A membrane voltage nanosensor including an inorganic semiconductor nanoparticle functionalized with a rationally designed peptide. The peptide enables the nanosensor to self-insert into and through a lipid membrane and with a desired orientation (i.e., perpendicular to the membrane normal). Once inserted, the nanosensor senses a membrane potential via a Quantum Confined Stark Effect, e.g., with a single-nanoparticle sensitivity. Example systems comprising one or more of the nanosensors could be used to simultaneously record action potentials from multiple neurons in a large field-of-view over a long time duration, or to record electrical signals on the nanoscale (such as across one synapse).
