It's just sugar, right? Candy -- kids' stuff. Well, don't be too sure. In the hands of top engineers and scientists, ordinary sugar is doing some extraordinary things.
Circus Candy Inspires a Medical Miracle
Talk about sweet science; medical researchers are building artificial body parts using (believe it or not) cotton candy. If you've ever eaten it, you know how tangled (and sticky!) cotton candy can be. Those traits come via some surprising science. Cotton candy is made from almost pure sugar. Inside a cotton candy machine, that sugar is first melted into a liquid, and then fed into a strainer covered with very tiny holes. As the strainer spins, the liquid sugar sprays out as fine, hot jets. These solidify almost instantly, on hitting the cooler air. The sugar is still just sugar, but its physical form has been transformed. Instead of being crystals (orderly arrangements of molecules), the spinning and cooling turns the sugar into what scientists call an amorphous solid -- jumbles of oddly packed molecules. That's why cotton candy sticks to itself (and your hands and face!). Each strand is really a nanofiber, just three thousandths of an inch across. It turns out that this intricate tangle is an almost exact copy of the way many kinds of cells in the human body arrange themselves. For example, under a microscope, cotton candy looks amazingly like networks of capillaries (fine blood vessels). This prompted researchers at New York-Presbyterian Hospital/Weill Cornell Medical Center to try using real cotton candy as a "form" for building artificial blood vessels. To test this, they poured polymer (plastic resin) over the candy strands. Then they melted the trapped candy with hot water (much the way cotton candy melts in your mouth!). What was left was a mold filled with tiny, intermeshing channels, just like blood vessels. Now scientists are developing biodegradable plastic, which can be formed into artificial skin for burn victims. When perfected, the cotton-candy process could be used to enhance the artificial skin with delicate blood vessels that could be attached to a patient's natural ones. Scientists at Purdue University are also using this cotton-candy approach to construct artificial nerve networks. Even P.T. Barnum couldn't top that.
Will tomorrow's bionic organs run on the energy from the sugar in your blood? As it happens, your natural organs (heart, lungs, brain) already work on sugar power. Molecules of glucose (derived from the food you eat) are transported by your blood to your organs. This provides the cells there with the energy they need. Biologists call this process cell respiration. It's what keeps cells alive. By contrast, artificial hearts (and other replacement organs) usually run on electricity, which is provided by batteries. To accomplish this, experts have developed batteries with remarkable lifespans and reliability. Still, what if tomorrow's artificial heart could run on the sugar in a patient's own blood instead? Attempting to make this happen, researchers are experimenting with fuel cells -- devices that convert chemical energy directly into an electrical charge. Unlike batteries (which must be replaced or recharged), fuel cells keep working simply by adding more fuel. NASA already uses fuel cells to power some of its deep space probes. However, these fuel cells are powered by exotic fuels such as hydrogen. By contrast, "bio" fuel cells would run on glucose (blood sugar). Like cell respiration, these cells combine the sugar with oxygen, to release energy. However, the chemical process they use is very different. It depends on complex enzymes, which act as the electrodes (plus and minus terminals) of the fuel cell. Since the cell must be implanted in the body, its parts are made from nonreacting materials, including platinum. In laboratory tests by a team at Joseph Fourier University in France, the new sugar cells have generated about half the current needed to operate a...
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