May 15, 2004
New DNA Testing Method Holds Promise For Clinical Use

A new DNA testing method promises to enable DNA testing in doctors' offices.

EVANSTON, Ill. --- Since the advent of the polymerase chain reaction (PCR) nearly 20 years ago, scientists have been trying to overturn this method for analyzing DNA with something better. The “holy grail” in this quest is a simple method that could be used for point-of-care medical diagnostics, such as in the doctor’s office or on the battlefield.

Now chemists at Northwestern University have set a DNA detection sensitivity record for a diagnostic method that is not based on PCR -- giving PCR a legitimate rival for the first time. Their results were published online today (April 27) by the Journal of the American Chemical Society (JACS).

“We are the first to demonstrate technology that can compete with -- and beat -- PCR in many of the relevant categories,” said Chad A. Mirkin, director of Northwestern’s Institute for Nanotechnology, who led the research team. “Nanoscience has made this possible. Our alternative method promises to bring diagnostics to places PCR is unlikely to go -- the battlefield, the post office, a Third World village, the hospital and, perhaps ultimately, the home.”

The new selective and ultra-sensitive technology, which is based on gold nanoparticles and DNA, is easier to use, considerably faster, more accurate and less expensive than PCR, making it a leading candidate for use in point-of-care diagnostics. The method, called bio-bar-code amplification (BCA), can test a small sample and quickly deliver an accurate result. BCA also can scan a sample for many different disease targets simultaneously.

The Northwestern team has demonstrated that the BCA method can detect as few as 10 DNA molecules in an entire sample in a matter of minutes, making it as sensitive as PCR. The technology is highly selective, capable of differentiating single-base mismatches and thereby reducing false positives.

As the term "polyermase chain reaction" indicates the existing test relies upon the polymerase enzyme. Enzymes break down, work best in narrow temperature ranges and are usually a pain to deal with. While some progress has been made on. While some progress has been made of late on how to stabilize enzymes they are still best avoided if the goal is to make a cheap reusable test with a long shelf-life.

Some of the DNA testing methods that will be developed use in for clinical settings will likely turn out to be amenable to further technological refinement to become simple enough for mass market consumer use as well. Once DNA testing kits become available over the counter genetic privacy will be impossible to protect.. Even fingerprints will be used as sources of DNA samples.

There are plenty of precedents for the development of home medical testing kids. Consider the blood sugar testing kits used by diabetics or the pregnancy testing kits that are advertised so widely on television. Mass market DNA testing kits will be developed because the market demand is there and as this latest report demonstrates technologies can be developed that will drive down costs and increase ease of use.

Share |      Randall Parker, 2004 May 15 03:06 PM  Biotech Advance Rates


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