Simultaneous Electrochemical Detection of Primary Reactive Oxygen and Nitrogen Species Released by Cell Populations in Integrated Microdevices

Innovative microdevices were designed to monitor electrochemically primary reactive oxygen (ROS) and reactive nitrogen species (RNS) released by populations of aerobic cells. Taking advantage of the space confinement and microelectrodes performances, only few experiments were sufficient to provide significant statistical data relative to the average behavior of cells during oxidative stress bursts. Platinum-black coated platinum (Pt/Pt-black) electrodes were microfabricated and optimized to achieve optimal performance during the electrochemical detection of four primary species H2O2, NO, ONOO- and NO2-.1,2 The results demonstrated that relative ROS/RNS contents in synthetic mixtures can be easily assessed at selected detection potentials. Under given experimental conditions, the Pt/Pt-black electrodes allow detection limits down to 10 nM with high sensitivities and long-term stability of the electrodes responses. The electrochemical detection of ROS/RNS released by cell populations was then implemented in a multi-chambers microsystem3 and in a microfluidics device.4 As an important cell type, RAW 264.7 macrophages secretion triggered by a calcium ionophore was chosen for assessing the performance, sensitivity and specificity of the detection in both cases. In comparison to some previous evaluations obtained from single-cell measurements, reproducible and relevant determinations could be achieved. However, separating emitting cells from the detection area in the microfluidic device seems to be a better approach to avoid any perturbations of cell behaviors by electrode operations. Furthermore, any biological effects during oxidative stress of living cells can be easily investigated. As a proof of concept, we reported the analysis of the influence of a NO synthase inhibitor during the perfusion culture.