Tuesday, July 31, 2007

Nano World: Edible nanotech on the horizon


NEW YORK -- Edible forms of nanotechnology could help make smart programmable drinks and more effective drugs.

If the prospect of edible nanotech sounds frightening, "it is not about carving little robots for use in food," physicist Anthony Dinsmore at the University of Massachusetts in Amherst told UPI's Nano World.

Instead, scientists are creating edible capsules only nanometers or billionths of a meter in size to enhance food or medicine. "We're creating nanoparticles that can assemble themselves and made of materials already found in foods. We're not doing any exotic chemistry," Dinsmore said of his group's work.

Edible nanoparticles can be made in a wide range of shapes, from spheres to pipes, and are composed of materials either relatively inert in the body, such as silicon or ceramics, or materials that react with the body's heat or chemistry, such as polymers. The contents that each nanoparticle lugs around can include flavorings, drugs or even fluorescent dyes.

One key advantage edible nanoparticles have over larger particles "is how nanotechnology can take something that is extremely insoluble in nature, like some drugs, and by breaking them up to the nano-level help release them in the body," said Roger Aston, strategy director of pSivida in Perth, Australia.

One surprising source for edible nanoparticles could come from the halloysite clay of the Old Dragon Mine in Utah. Long, naturally occurring ceramic nanotubes exist within the clay, said Bill Jacobson, president of Atlas Mining in Osborn, Ind.

"We have at least 300,000 tons of this clay, and we think there might be more," Jacobson told Nano World. "Probably 85 percent or 90 percent is tubular."

Atlas Mining is working with NaturalNano in Rochester, N.Y., to develop the halloysite nanotubes. "We're thinking about maybe getting the vitamin industry involved," Jacobson said.

Nanoparticles can be built so they deliver their contents exactly the way their designers wish. For instance, they can release their contents upon reaching specific targets -- growing porous upon reaching acids in the stomach, expanding when exposed to heat, or bearing molecules such as proteins that make them stick or other react with certain types of cells, such as cancerous tumors.

In terms of enhancing the nutritional quality of food, "you can imagine there are some things that you would want to deliver to, say, the intestine and not the mouth, such as fish oil," Dinsmore said. "For administering drugs to a patient, you can imagine delivering a medicine to the part of the body where it's needed most and not have to go everywhere else, so the overall dose you use is lower but the drug is used more effectively. This is clearly a way to help keep healthcare costs and side effects down -- some of the more pressing issues out there."

In addition to releasing drugs, nanoparticles could release a dye or trace chemical in the body upon making contact with proteins specific to cancer, "to let doctors know something is there," Dinsmore suggested.

Edible nanoparticles could release their contents when given a specific trigger, "such as a light stimulus," he said. "You can shine light into the body, and it will penetrate. This way doctors can activate the release of a drug at the most beneficial time from outside a patient's body using lamps."

Aside from carrying drugs with precision, nanoparticles have the capability to break open upon command, something that could lead to smart, programmable foods and drinks.

Dinsmore is a member of the NanoTek Consortium, a group of 15 universities and companies dedicated to using nanotechnology to improve the food industry. NanoteK scientists have proposed using specific frequencies of ultrasound or microwaves to pop nanoparticles containing specific aromas, flavors or dyes, so food makers could program a drink to be the color or taste desired.

Another concept under development involves nanoparticles that can stick to specific parts of the gut, something nanotech experts acknowledge could be a real challenge.

"The mouth-to-anus transit time is about 30 hours and in the place with the highest surface area, the small intestine, the residence time of small particles is often just three hours, so there's not a lot of time for absorption," said pharmaceutical scientist Patrick Sinko at Rutgers University in Piscataway, N.J.

To enhance the absorption of medicines, researchers are creating nanoparticles that can hook onto the gut and thus stay longer, increasing drug uptake. For instance, Sinko noted, the herpes drug Valtrex and the AIDS drug Retrovir hook onto nutrient transporters in the intestines, giving them higher rates of absorption.

"We know viruses get taken up in the gastrointestinal track, so we're following up on viral mechanisms to investigate," Sinko told Nano World. He said the hope is nanoparticles can double or even triple the amount of time for drug therapies to be absorbed by the body.

In general, he said, "people are starting to hope that nanotechnology can allow folks to deliver drugs that we today can't deliver orally. It would be great to take a drug that you normally have to inject and dry it, turn it to a powder, put it in a nanoparticle and have a tablet for a more convenient method that can enhance compliance (to a medical regimen) in patients."

The challenges for edible nanotechnology developers -- in terms of the substances finding widespread commercial use in food -- lies in building capsules "robust enough to stand whatever processing they go through, and will yet release the active agents whenever you eat them," said materials scientist David Weitz of Harvard University in Cambridge, Mass., a NanoteK Consortium member.

Still, edible nanotechnology should reach the market "fairly fast," Dinsmore said. "We're talking about pretty simple and scalable techniques that can maybe be done at large scales without changing too much around. The big issue for new applications in food is that the cost always has to be really low -- so that excludes robots."

The future of edible nanotechnology could be silicon, Aston suggested. His firm makes nanoparticles of honeycombed silicon, with each cell of the honeycomb filled with drugs that leak out as the silicon dissolves in the body to become silicic acid, a dietary form of silicon found in foods such as beer, rice and wine.

Unlike nanoparticles made of polymers, he noted, silicon does not need exotic chemical bonds to hold each nanoparticle's contents in place, bonds that conceivably could alter the content's properties.

"With this silicon, the contents are just held there physically," Aston told Nano World.

Carefully engineering a honeycomb's thickness and pore size will allow it to dissolve on cue, Aston explained, The edible silicon made by pSivida "has the capability of holding processors, so you could program chips in foodstuffs like you would computers or air conditioners."

Aston said the company has submitted its honeycombed silicon to the U.S. Food and Drug Administration for approval.

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