Silicon Valley companies take aim at detecting deadly pathogens
By Brian Gaylord
02/07/2007
SANTA CLARA, CA -- A couple of Silicon Valley-based high-tech companies are developing diagnostic tools for the purpose of detecting deadly pathogens in food supplies.
NanoSensors Inc., a nanotechnology development company based here, is licensing nanoporous silicon-based biosensor technology through Michigan State University and a university in South Korea to develop food-safety analysis systems.
In addition to silicon-based filters, NanoSensors is also using carbon nanotube technology to detect and isolate biologically based pathogens. Carbon nanotubes are cylindrical carbon molecules with properties that make them potentially useful in extremely small-scale electronic and mechanical applications.
NanoSensors is working on a reusable testing kit. The disposable sensor is about the size of a quarter and has a reader for measuring data embedded in it. The sensor transmits back to an external data acquisition unit that can be used by people at all levels of the food distribution chain. Customers will be able to buy and use disposable sensors on each specific lot of produce that is tested.
NanoSensors licensed its biosensor technology in August. Its sensor can detect E. coli but cannot tell what strain it is. Depending on the host molecule, the sensor could be used to detect salmonella.
The sensor detects the DNA of the host molecule on porous silicone. The DNA of the molecule is attached to that surface; the sensor is functionalized when DNA is placed on the surface. The base of the sensor is disposable. Joshua Moser, vice president and chief operating officer of NanoSensors, said that the company "has made a tremendous amount of progress in a short amount of time."
Mr. Moser said that nano- or molecular-scaled devices operate at the same scale as the biological agents they target, which allows the technology to both detect and isolate targeted pathogens. Nanoprobes and filters can address viruses and bacteria at a level of specificity that is hard to get at with larger technology, and also can provide faster and more accurate results than existing technology, he said.
Ted Wong, chief executive officer of NanoSensors, said that the company could determine the concentration of E. coli with its sensor, which is a "first alert" of E. coli.
"We're trying to provide an economically viable solution," Dr. Wong said. "The efficiency is very high."
The sensor's testing results can be exported to a PDA or cell phone. The company soon will start third-party testing and anticipates testing its product at a water treatment plant for a few months.
"Sensors could be the first use of carbon nanotubes," Dr. Wong said. NanoSensors anticipates jumping up to the use of carbon nanotubes, which is the "next generation," he said.
NanoSensors has collected salmonella data in more than three months of testing.
Dr. Wong said that his dream is to have a sensor "that covers an array of different things."
In late December, NanoSensors announced that it had engaged a third-party contractor to manufacture units of a test version of its biosensor product that will be used for third-party field testing. The product is based on the NanoSensors nanoporous silicon-based biosensor technology to detect E. coli.
Although NanoSensors has not entered into testing agreements with third parties, it is seeking to enroll between six and 10 users in its product-testing program.
Another Silicon Valley company -- Cepheid, based in Sunnyvale, CA -- can take credit for playing a critical role in containing the outbreak of E. coli 0157:H7 detected in fresh spinach.
New Mexico's health department used a molecular diagnostic tool manufactured by Cepheid to isolate the E. coli. Researchers performed rapid molecular tests that pointed to a bag of spinach that sickened a New Mexico woman, a major breakthrough in the case.
David Persing, Cepheid's chief medical and technology officer, said that about half of all state public health labs in the nation are using the company's SmartCycler instrument. Unlike traditional culture tests that take days to generate a result, molecular diagnostics quickly and accurately identify microorganisms by identifying specific segments of DNA.
Another advantage to molecular detection is that it can detect DNA whether bacteria are alive or dead.
Mr. Persing said that the opportunity exists to catch outbreaks such as the E. coli outbreak in spinach earlier in the process, and that the goal must be to detect and intercept pathogens before they enter the general food supply. "The evolution of technology is to small sophisticated analysis," Mr. Persing said, adding that cartridges for testing bacteria are small, easy to work with and don't require a specialty lab.
He said that he favors installing Cepheid's SmartCycler instrument in fresh produce-processing plants. The price runs about $30 to $50 per cartridge. Mr. Persing anticipates similar deployment of sensor technology to include agricultural operations and food distribution centers.
