Departmental Papers (MEAM)

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Sean E. Anderson and Haim H. Bau, “Electrical Detection of Cellular Penetration during Microinjection with Carbon Nanopipettes”, Nanotechnology 2014, 25, 245102


The carbon nanopipette (CNP) is comprised of a pulled-glass pipette terminating with a nanoscale (tens to hundreds of nm) diameter carbon pipe. The entire inner glass surface of the CNP is coated with a carbon film, providing an electrically conductive path from the carbon tip to the distal, macroscopic end of the pipette. The CNP can double as a nanoelectrode, enabling electrical measurements through its carbon lining, and as a nanoinjector, facilitating reagent injection through its hollow bore. With the aid of a lock-in amplifier, we measured, in real time and with millisecond resolution, variations in impedance as the CNP penetrated into the cytoplasm and nucleus of adherent human osteosarcoma (U20S) cells. The capacitance change associated with nucleus penetration was, on average, 1.5 times greater than the one associated with cell membrane penetration. The experimental data was compared and favorably agreed with theoretical predictions based on a simple electrical network model. As a proof of concept, the cytoplasm and nucleus were transfected with fluorescent tRNA, enabling real-time monitoring of tRNA trafficking across the nuclear membrane. The CNP provides a robust and reliable means to detect cell and nucleus penetration, and trigger injection, thereby enabling the automation of cell injection.


carbon nanopipette, microinjection, impedance, cell, automated



Date Posted: 15 December 2016

This document has been peer reviewed.