Coming Soon: Tuberculosis Detection with a Chip?

July 29, 2009

(PhysOrg.com) -- Many of the new techniques based on nanotechnology that have been developed for faster and more sensitive detection of pathogens fail in day-to-day clinical use because they require complex sample preparation or measurement equipment, or simply cannot keep up with the large sample throughput in a clinic. Researchers working with Ralph Weissleder at Harvard Medical School have now developed a very simple process for the rapid detection of pathogens that requires no further sample preparation.

As reported in the journal Angewandte Chemie, this technique is based on magnetic nanoparticles and a (NMR) measurement.

For their tests, the researchers used the bacillus Calmette-Guérin (BCG), a mycobacterium named after its developers, which was cultured from bovine tuberculosis bacilli in the early twentieth century. This is a weakened strain that is used as a live vaccine against tuberculosis. In addition, it serves as a model for the true tuberculosis pathogen Mycobacterium tuberculosis for research purposes.

The test is this simple: A sample is incubated in a solution that contains special magnetic nanoparticles. These nanoparticles consist of an iron core surrounded by a shell of ferrite, which is an iron oxide. The researchers attached anti-BCG antibodies to the surfaces of the nanoparticles. If BCG are present in the sample, the antibodies bind to them, thus equipping them with magnetic particles. The liquid is then introduced through microchannels into the tiny chamber of a microfluidic chip. At the exit of the chamber is a membrane that retains the bacteria while the rest of the solution, including excess magnetic particles, passes through. The bacteria thus become concentrated in the chamber.

The chamber is surrounded by a small coil, which produces the magnetic field required for nuclear magnetic resonance measurements (similar to a clinical MRI scanner). The bacteria, with their attached , influence the behavior of the nuclear spins of the water molecules in the chamber. This can be detected directly on the chip by means of the handheld miniaturized NMR system. It was thus possible to detect 20 bacilli in a sputum sample within 30 minutes.

More information: Ralph Weissleder, Ultrasensitive Detection of Bacteria Using Core-Shell and an NMR-Filter System, International Edition 2009, 48, No. 31, 5657-5660, doi: 10.1002/anie.200901791

Provided by Wiley (news : web)

Explore further: New Nanoparticle Structure Boosts Magnetic Properties

Related Stories

New Nanoparticle Structure Boosts Magnetic Properties

December 19, 2005

Magnetic nanoparticles have shown promise as contrast-enhancing agents for improving cancer detection using magnetic resonance imaging (MRI), as miniaturized heaters capable of killing malignant cells, and as targeted drug ...

Better insight into brain anatomical structures

June 15, 2007

Magnetic resonance imaging is a very effective method for revealing anatomical details of soft tissues. Contrast agents can help to make these images even clearer and allow physiological processes to be followed in real time. ...

Magnetic nanoparticles detect and remove harmful bacteria

November 19, 2007

Researchers in Ohio report the development of magnetic nanoparticles that show promise for quickly detecting and eliminating E. coli, anthrax, and other harmful bacteria. In laboratory studies, the nanoparticles helped detect ...

'NMR on a chip' features magnetic mini-sensor

February 19, 2008

A super-sensitive mini-sensor developed at the National Institute of Standards and Technology can detect nuclear magnetic resonance (NMR) in tiny samples of fluids flowing through a novel microchip. The prototype chip device, ...

Progress Toward a Biological Fuel Cell?

December 30, 2008

(PhysOrg.com) -- Biological fuel cells use enzymes or whole microorganisms as biocatalysts for the direct conversion of chemical energy to electrical energy. One type of microbial fuel cell uses anodes (positive electrodes) ...

Recommended for you

Chemists solve major piece of cellular mystery

August 27, 2015

Not just anything is allowed to enter the nucleus, the heart of eukaryotic cells where, among other things, genetic information is stored. A double membrane, called the nuclear envelope, serves as a wall, protecting the contents ...

Study reveals how nanochannels select potassium ions

August 25, 2015

(Phys.org)—One of the mysteries in biology is how cells can selectively diffuse potassium across a membrane. Biological systems rely on a delicate balance between these potassium and sodium ion concentrations in the surrounding ...

Unusual use of blue pigment found in ancient mummy portraits

August 26, 2015

Mostly untouched for 100 years, 15 Roman-era Egyptian mummy portraits and panel paintings were literally dusted off by scientists and art conservators from Northwestern University and the Phoebe A. Hearst Museum of Anthropology ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.