June 15, 2008
Nanoglassblowing For Biological Nanodevices

To develop treatments that will turn back the aging clock and make our bodies young again we need more powerful tools. Given the right tools aging is a curable disease. The development of nanotechnology is the most powerful trend underway that will bring aging reversal within our reach. With that thought in mind a new development in "nanoglassblowing" provides a new way to create more powerful devices for manipulating cells and biological molecules.

While the results may not rival the artistry of glassblowers in Europe and Latin America, researchers at the National Institute of Standards and Technology (NIST) and Cornell University have found beauty in a new fabrication technique called "nanoglassblowing" that creates nanoscale (billionth of a meter) fluidic devices used to isolate and study single molecules in solution—including individual DNA strands. The novel method is described in a paper posted online next week in the journal Nanotechnology.*

Traditionally, glass micro- and nanofluidic devices are fabricated by etching tiny channels into a glass wafer with the same lithographic procedures used to manufacture circuit patterns on semiconductor computer chips. The planar (flat-edged) rectangular canals are topped with a glass cover that is annealed (heated until it bonds permanently) into place. About a year ago, the authors of the Nanotechnology paper observed that in some cases, the heat of the annealing furnace caused air trapped in the channel to expand the glass cover into a curved shape, much like glassblowers use heated air to add roundness to their work. The researchers looked for ways to exploit this phenomenon and learned that they could easily control the amount of "blowing out" that occurred over several orders of magnitude.

Nanodevices might seem boring. Research on them does not produce immediately usable dietary advice, medical treatments, or even investment advice. But nanotechnology is going to become the great enabler for the development of medical treatments and methods of human enhancement. Nanotechnology for biology is following the same pattern that we've seen in the development of computer chips which keep getting smaller, cheaper, and more powerful.

To manipulate biological molecules with precision and control the devices that manipulate them must operate at the small scale of individual biological molecules. The size of these nanochannels comes close to the size of DNA.

As a result, the researchers were able to create devices with "funnels" many micrometers wide and about a micrometer deep that tapered down to nanochannels with depths as shallow as 7 nanometers—approximately 1,000 times smaller in diameter than a red blood cell. The nanoglassblown chambers soon showed distinct advantages over their planar predecessors.

To put that 7 nanometers in perspective, the DNA double helix is about 2.4 nanometers across. So a 7 nanometer channel is almost 3 times bigger than the DNA that would need to pass thru if this technology gets used to create DNA testing devices.

This technology makes it easier to create funnels that can guide DNA and other biological molecules into the small channels.

"In the past, for example, it was difficult to get single strands of DNA into a nanofluidic device for study because DNA in solution balls up and tends to bounce off the sharp edges of planar channels with depths smaller than the ball," says Cornell's Elizabeth Strychalski. "The gradually dwindling size of the funnel-shaped entrance to our channel stretches the DNA out as it flows in with less resistance, making it easier to assess the properties of the DNA," adds NIST's Samuel Stavis.

The technology can be used to manipulate whole cells or individual molecules.

Future nanoglassblown devices, the researchers say, could be fabricated to help sort DNA strands of different sizes or as part of a device to identify the base-pair components of single strands. Other potential applications of the technique include the manufacture of optofluidic elements—lenses or waveguides that could change how light is moved around a microchip—and rounded chambers in which single cells could be confined and held for culturing.

Share |      Randall Parker, 2008 June 15 12:42 PM  Nanotech for Biotech

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