Our ability to detect pathogens has become quite good, but it usually requires complex laboratory techniques. Sometimes we need a quick result, or there is no laboratory nearby.
Portable and fast methods of detection that are also sensitive, reliable, quantitative, and effective over a broad range of concentrations are thus highly desirable. In the journal Angewandte Chemie, American researchers have now introduced a new approach for a lab-on-chip technique for the detection of pathogens by means of their genetic material. The method is so sensitive that it was able to detect as few as 16 copies of DNA from salmonella—in less than an hour.Since the introduction of the polymerase chain reaction (PCR)—which has become the primary method for the duplication of genetic material—into clinical diagnosis, the detection of many pathogens has become significantly more reliable and sensitive. However, even PCR requires a great deal of equipment and time, involving bulky apparatus, precisely maintained temperature cycles, and successive addition of reagents. All of this demands a certain expertise from the operator.
In a tiny chamber on the chip, enzymes generate copies of the DNA contained in the sample. Six different primers, single-stranded fragments of the target DNA with a start sequence for the enzymes, act as the starting point. Methylene blue, a dye that lodges in DNA strands, serves as the electrochemical detection reagent. At first, most of the methylene blue molecules are free in the solution and come into contact with electrodes that are mounted in the chamber.When a cyclic voltage is applied, redox reactions between the electrode and the methylene blue produce a current. The more copies of the DNA that are produced, the more methylene blue is lodged in the strands, making it unavailable to the electrodes, thus causing the current to decrease. This goes faster when more pathogenic DNA strands are contained in the sample. The time at which the current signal is at its maximum can be determined so accurately that the researchers can use it to quantify the concentration of pathogen.
A future chip could support multiple chambers for the parallel detection of different pathogens. This could then be used as a prototype for the development of effective rapid tests for point-of-care diagnosis, food safety, environmental monitoring, and the fight against biological weapons.
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201109115
For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)
New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
27.06.2017 | Power and Electrical Engineering
27.06.2017 | Information Technology
27.06.2017 | Physics and Astronomy