In Vitro Electrochemical Detection of Hydrogen Peroxide in Activated Macrophages via a Platinum Microelectrode Array

Oxidative stress, an excess of endogenous or exogenous reactive oxygen species (ROS) in the human body, is closely aligned with inflammatory responses. ROS such as hydrogen peroxide (H₂O₂), superoxide, and radical hydroxyl ions serve essential functions in fighting infection; however, chronic elevation of these species irreversibly damages cellular components. Given the central role of inflammation in a variety of diseases, including Alzheimer's disease and rheumatoid arthritis, a low-cost, extracellular, non-invasive assay of H₂O₂ measurement is needed. This work reports the use of a platinum microelectrode array (Pt MEA)-based ceramic probe to detect time- and concentration-dependent variations in H₂O₂ production by activated RAW 264.7 macrophages. First, these cells were activated by lipopolysaccharide (LPS) to induce oxidative stress. Chronoamperometry was then employed to detect the quantity of H₂O₂ released by cells at various time intervals up to 48 h. The most stimulatory concentration of LPS was identified. Further experiments assessed the anti-inflammatory effect of dexamethasone (Dex), a commonly prescribed steroid medication. As expected, the probe detected significantly increased H₂O₂ production by LPS-doped macrophages, subsequently diminishing the pro-inflammatory effect in LPS-doped cells treated with Dex. These results strongly support the use of this probe as a non-invasive, robust, point-of-care test of inflammation, with a high potential for multiplexing in further studies.