Recent advances of electrochemical sensors for detecting and monitoring ROS/RNS

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are prominent metabolic products which show well-established significance. At relatively low concentrations, they play multifaceted roles in regulating a number of physiological processes. Overproduction of ROS/RNS contributes to the pathogenesis of a plethora of physiological disorders, including but not limited to cardiovascular diseases, neurodegenerative diseases, cancer. Electrochemistry have been extensively used for detecting and monitoring ROS/RNS, benefiting from their inherent advantages including fast response, low costs, real-time detection, high sensitivity and selectivity. This review focuses on three types of ROS/RNS (H₂O₂, O₂^-, NO) with emphasis on their electrochemical detection/monitoring respectively. We demonstrate the application of electrochemical strategies for ROS/RNS detection in body fluids, in vitro, and in vivo, outlining the hardware architecture and comparing analytical performance of these sensors. This review aims for a holistic view of limitations in existing ROS/RNS detection by comprehensively explaining the shortcomings of the current works in the hope of drawing attentions to the challenges of ROS/RNS electrochemical technologies. We pay particular attention to in vitro and in vivo sensors and extend our evaluation to suggest possible solutions. Specifically, this review focuses on the development of currently nanotechnologies, biomimetic engineering, 3D-culture methods and implanted sensors to provide a guideline for future works.