Millisecond-Resolved Electronic pH Microdomains Synchronize Calcium Amplification in Cell Clusters

A central goal for bioelectronic interfaces is to convert electrical inputs into local chemical commands that regulate cell signaling with defined space and time. However, imposing spatially confined extracellular pH (pHo) cues across cell populations with externally programmed millisecond timing remains difficult. Here, we show that an electronically generated pHo microdomain can act as a timed biochemical command that synchronizes intracellular Ca2+ amplification in HL-1 cardiomyocyte clusters. Using a microfabricated electrochemical interface, electronic stimulation produced a spatially confined pHo cue, followed by coordinated Ca2+ elevation and a pronounced abrupt-amplification phase that emerged at 33 ± 13 ms after stimulation onset. Pharmacological dissection identified ryanodine receptor-mediated calcium-induced calcium release as the dominant intracellular amplifier of the fast response. These results position electronic pH modulation as a route for translating electrical inputs into spatially defined, millisecond-timed biochemical commands for synchronized control of intracellular signaling in cell populations.