Prussian blue modified carbon nanopipette for real-time voltametric monitoring of K⁺ in single living cells

Aberrant fluctuations in the concentration of cytosolic Potassium ion (K⁺), crucial players in diverse physiological processes, are pathologically implicated in multiple disease states. The real-time monitoring of intracellular K⁺ dynamics thus represents a critical capability for biomedical research. Herein, by integrating Prussian blue (PB) inside the carbon nanopipette (CNP), we developed a nanosized K + -selective electrode that exhibits a broad detection range (10⁻⁵ to 10⁻¹ M) and a low detection limit of 3.38 μM. Moreover, the real-time monitoring of the K⁺ dynamics inside single living cells was also achieved owing to the fast response of the nanoelectrode. The fabricated PB-CNP would provide a novel research tool to monitor K⁺ at the confined spaces, which could find broad applications in the area of fundamental neurobiology, cellular physiology and electrochemistry.