Unsure About Paternity? Here Comes the Cheapest, Fastest and Most Precise DNA Test...

Are you not sure about paternity?

Police investigation lasts too much?

Soon, all of these will have a cheap and quick solution.

Professor Lewis Rothberg of the University of Rochester Chemistry Department is developing a rapid DNA test. The new method could also be used to check ponds and pools before children swim in them, identify harmful genetic sequences in medical research, make sure we're drinking clean water and eating uncontaminated food and many other applications.

The new technology rapidly determines whether specific DNA target sequences are present in a probe. The analyte contains the DNA target sequences as well as others, and the method filters out only the targets. The new method is based on the difference in electrostatic properties of single-stranded DNA and double-stranded DNA for attaching to ionically charged gold nanoparticles. Ions have negative electric charges, and having gained or lost electrons, attract positive or negative opposites.

Single-stranded DNA adsorbs on citrate ions on the gold nanoparticles while double-stranded DNA does not. As both single-stranded and double-stranded DNA are negatively charged, this puzzles the researchers.

The new method determines whether a fluorescently-tagged short probe sequence of single-stranded DNA matches a sequence in the target analyte. If it is a match, the fluorescently tagged probe adsorbs on a gold nanoparticle and its fluorescence is shut down. If not, it will not adsorb on the gold and its fluorescence persists.

The new method - besides being simpler - it's also 12 times quicker (5 minutes) and 20 times cheaper ($0.05 per test) than the common DNA gel electrophoresis method.

Moreover, setting up a gel electrophoresis lab requires $5,000 while the new technique just $600.

The steps of the new approach are:
1. Hybridization, in just 10 seconds, costing $0.025.
2. Gold colloid adding to the hybridization solution, in just 10 seconds and costing $0.02.
3. Salt addition to the solution: 10 seconds and $0.01.
4. Photoluminescence measurement: 1 minute.

The method is part of a much larger process that analyzes the DNA. First, a technician extracts the DNA from the blood, tissue, or food in an hour. After that, DNA is chemically amplified, in also approximately one hour. This way, the process saves one work hour for the technician, who would be doing gel electrophoresis.

More crucial is that the new method is much more precise, determining single-based mutations in DNA, whereas gel electrophoresis cannot do this without even further processing. "This could be very important for applications in personalized medicine where a particular DNA sequence will be linked to a prescribed therapy. In fact, we see this happening already", said Rothbergs.