Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Novel Nanoscale Detection of Real-Time DNA Amplification Holds Promise for Diagnostics

16.09.2016

Research team led by Nagoya University develop a label-free method for detecting DNA amplification in real time based on refractive index changes in diffracted light.

Polymerase chain reaction (PCR) is a simple and ubiquitous method in molecular biology for amplifying DNA segments into millions of copies. This is important not only for basic research, but also in diagnostics, forensics, and medical applications.


A photo and a schematic illustration for a nanofluidic diffraction grating. Label-free signals based on a diffraction intensity change were attributed to amplification of DNA molecules, such as human papillomavirus and tubercle bacilli.

Copyright : Takao Yasui

Quantitative real-time PCR is a modified version that incorporates fluorescence labeling to cumulatively measure DNA amplification, rather than monitoring it at the end of the process, as in conventional PCR. Real-time PCR therefore enables sensitive quantification of the amount of the initial DNA template. However, current techniques may introduce bias through sequence errors, pipetting inaccuracies, or unequal binding of fluorescent probes (hybridization).

A research team centered on Nagoya University has now developed a novel method of measuring real-time DNA amplification that is label-free, thus avoiding the bias issues associated with other procedures. The research and its outcomes were reported in Scientific Reports.

Existing label-free detection systems rely on surface immobilization of target molecules, which is expensive, laborious, and ineffective over time. This new method also introduces an element of hybridization bias because of complementary probe binding.

The new technique instead detects changes in the intensity of diffracted light from a laser beam passing through miniscule 200 nm (0.0002 mm)-wide nanochannels filled with analytical sample liquids. The 532-nm laser beam is focused by a lens and then diffracted by passing through the nanochannel and detected by a photodiode. Silica substrates were used to make the nanochannels, and the larger the difference between refractive indices of sample liquids and silica, the smaller is the change in diffracted light intensity, and vice versa.

“We used this technique to provide the first label-free detection of human papillomavirus and the bacteria responsible for tuberculosis,” first author Takao Yasui says. “The method is highly sensitive, and allows quantification of a wide range of initial DNA concentrations, from 1 fM to 1 pM (a 1,000-fold range), so is superior to existing fluorescence-based detection systems.”

“Our system also measures DNA amplification at the relatively low temperature of 34°C and without the need for thermal cycles,” coauthor Noritada Kaji says. “Because it has the potential to be constructed as a single chip and can detect sample volumes as small as 1 µl, which is 100–1,000 times less than conventional detectors are capable of, it is particularly suited to development as a miniaturized form of diagnostics and microbe detection.”

The article, “Label-free detection of real-time DNA amplification using a nanofluidic diffraction grating” was published in Scientific Reports at DOI:10.1038/srep31642

Journal information

Scientific Reports

Funding information

This research was supported by the Cabinet Office, Government of Japan and the Japan Society for the Promotion of Science (JSPS) through the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program), Nanotechnology Platform Program (Molecule and Material Synthesis) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, the JSPS Grant-in-Aid for JSPS Fellows, the JSPS Institutional Program for Young Researcher Overseas Visits, the JSPS Grant-in-Aid for Young Scientists (B) 25790028, a Grant-in-Aid (No. 15H01599) for Scientific Research on Innovative Areas “Innovative Materials Engineering Based on Biological Diversity” from MEXT, the Asahi Glass Foundation, and PRESTO, Japan Science and Technology Agency (JST).

Koomi Sung | Research SEA

Further reports about: DNA Diagnostics hybridization laser beam liquids nanochannels

More articles from Life Sciences:

nachricht High-Speed Locomotion Neurons Found in the Brainstem
24.10.2017 | Universität Basel

nachricht Antibiotic resistance: a strain of multidrug-resistant Escherichia coli is on the rise
24.10.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Single nanoparticle mapping paves the way for better nanotechnology

24.10.2017 | Physics and Astronomy

A quantum spin liquid

24.10.2017 | Physics and Astronomy

Antibiotic resistance: a strain of multidrug-resistant Escherichia coli is on the rise

24.10.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>