July 10, 2003 NEW YORK – July 9, 2003 -- Researchers from Cornell University have developed a miniaturized DNA-based biological testing system that fits on a silicon chip and can be customized to detect a wide variety of microorganisms. They present their research today at the American Society for Microbiology's (ASM) Conference on Bio- Micro- Nano-systems.
The chip consists of two areas. The first area captures the DNA from the sample and purifies it. The second is a reaction chamber where a process called polymerase chain reaction is performed to rapidly replicate the selected segment of DNA, which can then be tested.
"Other people have developed real-time PCR on silicon chips, but nobody has really done the purification of the DNA sample on the same chip," says Nathan Cady, one of the researchers on the study. "As near as we can tell, we are one of the first groups to incorporate the purification step into the chip."
Cady and his colleagues are currently working on incorporating a 3rd step to the process that uses fluorescence technology where an added dye would glow green to, indicate a positive sample.
The chip itself is 2 cm x 4 cm in size. Because PCR requires a precise series of specific temperatures at specific times, it fits into a tiny device (5 cm x 5 cm x 3 cm) that handles the cycling of the temperature. Once they have finally incorporated the fluorescence, Cady expects they will have a device roughly the size of a shoebox that will be capable of real-time automated detection of biological agents.
"Part of the reason we put these functions on a chip is that it simplifies the process," says Cady. "You can hand this to someone in the field, someone who is not a trained lab technician, and they can do it."
Another advantage of this system is that it has a very broad range in what organisms it can be used to detect. That makes it very useful for a variety of purposes from monitoring food and water supplies to detecting agents of biological warfare.
"We can detect pretty much any organism as long as we have the PCR primers for it," says Cady.
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