Photo‐Driven Asymmetric Nanopore Electrode Enables Endogenous ROS Monitoring in Single Neuroimmune Cells

Reactive oxygen species (ROS) play central roles in neuroinflammatory signaling and neuroimmune function. However, quantitative detection of ROS in living neuroimmune cells remains challenging due to their low abundance and high sensitivity to electrical and chemical perturbations. While conventional nanoelectrodes can monitor ROS in cancer cells and macrophages, they require high operation potentials that may disrupt membrane integrity and redox homeostasis, limiting their use in sensitive neuroimmune cells. Here, we report a photo‐driven asymmetric nanopore electrode (PNE) that enables zero‐bias (0 mV) detection of intracellular H 2 O 2 . By integrating photo‐responsive g‐C 3 N 4 quantum dots within an asymmetric quartz nanopipette, pulsed light excitation generates an ionic photocurrent that decreases quantitatively with increasing H 2 O 2 concentration. The PNE delivers a linear detection range from 10 nM to 5 µM with a detection limit down to 10 nM. Further cellular imaging characterization confirms that this platform minimizes cellular perturbation, enabling in situ monitoring of intracellular H 2 O 2 dynamics in single microglial cells under oxidative stress stimulation. By virtue of this minimal perturbation, this study represents the first real‐time observation of a concentration‐dependent transition in ROS scavenging dynamics in single microglial cells, providing a previously inaccessible view of neuroinflammatory redox regulation under undisturbed physiological conditions.