Measuring Both pH and O(2) with a Single On-Chip Sensor in Cultures of Human Pluripotent Stem Cell-Derived Cardiomyocytes to Track Induced Changes in Cellular Metabolism

[Image: see text] In vitro studies which focus on cellular metabolism can benefit from time-resolved readouts from the living cells. pH and O(2) concentration are fundamental parameters upon which cellular metabolism is often inferred. This work demonstrates a novel use of a ruthenium oxide (RuO(x)) electrode for in vitro studies. The RuO(x) electrode was characterized to measure both pH and O(2) using two different modes. When operated potentiometrically, continuous pH reading can be obtained, and O(2) concentration can be measured chronoamperometrically. In this work, we demonstrate the use of the RuO(x) electrodes in inferring two different types of metabolism of human pluripotent stem cell-derived cardiomyocytes. We also show and discuss the interpretation of the measurements into meaningful extracellular acidification rates and oxygen consumption rates of the cells. Overall, we present the RuO(x) electrode as a versatile and powerful tool in in vitro cell metabolism studies, especially in comparative settings.