Bioelectronic control of chloride ions and concentration with Ag/AgCl contacts

Translation between ionic currents and measurable electronic signals is essential for the integration of natural systems and artificial bioelectronic devices. Chloride ions (Cl−) play a pivotal role in bioelectricity, and they are involved in several brain pathologies, including epilepsy and disorders of the autistic spectra, as well as cancer and birth defects. As such, controlling [Cl−] in solution can actively influence biochemical processes and can be used in bioelectronic therapies. Here, we demonstrate a bioelectronic device that uses Ag/AgCl contacts to control [Cl−] in solution by electronic means. We do so by exploiting the potential dependence of the reversible reaction, Ag + Cl− ↔ AgCl + e−, at the contact/solution interface, which is at the basis of the well-known Ag/AgCl reference electrode. In short, a negative potential on the Ag/AgCl contact transfers Cl− from the contact to the solution with increasing [Cl−] and vice versa. With this strategy, we demonstrate precise spatiotemporal control of [Cl−] in solution that can be used to affect physiological processes that are dependent on [Cl−]. As proof-of-concept, we use [Cl−] control to influence the membrane voltage on human pluripotent stem cells.