Fabricated by growing and then etching a carbon film on the inside of a quartz capillary, the versatile CNPs have attracted interest worldwide since hitting the headlines earlier this year.

The pipette's carbon tip is transparent to electrons and several groups are already using the team's devices as sample holders for electron microscopy and X-ray imaging. Now, the developers have shown that their CNPs are well-suited for studying cell behaviour.

In their latest work, the researchers have injected calcium-mobilizing messengers into GPR30-positive breast cancer cells to identify signalling pathways. The group observes that its nanopipette doesn't appear to cause any lasting damage to the cells under investigation.

During the study, the team discovered several benefits of its new technology compared with traditional glass injectors. Being much less prone to breakage and clogging than glass pipettes, a single CNP was able to inject many cells before failure. The CNPs were also more visible under light microscopy thanks to their darker colour, which made it much easier to accurately position the tip in relation to the cell.

Multifunctional probe
Although pleased with their results so far, the researchers feel that the best is yet to come. A unique property of CNPs is the existence of an electrically conductive, interior carbon film running the entire length of the quartz pipette.

"Our main near-term objective is to use the conductivity of the carbon to measure electrical signals before, during and after injection," Haim Bau of the University of Pennsylvania told nanotechweb.org. "Our collaborators at Penn have also developed various chemistries to functionalize the carbon tips so that we can decorate the probes with proteins, oligonucleotides and gold particles."

For a full list of the institutions involved in the work, see links.

The researchers presented their work in Nanotechnology.