Navigation Links
New magnetic separation technique might detect multiple pathogens at once

DURHAM, N.C. -- A magnetic separation technique developed by researchers at Duke University's Pratt School of Engineering and Purdue University makes it relatively simple to sort through beads hundreds of times smaller than the period at the end of this sentence.

The method could lead to new technologies for medical or environmental testing, according to the researchers. For example, specially coated magnetic particles designed to attract particular viruses or bacteria might be used in tailored combinations to simultaneously test for multiple infectious pathogens in a blood or water sample.

Benjamin Yellen, assistant professor of mechanical engineering and materials science at Duke, and Gil Lee, associate professor of chemical engineering at Purdue, report their findings in the December issue of the journal Lab on a Chip (see

"If there were five viruses that a patient might have been exposed to, you could potentially develop a technique to look for those five viruses all at the same time," Yellen said. In principle, such a test could be done with just a single drop of blood, as long as there was virus in the sample.

As an initial demonstration of the concept, the researchers attached two "model pathogens," a baker's yeast and a soil bacterium, to magnetic beads, and used their technique to selectively isolate them.

The magnetic separation method, which the researchers call magnetophoresis, uses a rotating magnetic field and a microchip containing an array of miniature magnets to separate tiny magnetic beads based on their size within a matter of minutes.

The physics behind the technique is as interesting as its potential applications, Yellen added. "The method causes certain particles to become essentially immobile -- just jittering back and forth -- while others move off the chip where they can be isolated. It implies that we could achieve effectively infinite separation between particle types. We thought our technique would work well for bioseparation, but we hadn't predicted it would be this good."

While the researchers know how to precisely control which particles move and which stay put, by varying the frequency of the magnetic field they apply, the underlying physics responsible for the behavior remains partly unexplained and will be the subject of future investigation, Yellen said.

Micrometer and nanometer sized "superparamagnetic" beads already are used widely to magnetically separate biological molecules and cells from complex fluid mixtures, Yellen said. Superparamagnetism is a form of magnetic behavior which occurs primarily in materials composed of very small magnetic grains. Such materials are commonly used for drug delivery and imaging applications and in biomedical devices because they become magnetized only in the presence of an externally applied magnetic field, which helps prevent clumping.

Over the past few decades, however, there have been few new developments in the field of magnetic separation, according to the researchers, with most of the efforts focused on using stronger and stronger magnetic fields and field gradients.

"Now, we've demonstrated a fundamentally new and different approach to magnetic separation, which can dramatically increase the separation efficiency, not by exploiting stronger fields and field gradients, but rather by precisely tuning the mobility of beads and exploiting the non-linear dynamics of particles moving in a traveling wave," Yellen said.


Contact: Kendall Morgan
Duke University

Related biology news :

1. Overbearing colored light may reveal a second mechanism by which birds interpret magnetic signals
2. Bacteria which sense the Earths magnetic field
3. Magnetic probe successfully tracks implanted cells in cancer patients
4. Magnetic system could be key to surgery without scars
5. Magnetic computer sensors may help study biomolecules
6. Rensselaer researchers develop approach that predicts protein separation behavior
7. Researchers to develop active nanoscale surfaces for biological separations
8. Einsteins tea leaves inspire new blood separation technique
9. New Technique for Tracking Gene Regulators
10. Live Recombinant Adenovirus Vaccine Technique Explored
11. New lab technique identifies high levels of pathogens in therapy pool
Post Your Comments:
(Date:11/17/2015)... , November 17, 2015 ... au 19 novembre  2015.  --> Paris ... --> DERMALOG, le leader de l,innovation biométrique, ... la fois passeports et empreintes sur la même surface ... les passeports et l,autre pour les empreintes digitales. Désormais, ...
(Date:11/16/2015)... , Nov 16, 2015  Synaptics Inc. ... human interface solutions, today announced expansion of its ... ™ touch controller and display driver integration ... of smartphones. These new TDDI products add to ... (HD resolution), TD4302 (WQHD resolution), and TD4322 (FHD ...
(Date:11/12/2015)... 2015   Growing need for low-cost, easy ... been paving the way for use of biochemical ... analytes in clinical, agricultural, environmental, food and defense ... in medical applications, however, their adoption is increasing ... continuous emphasis on improving product quality and growing ...
Breaking Biology News(10 mins):
(Date:12/1/2015)... Calif. , Dec. 1, 2015 Cepheid ... of its participation at the Piper Jaffray Healthcare Conference ... this morning, the Company is reaffirming its outlook for ... for 2016, in addition to discussing longer term business ... and Chief Executive Officer.  "We continue to be the ...
(Date:12/1/2015)... ... 01, 2015 , ... The American Society of Gynecologic Laparoscopists, ... Mathews will join fellow surgeons in the shared pursuit of “advancing minimally ... urogynecologist, founder of Plano Urogynecology Associates and Fellow of the American College ...
(Date:12/1/2015)... DUBLIN , December 1, 2015 /PRNewswire/ ... the addition of the  "2016 U.K. Virology ... Segment Forecasts for 100 Tests, Supplier Shares ... Opportunities"  report to their offering.  --> ... of the  "2016 U.K. Virology and Bacteriology ...
(Date:11/30/2015)... ... ... Global Stem Cells Group announced that its scientific team is ... adipose-derived stem cells. The announcement starts a new phase toward launching the simple, quick ... of the lipoaspirate obtained from liposuction of excess adipose tissue. , Lipoaspirate, contains ...
Breaking Biology Technology: