Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Uncovering Pathogens Outside the Lab

12.02.2013
DNAzymes and gold nanoparticles: a colorimetric assay for diagnostics in the field

Infectious diseases such as malaria and syphilis can be diagnosed rapidly and reliably in the field by using a simple test developed by Canadian scientists. The test is based on the use of DNAzymes and gold nanoparticles. As the researchers report in the journal Angewandte Chemie, their test allows for the sensitive detection of bacteria, viruses, and parasites.

Dangerous infectious diseases must be identified in time in order to prevent them from spreading. The DNA of pathogens is an ideal biomarker and can easily be identified by PCR. However, this is only possible if expensive laboratory equipment and trained personnel are on hand. This may not be the case in remote locations or developing nations. Alternative methods that are simple and inexpensive while also remaining sensitive and specific are needed.

Kyryl Zagorovsky and Warren C.W. Chan at the University of Toronto (Canada) have now combined two modern technologies in a novel way: They have used DNAzymes as signal amplifiers and gold nanoparticles for detection. Gold nanoparticles (GNPs) absorb light. The wavelength of the light absorbed depends on whether the nanoparticles are separate or aggregated. The difference in color can be seen with the naked eye. A solution of individual particles appears red, whereas aggregates are blue-violet in color.

DNAzymes are synthetic DNA molecules that can enzymatically split other nucleic acid molecules. The researchers separated a DNAzyme into two inactive halves that both selectively bind to a specific gene segment of the pathogen to be detected. The act of binding reunites the halves and activates them.

For their test procedure, the scientists produced two sets of GNPs that bind to two different types of DNA strand, type A and type B. In addition, they synthesized a three-part “linker” made of DNA. One end of the linker is the complement to type A DNA; the second end is the complement to type B DNA. The center part is designed to be split by active DNAzymes.

In the test sample with no pathogen present, the DNAzymes remain inactive and the linkers remain intact. They bind to a GNP at each end and link the GNPs into larger aggregates, causing the solution to turn blue-violet. In contrast, if there is pathogen in the sample, the DNAzymes are activated and proceed to split the linkers. Now only the bridging parts of the linker can bind to DNA strands of the GNPs, so they cannot link the GNPs together. The solution stays red. Because every activated DNAzyme splits many linkers, it amplifies the signal.

This new type of test is simple and inexpensive; it can be made to detect every kind of pathogen, as the researchers demonstrated by detecting gonorrhea, syphilis, malaria, and hepatitis B. In a freeze-dried state, the reagents can be stored with no problem – an important requirement for use in the field.

For the full article see https://www.wiley-vch.de/vch/journals/2001/journalist/201305pre.pdf (editorial use only).

About the Author
Dr. Warren Chan is a professor at the University of Toronto in the Institute of Biomaterials and Biomedical Engineering with affiliation with the Donnelly Center for Cellular and Biomolecular Research, and Department of Materials Science and Engineering, Chemistry, and Chemical Engineering. His research interest is in the development of nanotechnology for detecting cancer and infectious diseases. He is also the Canadian Research Chair in Nanomedicine.

Author: Warren C. W. Chan, University of Toronto (Canada), http://ibbme.utoronto.ca/faculty/core/chan.htm

Title: A Plasmonic DNAzyme Strategy for Point-of-Care Genetic Detection of Infectious Pathogens

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201208715

Warren C. W. Chan | Angewandte Chemie
Further information:
http://pressroom.angewandte.org
http://ibbme.utoronto.ca/faculty/core/chan.htm

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>