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Quick and Inexpensive DNA Testing

by Monisha on  January 8, 2007 at 12:46 PM Genetics & Stem Cells News   - G J E 4
Quick and Inexpensive DNA Testing
Professor Lewis Rothberg of the University of Rochester was awarded a NYSTAR grant to resume his research on a recent discovery by one of his team members. He along with his colleagues contributed to a remarkable research. They developed cost effective methods to study DNA material in quick simple steps. This will ensure better health and clean drinking water and make sure that we eat uncontaminated food. Rothberg's novel method can even be used in several other applications like assisting forensic experts to pinpoint criminals, and in earmarking potentially dangerous genetic sequences in medical research field. Rothberg's ground breaking research paves the way to identify sequences in genotypes in any DNA sample rapidly and cost effectively.
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The technology is a novel fluorescent DNA screening assay, which rapidly determines whether specific DNA target sequences are present in an analyte. In simple terms, the analyte contains the DNA target sequences as well as other DNA sequences, and the assay filters out only the targets. Professor Rothberg's assay is based on the electrostatic properties of DNA.

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The principle underlying the method is that single-stranded DNA and double-stranded DNA have significantly different affinities for attaching to ionically charged gold nanoparticles. Because ions have electric charges, having gained or lost electrons, they attract their opposites. An anion with a negative electric charge will attract positive charges, a cation with a positive charge will attract negative charges. Single-stranded DNA adsorbs on negatively charged citrate ions on the gold nanoparticles while double-stranded DNA does not. Given that both single-stranded and double-stranded DNA are (nominally) negatively charged, this proven phenomenon intrigues the research group.

The new assay determines whether a fluorescently-tagged short probe sequence of single-stranded DNA matches a sequence in the target analyte. When it does not, the fluorescently tagged probe adsorbs on a gold nanoparticle and its fluorescence is quenched. If the probe sequence is able to hybridize to the target, it will not adsorb on the gold and its fluorescence persists.

The new method is simple and effective. It costs very little, and it's very quick.

The most widespread and common method of screening DNA is called gel electrophoresis. Each test takes 1 hour and can cost as much as $1.00. Setting up a lab for gel electrophoresis requires a capital expenditure of $5,000. By contrast, Professor Rothberg's technique only requires 5 minutes, and it costs approximately $0.05 (literally five cents) per test. The capital expenditure to set up a lab with the new technique is only $600.

Source: Eurekalert
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