μm. e Phase-contrast optical image of live neural networks cultured on an MEA. The inset shows a representative extracellular action potential detected from a nanograin microelectrode. f Stimulation and recordings of neuronal networks in vitro (Reprinted with permission from ref. ¹¹²). Electroplasmonic nanoantenna: g SEM image of cardiomyocyte cells cultured on an array of electroplasmonic nanoantennas (height of 45 nm, diameter of 90 nm). h Side and top views of near-field enhancement ∣E/E0∣² along the pristine nanoantenna at 678.8 nm. Finite-difference time-domain (FDTD) simulations show that plasmonic excitations lead to strong confinement of the light within the 20-nm-thick electrochromic layer. i High SNRs (~60–220) are shown for the electroplasmonic nanoantenna even for low field values (2 × 10E2 to 8 × 10E2 V/cm). j Electron micrograph of human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (iCMs) (purple) cultured on an electroplasmonic nanoantenna array. k Differential scattering signal in response to electrogenic activity of a network of cardiomyocyte cells. A strong far-field signal allowing label-free and real-time optical detection of the electrogenic activity of iCMs is obtained from substrates with electroplasmonic nanoantennas (red curve). Control measurements are performed to verify the origin of the electro-optic signal. In the absence of electroplasmonic nanoantennas, no far-field signal is detected (blue curve) (Modified and Reprinted with permission under Term of Use from ref. ¹³). Hybrid nanoplasmonic microelectrode: l Schematic illustration. m SEM images of a microelectrode having a tip coated with ~20 nm diameter colloidal gold nanoparticles (AuNPs). LSPR absorption of AuNps is shown in the inset (Reprinted (adapted) with permission from ref. ¹⁴).