Ultrasmall Nanopipette: Toward Continuous Monitoring of Redox Metabolism at Subcellular Level

Ionic current rectification (ICR) based nanopipettes allow accurate monitoring of cellular behavior in single living cells. Herein, we proposed a 30 nm nanopipette functionalized with G‐quadruplex DNAzyme as an efficient biomimetic recognizer for ROS generation at subcellular level via the changes of current–voltage relationship. Taking advantages of the ultra‐small tip, the nanopipette could penetrate into a single living cell repeatedly or keep measuring for a long time without compromising the cellular functions. Coupled with precision nanopositioning system, generation of ROS in mitochondria in response to cell inflammation was determined with high spatial resolution. Meanwhile, the changes of aerobic metabolism in different cell lines under drug‐induced oxidative stress were monitored continuously. We believe that the ICR‐nanopipette could be developed as a powerful approach for the study of cellular activities via electrochemical imaging in living cells.