Microbes point to method for isolating harmful forms of drugs

Apr 15, 2009
Using microfluidics and a microscope, MIT researchers were able to see the results of a sharp change in current on chiral microbes. Credit: Photo / Marcos, MIT Dept. of Civil and Environmental Engineering

(PhysOrg.com) -- Scientists at MIT and Brown University studying how marine bacteria move recently discovered that a sharp variation in water current segregates right-handed bacteria from their left-handed brethren, impelling the microbes in opposite directions.

This finding and the possibility of quickly and cheaply implementing the of two-handed objects in the laboratory could have a big impact on industries like the pharmaceutical industry, for which the separation of right-handed from left-handed molecules can be crucial to a drug's safety.

While single-celled bacteria do not have hands, their helical-shaped flagella spiral either clockwise or counter-clockwise, making opposite-turning flagella similar to human hands in that they create mirror images of one another that cannot be superimposed.

This two-handed quality is called chirality, and in a molecule, it can make the difference between healing and harming the human body.

"This discovery could impact our understanding of how water currents affect ocean , particularly with respect to their ability to forage for food, since chiral effects make them drift off-course. But it is also important for several industries that rely upon the ability to separate two-handed molecules." said Roman Stocker, the Doherty Assistant Professor of Ocean Utilization in the MIT Department of Civil and Environmental Engineering, and a principal investigator of the research.

One of the best-known instances of a chiral molecule causing widespread harm occurred in the 1950s, when the drug thalidomide was given to pregnant women to prevent . One naturally occurring form—or isomer—of thalidomide reduces nausea; the other causes birth defects. In another commonly used chiral drug, naproxen, one isomer is analgesic; the other causes liver damage.

Stocker and graduate student Marcos, along with co-authors Henry Fu and Professor Thomas Powers of Brown University, published their findings in the April 17 issue of Physical Review Letters.

In the paper, the researchers describe how they designed a microfluidic environment—a device about the size of an iPod nano that has channels containing water and bacteria—to create a "shear" flow of adjacent layers of water moving at different speeds. In their tests, Stocker and Marcos used a non-motile mutant of the bacterium Leptospira biflexa, whose entire body has the shape of a right-handed helix. They injected the Leptospira into the center of the microfluidic device and demonstrated that they drift off-course in a direction dictated by their chirality.

But the researchers did much more than observe the microbes under a microscope. In addition to the experimental data they gathered, with their Brown colleagues the MIT researchers also developed a rigorous mathematical model of the process. They are currently implementing this new approach to separate objects at molecular scales.

"The methods currently used to separate chiral molecules are far more expensive and far slower than the microfluidic option. While we still have some way to go to separate actual chiral molecules, we think our work is very promising for the agriculture, food and pharmaceutical industries." said Marcos.

Source: Massachusetts Institute of Technology (news : web)

Explore further: Refocusing research into high-temperature superconductors

add to favorites email to friend print save as pdf

Related Stories

Tiny ecosystem may shed light on climate change

Dec 15, 2008

(PhysOrg.com) -- MIT researchers have created a microbial ecosystem smaller than a stick of gum that sheds new light on the plankton-eat-plankton world at the bottom of the aquatic food chain.

Everything starts with recognition

Apr 23, 2007

A human body has more than 10 to the power of 27 molecules with about one hundred thousand different shapes and functions. Interactions between molecules determine our structure and keep us alive. Researchers ...

Controlling the building blocks of life

Dec 10, 2008

(PhysOrg.com) -- A simple and reliable method for converting one of the simplest chemical entities into one of the most difficult-to-make molecular building blocks of life, with complete control over its shape, ...

Recommended for you

Study finds physical link to strange electronic behavior

2 hours ago

Scientists have new clues this week about one of the baffling electronic properties of the iron-based high-temperature superconductor barium iron nickel arsenide. A Rice University-led team of U.S., German ...

Refocusing research into high-temperature superconductors

14 hours ago

Below a specific transition temperature superconductors transmit electrical current nearly loss-free. For the best of the so-called high-temperature superconductors, this temperature lies around -180 °C – a temperature ...

MRI for a quantum simulation

20 hours ago

Magnetic resonance imaging (MRI), which is the medical application of nuclear magnetic resonance spectroscopy, is a powerful diagnostic tool. MRI works by resonantly exciting hydrogen atoms and measuring ...

50-foot-wide Muon g-2 electromagnet installed at Fermilab

20 hours ago

One year ago, the 50-foot-wide Muon g-2 electromagnet arrived at the U.S. Department of Energy's Fermi National Accelerator Laboratory in Illinois after traveling 3,200 miles over land and sea from Long Island, ...

User comments : 0