Featured Research

from universities, journals, and other organizations

Rapid, Low-Cost DNA Testing

Date:
January 9, 2007
Source:
University of Rochester
Summary:
University of Rochester Professor Lewis Rothberg received a NYSTAR grant to continue working on a recent discovery by his group: how to rapidly test DNA to improve our health and make sure we're drinking clean water and eating uncontaminated food. Rothberg's new method can help forensics labs identify criminals, test water, and identify harmful genetic sequences in medical research. Rothberg's innovative procedure quickly and inexpensively identifies genetic sequences in any sample of DNA.

New Method for Identifying DNA Sequences: Here, the probe sequences are shown as black coils. The red circles are fluorescent tags on the ends of the black coils. Following dehybridization and annealing for approximately 1 minute, the fluorescent tags bind with a complementary sequence in a target (dark blue coil). The result is then mixed with gold nanoparticles and salt. A fluorescence measurement is made immediately. If the probe has hybridized to a sequence in the analyte, it is protected from adsorption on the gold and the fluorescence of its tag persists. If not, it adsorbs to the gold particles and the fluorescence is quenched.
Credit: Image courtesy of University of Rochester

Professor Lewis Rothberg of the University of Rochester Chemistry Department received a NYSTAR grant in August 2006 to continue working on a recent discovery by Huixiang Li, a research associate in his group: how to rapidly test DNA to improve our health and make sure we're drinking clean water and eating uncontaminated food.

In fact, his new method can be used to help forensics labs identify criminals, test ponds and pools before children swim in them, and identify harmful genetic sequences in medical research, to name only a few applications. Rothberg's innovative procedure quickly and inexpensively identifies genetic sequences in any sample of DNA.

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.

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.

Here's how Professor Rothberg's procedure is done:

Step 1. Hybridization. This takes 10 seconds and costs $0.025.

Step 2. Add gold colloid to the hybridization solution. This takes 10 seconds and costs $0.02.

Step 3. Add salt to the solution. This takes 10 seconds and costs $0.01.

Step 4. Measure photoluminescence. This takes 1 minute.

It's as simple as that, yet nobody's ever done it before. The method is so new that the University of Rochester filed patents for it in 2004 and 2006. In May 2005, Professor Rothberg created a company called Diffinity Genomics, Inc. with two partners to further study and commercialize his technique.

Professor Rothberg's method is part of a much larger process that analyzes DNA. First, a technician extracts the DNA from the blood, tissue, or food. This typically take up to an hour. Second, there is generally not enough DNA to analyze, so it must be chemically amplified. This also takes apprximately one hour. The new process comes after these two steps, saving a final hour of work for the technician, who ordinarily would be doing gel electrophoresis.

Perhaps more important than the savings in time and money, the new method works to determine single-base mutations in DNA, whereas gels cannot do this without even further processing. Professor Rothbergs concludes, "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."


Story Source:

The above story is based on materials provided by University of Rochester. Note: Materials may be edited for content and length.


Cite This Page:

University of Rochester. "Rapid, Low-Cost DNA Testing." ScienceDaily. ScienceDaily, 9 January 2007. <www.sciencedaily.com/releases/2007/01/070107210358.htm>.
University of Rochester. (2007, January 9). Rapid, Low-Cost DNA Testing. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2007/01/070107210358.htm
University of Rochester. "Rapid, Low-Cost DNA Testing." ScienceDaily. www.sciencedaily.com/releases/2007/01/070107210358.htm (accessed July 31, 2014).

Share This




More Health & Medicine News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Health Insurers' Profits Slide

Health Insurers' Profits Slide

Reuters - Business Video Online (July 30, 2014) Obamacare-related costs were said to be behind the profit plunge at Wellpoint and Humana, but Wellpoint sees the new exchanges boosting its earnings for the full year. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
At Least 20 Chikungunya Cases in New Jersey

At Least 20 Chikungunya Cases in New Jersey

AP (July 30, 2014) At least 20 New Jersey residents have tested positive for chikungunya, a mosquito-borne virus that has spread through the Caribbean. (July 30) Video provided by AP
Powered by NewsLook.com
Xtreme Eating: Your Daily Caloric Intake All On One Plate

Xtreme Eating: Your Daily Caloric Intake All On One Plate

Newsy (July 30, 2014) The Center for Science in the Public Interest released its 2014 list of single meals with whopping calorie counts. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins