New Analytical Tool Helps Detect Cancer

A group of researchers at the U.S.Department of Energy’s Ames Laboratory have developed a method calleddynamic multiple equilibrium gradients, DMEG for short, thatdramatically fine-tunes the process, allowing for a significantincrease in resolution over previous methods. Potential applicationsinclude chemical, biological and biomedical sciences, as well as inenvironmental monitoring, biological warfare detection, drug discovery,and more.

“This method is hyperselective and we can design it totarget specific analytes for separation,” said Ryszard Jankowiak, anAmes Lab senior scientist. “Running multiple electric field gradientscan focus and move the analytes to the detection window at preciselydefined times, creating signature ‘fingerprints’, which minimizes theprobability of false positives.”

The advance makes it possible todetect the smallest traces of substances, such as the estrogen-derivedconjugates and DNA adducts in human fluid samples that could serve asbiomarkers 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 withcancer researchers at the University of Nebraska Medical Center andJohns Hopkins University to identify a specific adduct in the urine ofprostate and breast cancer patients, and could lead to even earlierdetection or indication of cancer risk.

Unlike traditionalcapillary electrophoresis, Jankowiak’s team, which includes YuriMarkushin and graduate student Abdulilah Dawoud, uses only low voltage,around 2kV or less. Another difference is in the way the voltage isapplied. Tiny electrodes are microfabricated along the walls of thehair-like capillaries (or channels), in essence creating a complex gridof electrodes.

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

While the abilityto design and test for specific analytes with greater accuracy marks alarge leap forward in separation technology, DMEG has another, possiblyeven greater capability. Because the system can be fine-tuned toseparate specific substances and concentrate them at particular pointsas they move through the capillaries, it can be used to create crystals.

“Toachieve crystallization, we created multiple moving electric fieldgradients along the crystallization channel that can trap, concentrate,and move charged molecules (e.g. proteins) of interest,” Jankowiaksaid. “In other words, using the DMEG approach, we can create andelectronically control many localized regions of supersaturation whichcan be used to produce crystals.”

One potential application forthis new crystal growth method is photosynthetic complexes for use insolar/photovoltaic cells. The major stumbling block in using thesematerials is that they must be arranged in architectures that promoteelectron transport and prevent energy wasting recombination. Thecomplexes must also be interfaced with a conducting material in orderto harvest the energy. The controlled growth offered by DMEG can helpovercome these hurdles.

Another possible application is fordesalinization of seawater, using DMEG to extract the salt. Justrecently, Jankowiak has been awarded a grant by the Office of NavalResearch and NASA to pursue research in this area.

AmesLaboratory is operated for the Department of Energy by Iowa StateUniversity. The Lab conducts research into various areas of nationalconcern, including energy resources, high-speed computer design,environmental cleanup and restoration, and the synthesis and study ofnew materials.