Water Electrolysis Carried Out on Microelectrodes to Obtain New Insights into the Regulation of Cytosolic pH

摘要

In this study, the use of electrochemistry in cell biology is extended by showing that electrochemically generated microscale pH gradients can be used to gain new insights into the regulation of cytosolic pH of normal and cancer cells. The developed procedure involves positioning a carbon fiber microelectrode into the extracellular space of adherently growing cells and setting its potential to values suitable for electrooxidation or electroreduction of water. While the electrooxidation of water decreases the pH of the solution surrounding the microelectrode (because it produces hydronium ions), the electroreduction of water increases the pH of the same solution (because it produces hydroxide ions). Fluorescence microscopy is then used to observe the impact of the electrochemically generated microscale pH gradient on the cytosolic pH of cells loaded with a fluorescent pH sensor. The obtained results indicate that electrochemically induced acid stress affects the cytosolic pH of normal cells significantly faster than that of cancer cells while electrochemically induced alkaline stress appears to have very limited impact on the cytosolic pH of both cell types. In comparison to classic experiments concerning the regulation of cytosolic pH using perfusion chambers, the developed, electrochemistry-based, approach has the advantages of a better spatial and temporal resolution and elimination of the flow-induced shear stress.