Carbon Nanotubes: Cells Bite Off More than They Can Chew
Agnes B. Kane, MD, Ph.D.
NIEHS Grant R01ES016178
NIEHS-supported researchers at Brown University report in a recent issue of Nature Nanotechnology the mechanics of how cells begin to engulf carbon nanotubes only to discover too late their cause is doomed. Carbon nanotubes that are closed on one end appear like spheres to the cells. The cells begin to engulf the rounded end and often orient the nanotube so that it is perpendicular to the cell membrane. As the nanotube brushes up against the membrane, special receptors send signals causing the cell to wrap its membrane around the nanotube. As this occurs the nanotube is tipped to a 90 degree angle, effectively reducing the amount of energy needed for the cell to engulf what it senses is a small particle.
Once the engulfing process begins, there is no corresponding signal to stop and reverse the process. Within minutes the cell senses it will not be able to completely engulf the nanotube. After that an immune response is mounted that can result in chronic inflammation. This process is very similar to the reaction of cells to asbestos fibers.
Carbon nanotubes have been touted to have a variety of uses in material science because of their high strength to weight characteristics, but also in medicine as targeted drug delivery devices. This research is important for scientists to fully understand how cells and nanomaterials interact so that they can design nanostructures that will help instead of causing harm. The team will continue this line of research with nanotubes with blunt ends or nanoribbons to determine if these structures are less harmful to cells.
Citation: Shi X, von dem Bussche A, Hurt RH, Kane AB, Gao H. Cell entry of one-dimensional nanomaterials occurs by tip recognition and rotation. Nat Nanotechnol. 2011 Sep 18. doi: 10.1038/nnano.2011.151.
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