Recent advances in nanopipette-based sensors for the electrochemical detection of intracellular inorganic ions

This review discusses recent advancements in potentiometric, faradaic and iontronic sensors for detecting inorganic ions at the single-cell level, focusing on the last 20 years. Despite the promising emergence of new designs for this sort of nanopipette-based electrochemical sensors, key challenges remain in achieving selective, reversible detection with quick responses, stable readouts, and minimal invasiveness. Standardized protocols for evaluating sensor performance and multimodal validation approaches, such as combining electrochemical detection with fluorescence microscopy, are crucial for advancing the field. Also, this review highlights the need for increasing throughput and automated measurements to capture cell-to-cell variability. Expanding the range of detectable analytes, including anions and trace elements, and developing multiplexed sensing capabilities are key future directions. Addressing these challenges will unlock the full potential of nanopipette-based electrochemical sensors for single-cell analysis, providing transformative insights into cellular processes for both fundamental research and clinical applications.