Studying sweat, the small stuff

Imagine if you could know the status of any molecule in your body without needing to get your blood drawn. Science fiction? Almost – but researchers at the University of Arizona are working on ways to do this by measuring molecules in sweat.

When physicians take blood samples from patients, they send the samples to labs to be analyzed for biomarkers. These biological clues indicate everything from cholesterol levels to disease risks, and they can be used to monitor patient health or make diagnostic decisions. The same biomarkers also are found in sweat.

Using $519,000 in funding from the SEMI Nano-Bio Materials Consortium, or SEMI-NBMC, Erin Ratcliff, University of Arizona materials science and engineering professor and head of the UArizona Laboratory for Interface Science of Printable Electronic Materials, is leading a project to develop new ways of collecting and analyzing the clues sweat has to offer. Ultimately, this work could allow physicians to use patient sweat samples in the same way they currently use blood samples, for a less invasive and more informative approach to establishing and monitoring patient health.

“What’s unique about this is that we are combining biology and engineering expertise to develop a wearable device that will detect molecules in sweat, so you don’t have to get your blood drawn to know the health status of your immune system, your nervous system, indeed, any system in the body,” said co-investigator and sweat biomarker pioneer, Dr. Esther Sternberg. “The goal, eventually, is to create a device that will provide physicians and health care providers the ability to monitor your health status continuously and in real-time without needing to draw blood.”

“We are pleased to sponsor and eager to complete this project with University of Arizona’s impressive team bridging the disciplines of engineering and life sciences,” said Melissa Grupen-Shemansky, chief technology officer and executive director of SEMI-NBMC. “A concerted interdisciplinary approach at the early stages of R&D is relatively new, and there is much learning on both sides. The UArizona team brings unique strengths in both areas, and we are excited to be partnering and collaborating with them.”

Ratcliff’s co-investigators are J. Ray Runyon, a research assistant professor in the Department of Environmental Science, and Sternberg, research director for the Andrew Weil Center for Integrative Medicine; director of the Institute on Place, Wellbeing, and Performance; and the Andrew Weil Inaugural Chair for Research in Integrative Medicine. All three researchers are members of the BIO5 Institute.

Standardized Sample Collection

In order to study sweat, researchers need to collect samples of it, and there are a number of ways to do so.

“The obvious idea would be to make a patch that gets information from many pores at once, but the problem is that this creates a space between the patch and your skin, and you have to wait for it to fill up with sweat,” Ratcliff said. “We hypothesize that while you’re waiting, these molecules – the very molecules you’re trying to detect and analyze – are changing chemically.”

The team’s first task is to develop new, continuous and hands-free collection devices that deliver high-quality, standardized sweat samples. This will allow health care professionals to gain a more holistic picture of a patient’s bodily systems over an extended period, rather than the “snapshot” a blood draw can provide of a particular moment.

Currently, sweat labs across the world are using different methods to collect samples, which limits researchers’ ability to compare data. Standardizing the collection method could provide researchers, including medical device developers, with a new degree of confidence in sweat sample data.

“High-quality data, with respect to different target molecular biomarkers in sweat, requires that a high-quality sample be collected,” Runyon said. “This will be the first hands-free method that will truly take into account the interplay of the chemistry of sweat, the target biomarker and the device material.”

Low-Level Detection

The team is also developing methods for researchers to detect and analyze neuropeptides in the collected samples. Used by neurons to communicate with each other, these small molecules are involved in biological functions, including metabolism, reproduction and memory. Commercial wearable devices monitor metrics like heart rate, and some use sweat sensors to monitor dehydration level. Measuring neuropeptides, however, will allow researchers to zoom in millions of times closer to investigate stress and relaxation responses at the molecular level.

“The idea is that your sweat is reflecting your nervous system – all of the neurotransmitters your body uses to signal between the brain and the rest of the body,” Ratcliff said. “Monitoring this biochemical response continually, over a 24-hour cycle, can inform us about the health of the wearer and also act as a diagnostic tool.”

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