Novel Stress Biomarker Measurement Method Uses UV Range

A recent paper described a novel label-free method for quantitative detection of human performance “stress” biomarkers in different body fluids that is based on optical absorbance of biomarkers in the ultraviolet (UV) range of the spectrum.

The concentrations of stress biomarkers (hormones and neurotransmitters) in bodily fluids (blood, sweat, urine, and saliva) predict the physical and mental state of the individual. In the current study, investigators at the University of Cincinnati (OH, USA) focused on the stress biomarkers cortisol, serotonin, dopamine, norepinephrine, and neuropeptide Y.

The investigators characterized the UV properties of individual and multiple biomarkers in various biological fluids using a microfluidic/optoelectronic platform for biomarker detection in the 190-400 nm range.

For this study the prime focus was cortisol evaluation. The current limit of detection of cortisol in sweat is approximately 200 nanograms per milliliter, which is in the normal range. UV measurement revealed that plasma samples containing both serotonin and cortisol resulted in readily detectable absorption peaks at 203 (serotonin) and 247 (cortisol) nanometers, confirming the feasibility of simultaneous detection of multiple biomarkers in biological fluid samples. UV spectroscopy performed on various stress biomarkers showed a similar increasing absorption trend with concentration.

The investigators reported that the detection mechanism was label free, applicable to a variety of biomarker types, and able to detect multiple biomarkers simultaneously in various biofluids. A microfluidic flow cell was fabricated on a polymer substrate to enable point-of-care UV measurement of target biomarkers. The overall sensor combined sample dispensing and fluid transport to the detection location with optical absorption measurements with a UV light emitting diode (LED) and photodiode.

"I wanted something that is simple and easy to interpret," said senior author Dr. Andrew Steckl, professor of electrical engineering at the University of Cincinnati. "This may not give you all the information, but it tells you whether you need a professional who can take over. These stress biomarkers are found in all of these fluids, albeit in different quantities. It measures not just one biomarker but multiple biomarkers. And it can be applied to different bodily fluids. That is what is unique."

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

The UV test for stress biomarkers was described in the May 24, 2019, issue of the journal American Chemical Society Sensors.

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