Cells selectively absorb short nanotubes

Mar 30, 2007
Cells selectively absorb short nanotubes
Nanotube length threshold: NIST experiments using human lung cells demonstrate that DNA-wrapped single-walled carbon nanotubes longer than about 200 nanometers are excluded from cells, while shorter lengths are able to penetrate the cell interior (dark lines in the fluorescence image above). Credit: NIST

DNA-wrapped single-walled carbon nanotubes (SWCNTs) shorter than about 200 nanometers readily enter into human lung cells and so may pose an increased risk to health, according to scientists at the National Institute of Standards and Technology. The results of their laboratory studies appear in an upcoming issue of Advanced Materials.

Eyed for uses ranging from electronic displays to fuel cells to water filtration, SWCNTs are tiny cylinders—essentially single-sheet rolls of carbon atoms. They are many times stronger than steel and possess superlative thermal, optical and electronic properties, but safety and biocompatibility remain an open question.

"Published data citing in vitro (outside the body) toxicity are particularly inconsistent and widely disputed," writes biomaterials scientist Matthew Becker and his NIST colleagues. Public concerns surrounding the environmental, health and safety impacts of SWCNTs could derail efforts to fast track the development of nanotubes for advanced technology applications. A significant hurdle in outlining the parameters contributing to nanotube toxicity is to prepare well-defined and characterized nanotube samples, as they typically contain a distribution of lengths, diameters, twists and impurities.

The team chose to isolate the effects of nanotube length. They first adsorbed short DNA molecules onto the nanotubes because this renders them soluble in water and allows them to be sorted and separated by length. The researchers then exposed human lung fibroblasts to solutions containing unsorted nanotubes. Regardless of the concentration levels, the cells did not absorb between about one-fourth and one-third of the SWCNTs in the solutions. Further examination of the results revealed that only short nanotubes made it into the cellular interior.

In the next phase of the research, the team exposed the cells to sorted nanotubes of controlled length. They found that tubes longer than about 200 nanometers were excluded from the cells and remained in solution. Cells exposed to the longer nanotube solutions did not undergo a decrease in metabolic activity, but cells exposed to nanotubes below that threshold absorbed them and, depending on the concentration level, died or showed other signs of toxicity. "Our results demonstrate that cellular uptake in these lung cells depends significantly on the length of the nanotubes," Becker explains. "This is the first of many steps in the critical goal of reducing health risk by de novo engineering of the nanotubes themselves."

Citation: M.L. Becker, J.A. Fagan, N.D. Gallant, B.J. Bauer, V. Bajpai, E.K. Hobbie, S.H. Lacerda, K. B. Migler and J.P. Jakupciak. Length-dependent uptake of DNA-wrapped single-walled carbon nanotubes. Advanced Materials, published on-line : 20 March 2007.

Source: National Institute of Standards and Technology

Explore further: Researchers develop efficient method to produce nanoporous metals

add to favorites email to friend print save as pdf

Related Stories

Rare new species of plant: Stachys caroliniana

27 minutes ago

The exclusive club of explorers who have discovered a rare new species of life isn't restricted to globetrotters traveling to remote locations like the Amazon rainforests, Madagascar or the woodlands of the ...

New terahertz device could strengthen security

31 minutes ago

We are all familiar with the hassles that accompany air travel. We shuffle through long lines, remove our shoes, and carry liquids in regulation-sized tubes. And even after all the effort, we still wonder if these procedures ...

European space plane set for February launch

40 minutes ago

Europe's first-ever "space plane" will be launched on February 11 next year, rocket firm Arianespace said Friday after a three-month delay to fine-tune the mission flight plan.

Space station rarity: Two women on long-term crew

41 minutes ago

For the 21st-century spacewoman, gender is a subject often best ignored. After years of training for their first space mission, the last thing Samantha Cristoforetti and Elana Serova want to dwell on is the ...

Recommended for you

'Mind the gap' between atomically thin materials

Nov 23, 2014

In subway stations around London, the warning to "Mind the Gap" helps commuters keep from stepping into empty space as they leave the train. When it comes to engineering single-layer atomic structures, minding ...

Paper electronics could make health care more accessible

Nov 19, 2014

Flexible electronic sensors based on paper—an inexpensive material—have the potential to some day cut the price of a wide range of medical tools, from helpful robots to diagnostic tests. Scientists have ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.