Cardiovascular disease is the leading cause of morbidity and mortality worldwide and is responsible for 20% of deaths in the United States alone. Among both disabling and fatal events, cardiac arrhythmias play a central role. In this context, electrophysiological studies of cardiac models of arrhythmias in vitro are essential to provide a fundamental understanding of the underlying mechanisms and develop novel therapeutics. In particular, monitoring cardiomyocyte action potential propagation at the cell network level with subcellular resolution and over extended periods is of fundamental importance to comprehend the role of gap junction distribution and sodium channel clustering, at the microscopic scale, in the activation wavefront propagation in cardiac tissue. Alas, current electrophysiological techniques suffer from severe technical limitations which prevent performing such experiments and, therefore, hinder progress in cardiovascular research. In this proposal, we introduce the concept of multi-electroplasmonic nanoantenna arrays (MENAs) to enable wireless transmembrane-level electrophysiology in networks of cells with subcellular resolution and over extended periods. MENAs are composed of protruding nanomushroom-like electroplasmonic nanoantennas designed to strengthen coupling at the cell- nanoantenna interface and provide large seal resistances with the cells cultured atop. Under such conditions, local electroporation provides direct intracellular access to the structures and permits each nanoantenna to scatter light with an intensity proportional to the cell transmembrane potential. Compared to the patch clamp technique, MENAs are not limited to a single cell at a time but permit the study of cellular networks with up to a million recording sites simultaneously. Due to their wireless nature, MENAs do not need conductive traces or integrated amplifiers, which limit the lateral resolution of traditional multielectrode arrays to ~20 µm and, consequently, can achieve sub-micrometer resolution. Furthermore, MENAs do not suffer from photobleaching and permit long-term stability much greater than fluorescence-based reporters, such as voltage-sensitive dyes (up to several days versus a few minutes, respectively). Compared to recent electro-optic approaches limited to single-site extracellular recordings, MENAs provide intracellular access and permit multi-site transmembrane-level electrophysiology. The following three aims will be achieved to demonstrate the concept of MENAs: Aim 1 – Nanofabrication and electro-optic characterization of MENAs: A scalable nanofabrication process will be developed to manufacture MENAs. Electro-optic performances of the resulting nanotransducers will be characterized. Aim 2 – Characterization of MENA electrophysiological recording properties with cardiomyocyte monolayers: MENAs recordings will be studied in terms of amplitude, duration, and yield and validated with patch clamp experiments. Aim 3 – Proof-of-concept ...