Toxicity to Human Cells of Nanotubes, Nanowires Investigated

Carbon nanotube illustration (National Science Foundation)

A research team at Brown University in Providence, Rhode Island has found some nanoscale materials interact with human cells much like asbestos fibers, making the materials toxic. Their research on carbon nanotubes and gold nanowires appears online in the journal Nature Nanotechnology (paid subscription required).

The team led by Huajian Gao, professor of engineering found that the pointed shape of the nanomaterials with a rounded tip leads the cell to react to the material as if it is spherical. The cell then tries to ingest the material which, because of the oblong shape, leads to failure.

The diameter of the nanomaterials, 10 to 100 nanometers (1 nanometer equals 1 billionth of a meter), says Gao, is what fools the cell. At that diameter, the foreign materials fit into the cell’s requirements, and when encountering a nanotube, special proteins called receptors on the cell cluster and bend the membrane wall to wrap the cell around the nanotube tip.

The authors call this sequence of events “tip recognition.” As this recognition occurs, the nanotube is tipped to a 90-degree angle, which reduces the amount of energy needed for the cell to engulf the particle. Within minutes, Gao says, the cell senses it cannot fully engulf the structure, triggering an immune response that can cause repeated inflammation.

Nanomaterials like carbon nanotubes have promise in medicine, such as acting as vehicles to transport drugs to specific cells or to specific locations in the human body. If we can fully understand  these nanomaterial-cell dynamics, says Gao, “we can make other tubes that can control how cells interact with nanomaterials and not be toxic. We ultimately want to stop the attraction between the nanotip and the cell.”

Read more: Lab Tests Indicate Inhaled Carbon Nanotubes Pose Cancer Risk

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