Miniaturized lab permits saliva screening on the go

02/14/05

Tests could detect drug use, disease or bioweapons

WASHINGTON A team of scientists and engineers led by Daniel Malamud at the University of Pennsylvania has developed a robust means of analyzing oral samples. They believe their work will lead to a kit, not much bigger than a credit card, which could detect exposure to a variety of substances, from narcotics to anthrax to common bacteria and viruses. Their plan would increase ease of detection and accelerate response time whether it was used in the middle of a public health incident or in a busy doctor's office.

At a special session on saliva-based diagnostics at the Annual Meeting of the American Association for the Advancement of Science today in Washington, Malamud will present their work on creating a prototype oral swab kit that detects HIV and Bacillus cereus, a bacterium closely related to B. anthracis.

"Nearly everything that is going on in your body reveals itself in some way in the fluids in your mouth whether it is from saliva, mucous or the plaque on your teeth," said Malamud, a professor in the Department of Biochemistry at Penn's School of Dental Medicine. "Oral swabs are already a great means of detecting substances, such as drugs or alcohol, but we're looking for ways to detect and identify things, such as DNA or bacteria, that you would otherwise need a laboratory to do."

Research has shown that fluids in the mouth contain ions, drugs, bacteria, viruses, hormones, antibodies, growth factors, DNA and RNA. While some rapid saliva tests are already in use, such as alcohol and drug tests that can be performed on the spot by police, to replicate other tests, such as the presence of anthrax, would require an entire laboratory. Malamud and his colleagues are striving to, in essence, reproduce a laboratory in a small device that could be used in any setting and that would produce results in less than an hour.

One particular breakthrough was made by the laboratory of Haim Bau in Penn's School of Engineering and Applied Science in miniaturizing PCR, the technique of amplifying trace amounts of DNA or RNA to detectable levels.

"Normally, PCR involves a thermocycler device about the size of a toaster oven that heat and cools a sample through a series of reactions," Malamud said. "Bau and his wizards were able to duplicate the entire process in a loop just a few centimeters long that carries out the process in a fraction of the time."

In the device that Malamud and his colleagues are working on to detect HIV or B. cereus, a sample is taken with a small sponge. The user than would insert the swab into a small device to squeeze out the contents of the sponge. The liquid could then be analyzed through a series of reactions that could determine the presence of antibodies, antigens, RNA or DNA that correspond to bacteria or viruses.

"Such a system could make a difference when tests are needed on the scene," Malamud said. "This might be obviously necessary when it comes to a potential bioterrorism incident or an accident of exposure, but it could also make the difference in the doctor's office or emergency room, when you would need to know whether or not to administer antibiotics."

In addition to Penn's School of Dental Medicine and School of Engineering and Applied Science, this project involves participation from researchers from Leiden University in the Netherlands and OraSure Technologies Inc. in Bethlehem, Pa.

Source: Eurekalert & others

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