New Method For Biochemical Analysis Of Fluids Offers Promise For Improving Water Testing

An international science team, led in part by Arizona State University (ASU) researchers, announced they have developed a new method for biochemical analysis that offers promise for advances in medicine and environmental protection.

Called "digital magnetofluidics," it promises more rapid, more accurate and less costly analyses of water and biological fluids -- blood, urine saliva -- that require only miniscule amounts of fluids.

A detailed explanation of the process is presented in an article published in the July 17 edition of Applied Physics Letters, an international journal reporting on significant new findings in physics applied to engineering, technology and other sciences. The article, "Discrete Magnetic Microfluidics," can be viewed online at http://apl.aip.org.

Digital magnetofluidics enables tiny drops of fluids to be manipulated on a silicon chip in ways that produce clearer pictures of the proteins, DNA, bacteria, viruses and chemicals present in liquids, explained Antonio Garcia, a professor in the Harrington Department of Bioengineering in ASU's Ira A. Fulton School of Engineering.

The new method holds hope for significant improvements in such areas as prognosis and diagnosis of medical conditions and in testing of water sources for environmental hazards, Garcia said.

At ASU, Garcia is among scientists and engineers developing microfluidic and test-surface techniques. The team includes Mark Hayes and Devens Gust, both professors of chemistry and biochemistry, and Tom Picraux, who spent the past four years on the ASU chemical and materials engineering faculty before recently becoming chief scientist for the Center for Integrated Nanotechnologies at the Los Alamos National Lab in New Mexico.

They were aided by ASU postdoctoral research fellow Solitaire Lindsay and graduate students Dongqing Yang, Pavan Aella and Ana Egatz-Gomez.

The ASU group's work is part of the international effort by the Interdisciplinary Network of Emerging Science and Technology (INEST), directed by Manuel Marquez, an adjunct professor of bioengineering at ASU.

Marquez, and fellow researchers in Spain, including professors Sonia Melle at Universidad Complutense de Madrid and Miguel Angel Rubio, and graduate student Pablo Dominquez-Garcia at Universidad Nacional de Educacion por Distancia, who have produced the first demonstration of the new technology, are an integral part of the microfluidics project.

The team's findings could have a vast impact on the field of bioanalysis, Hayes said.

The key to the method's effectiveness is using nanoscale surface patterns to create a "superhydrophobic" (or water-repellent) surface on which to collect extremely tiny droplets of fluids -- a surface formed by mimicking the natural self-cleaning process exhibited by the leaves of the Lotus plant, Hayes explained.

Water and biological fluids typically bead up like a ball on superhydrophobic surfaces, but the introduction of a magnetic field produced by injecting tiny magnetic particles into the droplets keeps the ball from rolling off the surface.

This allows for the fluids to be controlled through exerting magnetic force, and moved with extreme precision across the tips of nanowires, which are only about 200 atoms in diameter and less than a hundredth of the width of a human hair in length.

"We knew we had the perfect surface on which to analyze drops of blood and other biological fluids because the trapped air between the wires never allows for much of the fluid to come into contact with the surface," Garcia said.

That is crucial to accurate analysis because it prevents the chemicals and other materials in the droplet from combining and reacting with the chemical compounds in the surface material and thereby contaminating the test sample of fluid.

The process is the crux of what the researchers call "lab on a chip" technology, which will enable scientists, health care professionals and environmental experts to obtain precise biochemical test results with only micro-level amounts of fluids.

"By manipulating droplets so carefully and preventing contamination of the samples, we can detect things like signs of disease or environmentally hazardous materials much better," Lindsay said. "We can analyze things using small droplets that normally would require much larger amounts of fluid for testing. This reduces the expense of testing because you don't need large amounts of very expensive chemicals to do the analyses."

Perhaps the most critically important thing the method will help save is time, especially in medical diagnoses. "You might be able to get an analysis of someone's health condition in 15 minutes rather than having it take two days," Picraux said.

Digital magnetofluidics will allow for more compact and portable testing instruments that will work fast and require less power to operate, he said.

It also holds promise for improving public safety and homeland security efforts, Picraux said. The method could aid in more quickly and accurately detecting and analyzing dangerous chemicals if they were intentionally introduced into the environment. It also could improve monitoring systems in factories and other industrial operations where potentially hazardous chemicals are in use.

Antonio Garcia: http://www.fulton.asu.edu/~bme/faculty/core/garcia.php

This article originally appeared in the 07/01/2006 issue of Environmental Protection.

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