New urine test could reduce need for blood samples

Marissa Pierson, a master's student, closes the lid on a centrifuge while workinh gin a Clemson lab with Professor Ken Marcus.

Marissa Pierson, a master’s student, closes the lid on a centrifuge while workinh gin a Clemson lab with Professor Ken Marcus.

If you’ve been to the doctor, you probably know what to do when you’re handed a plastic cup and shown to the bathroom.

Most patients hand over the sample and give little thought to what happens when it’s shipped to the lab for analysis. Chemistry professor Ken Marcus and his students are the exceptions. They have developed a new testing method that they believe will reduce costs, get faster results and lower the volume of urine needed for a sample.

It’s great news for patients who get the willies when the nurse pulls out the needle to draw blood. The method Marcus and his students have developed could help make it possible to use urine instead of blood to test for more diseases such as early-stage coronary heart disease or sleeping sickness.

The trouble with testing urine is that it’s awash in salt, Marcus said. It can be tricky to isolate the proteins that act as biomarkers, the clues that tell whether the patient is sick or has ingested a drug.

The magic ingredient in the group’s research looks like kite string, but it’s no ordinary twine. It’s made of capillary-channeled polymer fibers.

As part of a study, Marcus and his students packed the fibers into plastic tubes and then passed urine samples through the tubes by spinning them in a centrifuge for 30 seconds. Then the researchers ran de-ionized water through the tubes for a minute to wash off salt and other contaminants.

Proteins are hydrophobic, so they remained stuck to the fibers. Researchers extracted the proteins by running a solvent through the tubes in the centrifuge for 30 seconds. When it was all done, researchers were left with purified proteins that could be stored in a plastic vial and refrigerated until time for testing. The team was able to extract 12 samples in about five minutes, limited only by centrifuge capacity.

In urine tests commonly used now, polymer beads extract the proteins. “The difference is that ours is smaller, faster and cheaper,” Marcus said.

The team’s work was recently published by the journal Proteomics — Clinical Applications.

The research has been about a decade in the making with various students working on it over the years. Marcus said that he has graduated 33 Ph.D. students with more than half going on to work for national labs. Others work in industry and for the Centers for Disease Control and Prevention. Still others in his lab are focused on the development of analytical methods for post-detonation nuclear forensics.

For Marcus, the most important thing is to create a research environment that produces well-prepared graduates. “My pride is putting those people out and seeing them get really good jobs,” Marcus said.

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