Tiny Detectors to Implant

Nanotechnology researchers have demonstrated a tiny, implantable detector that could one day allow diabetics to monitor their glucose levels continuously without having to draw a blood sample.

The work is the first application of a whole new class of biological sensors, scientists said in the Dec. 12 online edition of the journal Nature Materials.

The new sensors are based on single-walled carbon nanotubes: cylindrical molecules whose sides are formed from a lattice of carbon atoms, explained Michael Strano at the University of Illinois in Urbana-Champaign.

The idea is to exploit the nanotubes' ability to fluoresce, or glow, when illuminated by certain wavelengths of infrared light, "a region of the spectrum where human tissue and biological fluids are particularly transparent," Strano said.

To make a sensor, Strano and his collaborators first coat the nanotubes with a "molecular sheath," a one-molecule-thick layer of compounds that react strongly with a particular chemical -- in this case, glucose. Then they load the coated nanotubes into a needle-thin capillary tube that can safely be implanted into the body. The capillary keeps the nanotubes from directly touching living cells but still allows glucose to enter.

The researchers tested the glucose sensor by inserting it into a human tissue sample. Then they illuminated the sample with an infrared laser and verified that the strength of the fluorescence from the buried sensor was directly related to the glucose concentrations in the tissue.

-- LiveScience Staff

Image Credit: Michael Strano