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Your Next M.D. Might Be a PDA

Handheld sensors using specialized — and relatively cheap — biosensors may deliver an instant diagnosis of diseases, contaminated water and biological attacks.

Your doctor has a hunch that your respiratory infection and fever are caused by bacteria (and should be treated with antibiotics), but it might instead be a simple virus, which should be allowed to run its course.

Today, lab tests could take several days to complete, but in a couple of years a handheld device called an acoustic wave biosensor might sample a droplet of your saliva to reveal within seconds whether your doctor’s hunch was correct.

Just three of these biosensors, developed by the University of New Mexico Health Sciences Center and Sandia National Laboratories, exist at the moment. But the invention has been licensed for development, garnering enough buzz to have made R&D Magazine’s Top 100 list for 2010.

“It tells you in five seconds to two minutes whether or not there’s an infection there and what type it is,” says Dr. Richard Larson, vice president for research at the UNM health center and the sensor’s lead inventor.

Such devices could transform the practice of clinical medicine, but they could also be useful for screening blood, checking for water contamination and identifying veterinary diseases, he says.

“We have shown that it works with a whole variety of different viruses. We can detect H1N1. We can detect HIV. We can detect hepatitis B and hepatitis C, and a whole variety of bad viruses that could be used by terrorists.”

The device holds a slot for a removable dime-sized chip. Each chip, which can be manufactured for under $10 apiece, is customized to detect one of a variety of viruses and bacteria by coating a tiny electrode made from lithium tantalate with a peptide — a short polymer made of amino acids — specific to that microbe. If the suspect germ is present in a drop of urine, blood or saliva sample, it will bind with the peptide.

“It’s like a microscale,” Larson says. “It can measure the weight of a virus. So when a virus gets specifically caught on the surface of the chip by the molecule, that weight causes a sound wave to form on the chip — that’s the electronic part.”

The idea originated while Larson was exploring ways to rapidly screen new drugs, but he shifted directions when someone mailed anthrax-laden envelopes that killed five people and injured more than a dozen others in the wake of the 9/11 attacks.

“After 9/11 we thought we could build a technology for first responders, so if they went into a disaster situation and there was a white powder, they would be able to rapidly test it for anthrax,” Larson says.

“In order to get this to work, the real key was to get a set of engineers and physicists to work with a bunch of biologists and chemists.”

UNM scientists worked on developing the microbe-specific peptide coatings, while the Sandia team perfected the acoustic-wave chip technology — all with substantial funding from the Defense Intelligence Agency.

The chips are so sensitive they need only 30 viral particles to set off a signal, Larson said. Any water-based bodily fluid can be injected into the sensor’s port, he says, but suspect dry powders would first have to be mixed into a water solution to be tested.

As the defense-oriented version of the device came together, Larson says, “We decided we should apply this to medical use where it could have a broader impact and changed the platform of the sensor so we could detect viruses and bacteria that were relevant to human infection.”

One obvious application was for disaster scenarios, such as Haiti in the wake of the devastating earthquake there earlier last year, Larson said. The portable device, powered by AA batteries, could readily detect whether blood from a prospective donor was free from HIV or hepatitis-causing viruses, he says.

Provisional patents have been filed and the device has been submitted to the FDA for approval. Meanwhile, UNM has licensed the technology to Adaptive Methods, a Centreville, Va.-based firm that specializes in sensor technology, to bring the biosensor to market. Adaptive Methods said in a news release that it plans to commercialize the technology for use in the healthcare, homeland defense and military sectors.

Larson predicts the biggest market for the devices will be in medical practices where rapid infection diagnosis is important, including those specializing in respiratory infections and sexually transmitted diseases.

The one limitation of the device is that it cannot detect whether a microbe is from a drug-resistant strain — traditional lab cultures will still be required for that. Meanwhile, he envisions a future where different medical specialists would keep a unique selection of chips on hand suited to their type of practice.

Larson’s biggest headache at the moment is in sorting through the multitude of potential uses to figure out which one to focus on. “We’ll put our effort where we can have the biggest impact,” he says.