Nanowires Now Deliver

Researchers can now precisely manipulate nanowires to deliver molecules to individual cells and even to specific regions within cells (Nat. Nanotechnol., DOI: 10.1038/nnano.2010.104). Andre Levchenko, Chia-Ling Chien, and coworkers at Johns Hopkins University showed that they can control the trajectory of cytokine-loaded gold nanowires with a combination of alternating and constant electric fields. The alternating fields regulate the nanowire orientation, whereas the constant fields dictate the direction of motion. Using this method, the researchers manipulated nanowires to deliver tumor necrosis factor-α (TNFα), a biological molecule involved in cell signaling, to targeted cells. They monitored the effects of TNFα delivery by imaging the distribution of nuclear factor-κB (NF-κB), a transcription factor released in response to TNFα. In cell culture, NF-κB was activated only in cells that were in direct contact with the nanowires. The researchers also found that they could increase the cellular response by delivering multiple nanowires to a single cell. The team expects that other biologically active compounds can be delivered in the same way and that the method will be useful for a variety of biological applications.