New analytical tool helps detect cancer

August 16, 2005

Scientists have long used ultra-fine glass tubes known as capillaries to analyze the chemical makeup of substances. Called capillary electrophoresis, or CE, the method applies high voltage to the capillaries, and by measuring the rate that the various materials move through the capillaries, researchers are able to identify individual compounds.

A group of researchers at the U.S. Department of Energy’s Ames Laboratory have developed a method called dynamic multiple equilibrium gradients, DMEG for short, that dramatically fine-tunes the process, allowing for a significant increase in resolution over previous methods. Potential applications include chemical, biological and biomedical sciences, as well as in environmental monitoring, biological warfare detection, drug discovery, and more.

“This method is hyperselective and we can design it to target specific analytes for separation,” said Ryszard Jankowiak, an Ames Lab senior scientist. “Running multiple electric field gradients can focus and move the analytes to the detection window at precisely defined times, creating signature ‘fingerprints’, which minimizes the probability of false positives.”

The advance makes it possible to detect the smallest traces of substances, such as the estrogen-derived conjugates and DNA adducts in human fluid samples that could serve as biomarkers in risk assessment of breast and prostate cancers. In fact, this and other technologies being developed at the Ames Laboratory – biosensors and fluorescence-based imaging – have been used in work with cancer researchers at the University of Nebraska Medical Center and Johns Hopkins University to identify a specific adduct in the urine of prostate and breast cancer patients, and could lead to even earlier detection or indication of cancer risk.

Unlike traditional capillary electrophoresis, Jankowiak’s team, which includes Yuri Markushin and graduate student Abdulilah Dawoud, uses only low voltage, around 2kV or less. Another difference is in the way the voltage is applied. Tiny electrodes are microfabricated along the walls of the hair-like capillaries (or channels), in essence creating a complex grid of electrodes.

“Saw-tooth type waves are applied along the channel outfitted with electrodes,” Jankowiak explains. “The electrodes act as capacitors and the applied waveforms generate electric fields. The moving variable electric field gradients induce very efficient focusing and separation of analytes. The analytes move along the capillary and tend to concentrate at the various electric field gradients. By varying the amplitude of the electric field gradients, these concentration points can be fine-tuned, making it easy to separate and identify the specific analytes.”

While the ability to design and test for specific analytes with greater accuracy marks a large leap forward in separation technology, DMEG has another, possibly even greater capability. Because the system can be fine-tuned to separate specific substances and concentrate them at particular points as they move through the capillaries, it can be used to create crystals.

“To achieve crystallization, we created multiple moving electric field gradients along the crystallization channel that can trap, concentrate, and move charged molecules (e.g. proteins) of interest,” Jankowiak said. “In other words, using the DMEG approach, we can create and electronically control many localized regions of supersaturation which can be used to produce crystals.”

One potential application for this new crystal growth method is photosynthetic complexes for use in solar/photovoltaic cells. The major stumbling block in using these materials is that they must be arranged in architectures that promote electron transport and prevent energy wasting recombination. The complexes must also be interfaced with a conducting material in order to harvest the energy. The controlled growth offered by DMEG can help overcome these hurdles.

Another possible application is for desalinization of seawater, using DMEG to extract the salt. Just recently, Jankowiak has been awarded a grant by the Office of Naval Research and NASA to pursue research in this area.

Source: Iowa State University

Explore further: Physicists turn toward heat to study electron spin

Related Stories

DNA sequencing improved by slowing down

September 21, 2015

EPFL scientists have developed a method that improves the accuracy of DNA sequencing up to a thousand times. The method, which uses nanopores to read individual nucleotides, paves the way for better - and cheaper - DNA sequencing.

The key to charging a lithium-ion battery rapidly

September 9, 2015

Lithium iron phosphate batteries are very durable and can be charged relatively quickly. Researchers from the Paul Scherrer Institute (PSI), ETH Zurich and Toyota Central R&D Labs, Inc. reveal the reasons for these properties ...

Recommended for you

Team extends the lifetime of atoms using a mirror

October 13, 2015

Researchers at Chalmers University of Technology have succeeded in an experiment where they get an artificial atom to survive ten times longer than normal by positioning the atom in front of a mirror. The findings were recently ...

A particle purely made of nuclear force

October 13, 2015

Scientists at TU Wien (Vienna) have calculated that the meson f0(1710) could be a very special particle – the long-sought-after glueball, a particle composed of pure force.


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.