Breakthrough in stress detection with advanced cortisol measuring device

Stress takes different forms in our daily lives, from relentless work demands to the constant rush of school. But ignoring high stress levels can lead to serious health problems such as depression and Alzheimer’s disease.

So what if monitoring your stress levels at home became the norm? Thanks to nanoparticles, this possibility is getting closer.

In a new study published in the journal Talanta, a team from China and Britain has produced a new and improved detector that can accurately measure cortisol levels – a stress biomarker in the blood.

Tong Ji, a current part-time PhD student and senior technician at Xi’an Jiaotong-Liverpool University (XJTLU), China, is the first author of the study. She says: “A cost-effective, easily reproducible and easy-to-use point-of-care testing device that accurately measures cortisol levels has long been sought. It could make a big difference to appropriate and rapid diagnosis of high cortisol levels, dramatically improving people’s lives.”

The devices currently available generally contain electrodes that have poor stability under different and fluctuating conditions, such as changing pH and temperature. This gives the devices a short shelf life and makes them difficult to produce commercially.

“Current cortisol detectors have reference electrodes with a silver layer that oxidizes easily and is unstable in electrochemical measurements,” says Ji. “In this study, we used iridium oxide nanoparticles to cover the silver layer. This modification improves the stability, sensitivity and reproducibility of cortisol detection in point-of-care devices.”

This is the first time iridium oxide has been used in this way. Our team has produced a simple, inexpensive cortisol measuring device that detects cortisol molecules at a concentration 3000 times lower than the normal cortisol level in our blood. This makes our device sensitive enough for commercial use.”

Dr. Qiuchen Dong, assistant professor at XJTLU and corresponding author

The iridium oxide modified electrodes also improved the selectivity of testing. Dr. Graham Dawson, associate professor and co-author of Our iridium oxide-modified electrode is selective enough to distinguish the different hormones and helps solve this problem.”