Confined Nanopipette Sensing: From Single Molecules, Single Nanoparticles, to Single Cells

: Nanopipettes provide a promising confined space that enables advances in electrochemical, optical, and mass spectrometric measurements at the nanoscale. They have been employed to reveal the hidden population properties and dynamics of single molecules and single particles. Moreover, new detection mechanisms based on nanopipettes have led to detailed information on single cells at high spatial and temporal resolution. In this Minireview, we focus on the fabrication and characterization of nanopipettes, summarize their wide applications for the analysis of single entities, and conclude with an outlook for advanced practical sensing.