PORTLAND, Ore. Rensselaer Polytechnic Institute researchers have developed a way to seek out harmful proteinssuch as anthrax toxin or even cancer cellsand render them harmless by coating nanotubes with a peptide that attracts the proteins and then exposing them to light.
The work adds to the potential applications for carbon nanotubes, which have already proved applicable in semiconductors, as transistor channels; in field-emission displays; in touchscreens; in heat sinks; and as the foundation for a lightweight material that's as thin as cellophane but as strong as steel.
The technique first applies a transparent coating to the nanotubes. Peptides that attract anthrax bacteria were used in Rensselaer's initial tests, but other bacteria or even cancer cells could be targeted by specially tailored peptides, the researchers said.
Once the nanotubes and anthrax were attached to each other in the Rensselaer experiment, the researchers merely exposed the nanotubes to near-infrared light, which released free radicals that killed the anthrax.
"Shining light on carbon nanotubes results in the production of reactive oxygen species [that] kill any bacteria that have attached to them," said team leader Ravi Kane, a biochemical engineering professor.
The researchers claim the technique could be used to destroy cancer cells without affecting the surrounding tissue, because normal cells will not stick to the peptide coating. The researchers also plan to develop antibacterial coatings that can be cleaned of toxins by exposing them to near-IR light of 700 to 1,100 nanometers in wavelength.
Since the approach also works with visible-light exposure (though it takes longer under such conditions), the coatings could also be applied to common surfacessuch as handrails, countertops and doorknobsthat are breeding grounds for bacteria. "These transparent coatings could be used on nearly any surface that might be exposed to harmful contaminants," Kane said.
Joining Kane on the project were Theodorian Borca-Tasciuc, a professor in Rensselaer's department of mechanical, aerospace and nuclear engineering; postdoctoral researcher Supriya Punyani; and doctoral candidates Amit Joshi and Shyam Sundhar Bale.
Funding was provided by the National Institutes of Health and the National Science Foundation.