Germs in food, bioterrorism, drug-resistant bacteria and viruses—these are the problems of our time that make early detection of pathogens particularly important.
Whereas conventional methods are either slow or require complex instruments, Yingfu Li and a team at McMaster University in Hamilton (Ontario, Canada), additionally supported by the Sentinel Bioactive Paper Network, have now developed an especially simple, universal fluorescence test system that specifically and rapidly detects germs by means of their metabolic products. As the researchers report in the journal Angewandte Chemie, It isn’t even necessary to know which substance the test is reacting to.
Traditionally germs have been detected through microbiological methods, which are very precise but can take days or weeks. PCR- or antibody-based methods are rapid but require many steps and special equipment. “We were motivated to develop an especially simple, but very rapid and precise method,” says Li. “It must also be universal, meaning that it should be possible to develop tests for any desired germ using the same principle.”
“When a pathogen is metabolically active and multiplying in a given medium, it releases many substances into this environment. These are what we want to use,” says Li. The idea is to produce DNAzymes that react to a pathogen-specific product. A DNAzyme is a synthetic one-stranded DNA molecule with catalytic activity. Making a large pool of DNA molecules with random sequences and subjecting these to repeated selection and amplification steps allows for the development of molecules with the desired property.
At the core of the conceptual DNAzyme is a single RNA nucleotide. To its right and left are a fluorescing dye and a quencher. A quencher is a molecule that switches off the fluorescence of a dye when it is nearby. The researchers developed a DNAzyme that binds to a specific metabolic product from E. coli bacteria, which causes the DNAzyme to change its shape. In this altered form, the DNAzyme has RNA-splitting capability and cuts its own strand at the location of the RNA nucleotide. This separates the quencher from the dye, which begins to fluoresce. The fluorescence indicates that E. coli is present in the sample. This DNAzyme does not react to other bacteria.
“Through targeted selection, it should be possible to find a specific DNAzyme for any desired germ,” says Li. “It is not necessary to know what the metabolic product is, or to isolate it from the sample.” By using a common cell culture step, it is possible for the pathogens in a sample to multiply before the test, which allows for detection of a single original cell.
Yingfu Li | Angewandte Chemie
Gene therapy shows promise for treating Niemann-Pick disease type C1
27.10.2016 | NIH/National Human Genome Research Institute
'Neighbor maps' reveal the genome's 3-D shape
27.10.2016 | International School of Advanced Studies (SISSA)
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Materials Sciences
27.10.2016 | Physics and Astronomy
27.10.2016 | Life Sciences