Thursday, October 13, 2005

Humor me.

But the question is, what is the significance of detection?

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Find the Protein in the Haystack

By Sam Jaffe

Story location: http://www.wired.com/news/medtech/0,1286,68887,00.html

02:00 AM Oct. 13, 2005 PT

The field of nanotechnology has been long on hype and short on real products -- with the possible exception of stain-free pants. Likewise, the emergence of personalized medicine -- that utopian vision of detecting a disease at the doctor's office before symptoms have hit, and then treating it at the molecular level -- has long been foretold, but still hasn't arrived.

But a product that should appear next year could fulfill both visions. Northbrook, Illinois-based Nanosphere is preparing to launch a diagnostic system that uses nanoparticles to detect various proteins at a level of sensitivity never before seen.

Scientists know that a protein called prostate-specific antigen, or PSA, is linked with some forms of breast and ovarian cancer. But levels of PSA are so low in women that they're impossible to detect with existing technology. Nanosphere researchers say their technology can do the trick.

"In the end, molecular biology is about amplification," said Northwestern University nanotechnologist Chad Mirkin, who is a co-founder of the company and sits on its board of directors. "If you can amplify a signal that's happening on the cellular level to the point where you can detect it at the human level, you can do great science." The Nanosphere system increases the sensitivity for detecting recognized proteins by six orders of magnitude. "Nobody else can get close to that," Mirkin said.

Nanosphere hopes to have a PSA screen ready by next year for breast and ovarian cancer as well as prostate cancer. Doctors now test for PSA in men using the ELISA protein assay, which costs hundreds of dollars per test and requires high concentrations of the protein to be successful.

"We'll be ready to sell these devices on a mass-production level by next year," said William Moffitt, Nanosphere's president and CEO. "We've established the science of how this works. Now we're just tackling engineering issues."

Mirkin originally created the system with a Department of Defense grant to create a better sensor for bioweapons. He quickly realized that his tool could do for proteins what polymerase chain reaction, or PCR, did for genetics in the '80s. PCR creates multiple copies of DNA so scientists can read very small amounts.

At the heart of Nanosphere's unique system are silver-coated nanoballs. Each ball is attached to a synthetic probe designed to bind with a specific protein. If a patient sample contains the protein of interest (for example, a protein linked to a particular type of cancer), it will be sandwiched by the silver nanoparticle and a larger, magnetized metal ball.

A magnet then removes the metal balls, carrying the target proteins and the highly reflective silver spheres along with it. Light reflected from the sample reveals the concentration of the target protein in the patient, even if only a few molecules are present in the sample.

Several emerging companies are trying to create amplification technologies based on quantum dots, another nanotechnology that causes fluorescence in the presence of specific proteins. But those companies aren't yet at the point of considering a mass-market product. Another startup, called Nanoplex Technologies, is also developing a system using metallic nanospheres for protein and nucleic-acid detection, but it is concentrating on the scientific research market, not clinical diagnostics.

If all goes as planned, Nanosphere will introduce its technology next year along with some basic protein assays that the company hopes will be attractive to hospital core-testing facilities, including tests for Alzheimer's, various cancer screens and possibly a test that can detect bovine spongiform encephalitis prions, which cause mad cow disease.

Not everyone sees an easy path for Nanosphere. The technology will have to be significantly simplified to be useful in a doctor's office, said Harri Härmä, a nanoparticle expert at the University of Turku in Finland.

"Fewer steps are desired," he said. "Nanosphere's technology involves multiple steps." Härmä added that if Nanosphere's analysis equipment can really reduce the user steps through integration without compromising accuracy, precision, time and sensitivity, the product should be well-received.

Others are more optimistic about the near-term success of Nanosphere's technology. Dale Huber, a researcher at Sandia National Laboratories who also works on protein-diagnostic nanotechnologies, sees Nanosphere's device as a landmark technology.

"This could really be the breakthrough technology that revolutionizes the medical field," he said. "Often, discoveries lead to technologies in search of a use. But in this case, the need for this type of technology is so intense that if it works as advertised, it will be hugely popular."

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