Stress is often called "the silent killer" because of its stealthy and mysterious effects on everything from heart disease to mental health.

Now researchers have developed a new test that can easily and simply measure common stress hormones using sweat, blood, urine or saliva. Eventually, they hope to turn their ideas into a simple device that patients can use at home to monitor their health. The results were published this in the journal American Chemical Society Sensors.

"I wanted something that's simple and easy to interpret," said the senior author.

The researchers developed a device that uses ultraviolet light to measure stress hormones in a drop of blood, sweat, urine or saliva. These stress biomarkers are found in all of these fluids, albeit in different quantities, the senior author said.

"It measures not just one biomarker but multiple biomarkers. And it can be applied to different bodily fluids. That's what's unique," the author said.

The stress biomarkers primarily focused on in this manuscript are cortisol, serotonin, dopamine, norepinephrine, and neuropeptide Y. UV spectroscopy of stress biomarkers performed in the 190–400 nm range has revealed primary and secondary absorption peaks at near-UV wavelengths depending on their molecular structure. UV characterization of individual and multiple biomarkers is reported in various biofluids.
A microfluidic/optoelectronic platform for biomarker detection is reported, with a prime focus toward cortisol evaluation. The current limit of detection of cortisol in sweat is ∼200 ng/mL (∼0.5 μM), which is in the normal (healthy) range. Plasma samples containing both serotonin and cortisol resulted in readily detectable absorption peaks at 203 (serotonin) and 247 (cortisol) nm, confirming feasibility of simultaneous detection of multiple biomarkers in biofluid samples.

UV spectroscopy performed on various stress biomarkers shows a similar increasing absorption trend with concentration. The detection mechanism is label free, applicable to a variety of biomarker types, and able to detect multiple biomarkers simultaneously in various biofluids.

A microfluidic flow cell has been fabricated on a polymer substrate to enable point-of-use/care UV measurement of target biomarkers. The overall sensor combines sample dispensing and fluid transport to the detection location with optical absorption measurements with a UV light emitting diode (LED) and photodiode. The biomarker concentration is indicated as a function of photocurrent generated at the target wavelength.

"You're not going to replace a full-panel laboratory blood test. That's not the intent," the seniro author said. "But if you're able to do the test at home because you're not feeling well and want to know where you stand, this will tell whether your condition has changed a little or a lot."

https://www.uc.edu/news/articles/2019/05/n20836470.html

https://pubs.acs.org/doi/10.1021/acssensors.9b00301