Electrochemical H2O2 determinations from single living human monocytes
Hydrogen peroxide (H2O2) belongs to the reactive oxygen species (ROS). In low concentrations (nM to low µM), it displays intra- and extracellular signaling functions, mainly by oxidizing target molecules, like proteins and lipids. Likewise, yet in much higher concentrations (high µM to mM), H2O2 is employed by specialized cells to kill pathogens, like bacteria. Cellular production of H2O2 is paralleled by effective H2O2 degradation due to a multitude of enzymatic systems. Thus, balanced intracellular [H2O2] levels are obtained, guaranteeing physiological functioning of the cell. Using a scanning electrochemical microscope (SECM) and platinum ultramicroelectrodes, basal and stimulated H2O2 production and concomitant degradation from single primary human monocytes were measured in real-time and with high temporal resolution (1 Hz). Electrochemically produced signals can be quantified for each measuring point, and thus enable insight into the dynamics of [H2O2] changes over time and under different patho-/physiological conditions.