Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetizing Diagnostics

16.07.2012
Magnetic Gram staining detects bacteria

Gram staining of bacteria is a routine diagnostic method of long standing that can be used for initial diagnoses and to simplify the choice of antibiotics. It is a simple way to classify bacteria into two classes—Gram-positive and Gram-negative—under a microscope. In the journal Angewandte Chemie, American researchers have now introduced an improvement to this method: magnetic Gram staining. This allows for the class-specific, automated, magnetic detection and separation of bacteria.

Gram staining was developed about a hundred years ago by Danish bacteriologist Hans Christian Gram. In this technique, bacterial cultures are colored by a stain known as crystal violet, which enters into the murein layer of the bacterial cell walls. Treatment with an iodine-containing solution forms water-insoluble complexes between the crystal violet and iodine.

There are two classes of bacteria that differ in the structures of their cell walls. A thick murein layer surrounds one class; the others have only a thin one. Whereas subsequent treatment with ethanol dissolves the stain complex out of the thin murein layer, it remains firmly lodged in the thick murein layers. Bacteria whose stain can be washed away in this manner are classified as Gram-negative; those that remain dark purple are Gram-positive.

Scientists working with Ralph Weissleder at Harvard University in Boston (USA) have now developed Gram staining into a magnetic diagnostic technique. To achieve this, they attached a “molecular hook” to the molecules of crystal violet. With this modified dye, the staining process works just as it does with the original. After staining, however, “eyes” that correspond to the “hooks” are used to attach magnetic nanoparticles to the stain. This makes it easy to quantify the bacteria: nuclear magnetic resonance (NMR) instruments detect the magnetization of the nanoparticles.

It is possible to take an NMR measurement before washing with ethanol to obtain the total number of Gram-positive and Gram-negative bacteria, and again after the washing step to determine the concentration of Gram-positive bacteria.

The advantage of this magnetic detection method is its high sensitivity. It is possible that samples could be directly magnetized and measured without prior purification or culture of the bacteria. By using the simple but sensitive miniaturized micro-NMR instruments developed by this research group, fast and sensitive on-the-spot diagnosis is conceivable. In addition, the magnetization could be used for the separation of bacteria from the sample.

About the Author
Dr. Weissleder is a Professor at Harvard Medical School, Director of the Center for Systems Biology at Massachusetts General Hospital (MGH), and Attending Clinician at MGH. His research interests include the development of novel molecular imaging techniques, tools for detection of early disease detection, development of nanomaterials for sensing and systems analysis. He is a member of the US National Academies Institute of Medicine.
Author: Ralph Weissleder, Massachusetts General Hospital, Boston (USA), https://csb.mgh.harvard.edu/weissleder/pi_bio
Title: A Magnetic Gram Stain for Bacterial Detection
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201202982

Ralph Weissleder | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Corporate coworking as a driver of innovation

22.11.2017 | Business and Finance

PPPL scientists deliver new high-resolution diagnostic to national laser facility

22.11.2017 | Physics and Astronomy

Quantum optics allows us to abandon expensive lasers in spectroscopy

22.11.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>