- Researchers develop a new technique to quickly measure common stress hormones using saliva, urine, blood, and sweat.
- Although the method is simple and inexpensive, it is not going to replace the comprehensive blood test done in a laboratory.
Allostatic stress is quite dangerous to health. It can permanently change the human immune system. Exposure to chronic or acute stress can lead to vast and detrimental physiological consequences.
Prolonged periods of stress may have some harmful effects, such as hyperglycemia, depression, weight gain or loss, cardiothoracic disease, neurological breakdown. The key biomarkers that play a major role in stress include brain-derived neurotrophic factor, neuropeptide, epinephrine, serotonin, norepinephrine, and cortisol.
Recently, a research team at the University of Cincinnati developed a technique to test and measure these biomarkers in different body fluids such as saliva, urine, blood, and sweat. This technique can be incorporated into a simple device that can be used at home to monitor health.
The lab-based biomarker evaluation is well developed and outputs precise measurements of their concentration. However, the instrumentation involved in this process is complex, costly, and time-consuming. The system operation requires lab space and expertise.
The new method, on the other hand, detects stress biomarkers using faster, simpler, and inexpensive instrumentation. It can be directly used by patients, but outputs are less accurate than that of lab testing methods.
How Did They Do This?
This new method uses ultraviolet (UV) light to measure stress hormones in a drop of saliva, urine, blood or sweat. All these fluids carry different quantities of stress biomarkers.
UV spectroscopy — used for protein quantitation — is a fast and convenient process. It doesn’t require external labels to be added on fluid, and can be directly performed on the sample. The process outputs a linear relationship between absorbance and concentration.
Human biofluids contain multiple strands of proteins, amino acids, and lipids and other molecules. The UV absorbance can be determined by the molecular structure of proteins.
Credit: Dave Wheeler / HBR
In this study, UV absorption spectroscopy carried out on the stress biomarkers had primary and secondary absorption peaks ranging from 190 nanometers to 400 nanometers. The wavelengths of these characteristic absorption peaks identified the biomarkers present in the sample. For ‘no-stress’ samples, the characteristic peaks were absent.
For point of use implementation, researchers fabricated an optical microfluidic sensor on a UV transparent hydrophilic substrate. They then integrated it with a photodiode detector and small UV LED to provide an electronic readout of the signal.
Of course, this method is not going to replace the comprehensive blood test done in a laboratory. But it can quickly tell people whether their condition has changed a lot or a little. Moreover, with further improvements in the optoelectronics components, the device will provide more accurate results.