Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

'No muss, no fuss' miniaturized analysis for complex samples developed

19.11.2009
The goal of an integrated, miniaturized laboratory analysis system, also known as a "lab-on-a-chip," is simple: sample in, answer out.

However, researchers wanting to use these microfluidic devices to analyze complex solutions containing particulates or other contaminating materials often find that the first part of the process isn't so easy.

Effective sample preparation from these solutions can be laborious, expensive and time-consuming, involving complicated laboratory methods that must be performed by skilled technicians. This can significantly diminish the benefits associated with using miniaturized analytical techniques. Recent work at the National Institute of Standards and Technology (NIST) could help change that.

NIST researchers Elizabeth Strychalski and David Ross, in collaboration with Alyssa Henry of Applied Research Associates Inc. (Alexandria, Va.), have developed a novel and simple way to analyze samples that are complex mixtures, such as whole milk, blood serum and dirt in solution. In a paper published recently in Analytical Chemistry,* the team describes its latest enhancement to a NIST-developed separation technique called gradient elution moving boundary electrophoresis (GEMBE) (see "New Miniaturized Device for Lab-on-a-Chip Separations" in NIST Tech Beat, Jan. 19, 2007).

GEMBE relies on a combination of electrophoresis and variable pressure-driven flow through a microchannel. Electrophoresis uses electricity to push a mixture in solution through a channel, forcing the individual components to separate as they move at specific rates based on their individual properties, such as size and electrical charge. Complex samples can be difficult to separate cleanly because components in these samples (for example, the fat globules in milk or proteins in blood) can "foul" microfluidic channels in a way that prevents reliable detection of the desired sample components.

The new technique solves this problem by pumping a buffer solution under controlled pressure in the opposite direction. This opposing pressure flow acts as a "fluid gate" between the sample reservoir and the microchannel. Gradually reducing the pressure of the counterflow opens the "gate" a little bit at a time. A specific sample component is detected when the pressure flow becomes weak enough—when the "gate" opens wide enough—that the component's electrophoretic motion pushes it against the pressure flow and into the channel for detection. In this way, different components enter the channel at different times based on their particular electrophoretic motion. Most importantly, the channel doesn't become fouled because the unwanted material in the sample is held out during the analysis by the pressure flow.

In their paper, the researchers validated their GEMBE analysis technique by testing it with solutions of whole milk, dirt, estuarine sediment, coal fly ash, pulverized leaves and blood serum. In all cases—and without the muss and fuss of pre-analysis sample preparation—the system was able to reproducibly separate and quantify specific components from the solutions, including potassium, calcium, sodium, magnesium, lithium and melamine.

"GEMBE is well-suited to the microfluidic analysis of 'real-world' samples," Strychalski says. "We have shown that the method can handle solutions containing particulates, proteins and other materials that would confound the majority of other microfluidic techniques."

Because of its ability to easily and rapidly characterize complex mixtures with minimal preparation, the researchers believe that GEMBE shows enormous promise for diverse applications, such as monitoring contaminants in food or water supplies, determining nutrient levels in soil, detecting biochemical warfare agents, and diagnosing medical conditions. The next steps, they say, are to miniaturize the desktop equipment now used in the system and integrate all of the parts to develop a true "lab-on-a-chip" field analyzer that can rival the effectiveness of a full-scale facility.

* E. Strychalski, A. Henry and D. Ross. Microfluidic analysis of complex samples with minimal sample preparation using Gradient Elution Moving Boundary Electrophoresis. Analytical Chemistry, Vol. 81, No. 24, Dec. 15, 2009; published online Nov. 10, 2009.

Michael E. Newman | EurekAlert!
Further information:
http://www.nist.gov

More articles from Life Sciences:

nachricht The dense vessel network regulates formation of thrombocytes in the bone marrow
25.07.2017 | Rudolf-Virchow-Zentrum für Experimentelle Biomedizin der Universität Würzburg

nachricht Fungi that evolved to eat wood offer new biomass conversion tool
25.07.2017 | University of Massachusetts at Amherst

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>