With contributions from Chia-Ling Chien, a professor of physics and astronomy in the Krieger School of Arts and Sciences, and Robert Cammarata, a professor of materials science and engineering in the Whiting School, the team developed nanowires coated with a molecule called tumor necrosis factor-alpha (TNF-alpha), a substance released by pathogen-gobbling macrophages, commonly called white blood cells. Under certain cellular conditions, the presence of TNF-alpha triggers cells to switch on genes that help fight infection, but TNF-alpha also is capable of blocking tumor growth and halting viral replication.
Exposure to too much TNF-alpha, however, causes an organism to go into a potentially lethal state called septic shock, Levchenko said.
Fortunately, TNF-alpha stays put once it is released from the wire to the cell surface, and because the effect of TNF-alpha is localized, the tiny bit delivered by the wire is enough to trigger the desired cellular response. Much the same thing happens when TNF-alpha is excreted by a white blood cell.
Additionally, the coating of TNF-alpha gives the nanowire a negative charge, making the wire easier to maneuver via the two perpendicular electrical fields of the "tweezer" device, a technique developed by Donglei Fan as part of her Johns Hopkins doctoral research in materials science and engineering.
"The electric tweezers were initially developed to assemble, transport and rotate nanowires in solution," Cammarata said. "Donglei then showed how to use the tweezers to produce patterned nanowire arrays as well as construct nanomotors and nano-oscillators. This new wo
|Contact: Mary Spiro|
Johns Hopkins University