Scientist study ice cube trays for clues to shape medicines
Scripps Howard News Service
Must credit The News and Observer of Raleigh, N.C.
By KERSTIN NORDSTROM
Raleigh News and Observer
If you've been to a housewares store recently, you've seen them, and may have been tempted. They are those colorful silicone ice cube trays that make cubes shaped liked hearts, stars or even the Titanic.
Now, tiny versions of these trays are being used to make advances in medicine.
The DeSimone lab at the University of North Carolina-Chapel Hill uses techniques from the computer industry to make these ice cube trays, or molds. While scientists have mostly focused on the chemistry of new medicines, the DeSimone lab believes the shape of a drug is just as important.
The lab, run by Joe DeSimone, a chemistry professor at UNC with a joint appointment at North Carolina State University, has produced promising results in artificial blood, cancer treatments and vaccines.
The technology that makes it all possible is called PRINT.
To build circuits, the simplest thing the computer industry does is screen-print a metal onto a chip, resulting in what looks like a painted maze of wires. But the industry has become more sophisticated and now etches trenches into silicon chips and fills them with metal, creating wires that are flush with the surface.
PRINT uses the same techniques but makes little cups instead of trenches -- the shape and size of the particles scientists want to make -- typically about one-thousandth of a millimeter.
They fill in the molds with the chemical they want, solidify the material, and remove the particles like so many ice cubes.
PRINT can create particles that are the same size, shape and squishiness as human red blood cells. Human red blood cells are soft and malleable, allowing them to squeeze through tiny capillaries. Matching the mechanics lets the particles move through the body in the same way. In a recent paper, the group demonstrated that these particles can circulate through mice.
PRINT allows scientists to make trillions of artificial cells easily. Our bodies have 20 million to 30 million red blood cells in circulation.
The particles can be filled like jelly donuts with hemoglobin, and so can mimic the oxygen-transporting properties of real blood cells.
"If we can pull it off, then you have blood that doesn't have to be stored in a special way," allowing for warm storage and an indefinite shelf life, DeSimone said. Drawn blood is typically thrown away every 40 days. "It's guaranteed free of diseases, like hepatitis," he said.
Vaccines are another area where size, chemistry and shape can all have an impact. Viruses and bacteria have natural shapes; 90 percent of bacteria are rod-shaped, for instance. Part of our immune response is to the shape, but typical vaccine technologies have focused on the chemistry.
DeSimone describes the lab's approach as building wax models of a virus or bacteria using PRINT, then decorating the surface with the same chemical cues. The combination of shape, size and surface chemistry should be enough to trigger an immune response like a vaccine.
Liquidia, DeSimone's spinoff company, has clinically tested a flu vaccine that outperformed the commercially available vaccine by more than ten-fold. The vaccine is in the FDA pipeline, and Liquidia is working on other diseases such as malaria and dengue fever.
(Contact reporter Kerstin Nordstrom at knordstrom(at)newsobserver.com)
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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