World's tiniest test tubes get teensiest corks







Additionally, the tubes also had to be closed at one end to form the classic test tube shape, a problem Martin and his group solved in research published in 2004.

To "cork" the test tubes in the latest research, the researchers applied an amino chemical group to the mouth of the tubes and an aldehyde chemical group to the corks. The two groups are complementary, so they bond with one another.

Billions of nanotubes could fit on a postage stamp. So, said Martin, "we don't put individual caps in each nanotube the way corking machines do for bottles."

Instead, the scientists immerse a small mesh that holds millions of amino-modified nanotubes, all precisely lined up in a grid pattern, into a solution imbued with millions of the corks. Brownian motion -- what happens when minute particles immersed in a fluid move about randomly -- takes care of the rest. The corks simply float around, then slip into the mouths of the tubes as they encounter them.

The diameter of the tubes is about 80 nanometers, or 80-billionths of a meter. Even though they are tiny, each tube can hold about 5 million drug molecules. "Each tube packs a real punch in terms of the number of drug molecules it can deliver," Martin said.

Sang Bok Lee, an assistant professor of chemistry and biochemistry at the University of Maryland, works on similar research. He said scientists have proposed capping the tubes using chemical interactions between the drugs and the tubes. But that might not work because the tube could leak before it reaches its target.

"I strongly agree that Professor Martin's proposed strategy will be one of the ideal solutions for the problem of controlling drug uptake and release," he said in an e-mail.

The UF scientists aren't there yet. There's no easy way to unlock the amino chemical group from the aldehyde chemical group. So while Martin says there are some promising possibilities, he and his colleagues have their next job cut out for them: figuring out how to uncork the tubes.


Writer: Aaron Hoover,, (352) 392-0186
Source: Charles Martin,, (352) 392-8205

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-- Carl Jung