A versatile nanoelectrode platform for electrical recording of diverse cell types

Electrical signaling governs muscle contraction, brain function, and insulin secretion. While clinical EEG/ECG techniques signify aberrant electrical activity during disease prognosis, it is unclear how single cell action potentials ≪APs≫ are affected by diseases or novel drugs. Patch clamp and microelectrode arrays preclude researchers from collecting APs from many cells for prolonged periods of time. Here, we present a higher throughput and tunable platform for obtaining electrophysiological signals from single adherent cells with millisecond resolution. Our platform contains arrays of nanopillar (NP) electrodes made using maskless photolithography and a two-step dry and wet etching technique. We optimized various surface functionalization techniques to improve adhesion of diverse cell types on our platforms. We demonstrate electrical recording from electrogenic 2D cardiac monolayers, 3D printed cardiomyocytes, neuron-like PC12 adherent cells, and bacterial biofilms. Intracellular action potentials were observed for several days in 2D monolayers and 3D-printed cardiomyocytes with altered waveform shapes, indicating differences in cytoarchitecture for drug screening. 3D cultures grown on paired-electrode platforms showed simultaneous APs and extracellular spiking within a 10-µm distance, suggesting the possibility of extrapolating APs from in vivo extracellular signals. In differentiated PC12 cells, intracellular APs were recorded over several days for the first time, and morphologies of neurites atop nanopillars were characterized using fluorescence microscopy and electron microscopy. Our platform was redesigned to house bacterial biofilms, which show membrane potential oscillations in response to high potassium flow. Biofilm electrophysiology directly influences antibiotic resistance and gut microbiome heterogeneity. The versatility of our nanopillar electrode arrays to record electrical signals from cells with a range of sizes from 2 to 30 µm in diameter offers a powerful tool for understanding how single cell electrical activity affects function and disease.