pH modulation in adhesive cells with a protonic biotransducer

Protons (H⁺) are essential for most physiological functions in organelles and cells. In this study, we have demonstrated a sulfonated polyaniline (SPA) biotransducer that can modulate the intracellular pH in C6 cells with an applied potential, which is directly coupled with H⁺ to facilitate engineering interactions with physiological processes in the cells. To modulate the pH in the intracellular fluid, we improved the performance of SPA biotransducer by coating of a carbon nanotube (CNT) supportive layer that provides high H⁺ selectivity in the solution and also high H⁺ capacity in the hybrid SPA electrode. The intracellular pH modulation was succeeded by applying a potential difference of less than ±0.6 V. pH modulation in the cells is effected by using the biotransducer, which drives the activity of plasma membrane potential and the flow of molecules through the permeable membrane between cells and culture medium, whereas the poly (3,4-ethylenedioxythiophene) (PEDOT)-based biotransducer, which does not have H⁺ selectivity, was insufficient for modulation. Furthermore, the protonic biotransducer can control the increase/decrease in mitochondria membrane potential, reactive oxygen species and intracellular Ca²⁺ concentration. Therefore, the protonic biotransducer provides a new perspective to transfer a H⁺ signal into the cells for modulating the functions.