Using nanoparticles, researchers have created a sensor that selectively detects levels of cortisol, a well-known stress biomarker, and is more robust than existing methods. Their cheap and easily reproducible device brings us a step closer to stress testing from the comfort of home.
Stress is a bugbear for many people. Whether caused by work, life circumstances, or finances, when stressed, your body releases a surge of cortisol after its ‘fight or flight’ hormones, keeping you on high alert. It’s trite to say that stress contributes to poor health.
As cortisol is a well-known stress biomarker, sensors that accurately measure its levels are important for keeping tabs on stress and intervening when necessary. To that end, researchers from Xi’an Jiaotong-Liverpool University (XJTLU) have used nanoparticles to create a cortisol-detecting device that’s cheap and accurate.
“A cost-effective, easily reproducible, and easy-to-use point-of-care testing device that accurately measures cortisol levels has long been sought,” said Tong Ji, a current PhD student and senior technician at XJTLU and the study’s lead author. “It could make a huge difference to an appropriate and speedy diagnosis of cortisol levels, drastically improving people’s lives.”
Current cortisol detectors contain silver electrodes, which tend to be unstable in extreme conditions where temperature and pH fluctuate, meaning the devices have a short lifespan and are commercially not that viable.
“Current cortisol detectors have reference electrodes with a silver layer that is easily oxidized and unstable in electrochemical measurements,” Ji said. “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.”
‘Point-of-care’ testing means the analysis is done close to or near the patient, such as at home, a pharmacy, or a medical clinic. The researchers found that electrodepositing iridium oxide (IrOx) on a gold electrode provided ultrasensitive cortisol detection.
“This is the first time iridium oxide has been used in this way,” said Dr Qiuchen Dong, an assistant professor at XJTLU and a co-corresponding author of the study. “Our team have produced a simple, low-cost cortisol measuring device that detects cortisol molecules at a concentration 3,000 times lower than the normal range of cortisol in our blood. This makes our device sensitive enough for commercial use.”
Another benefit of the IrOx-coated sensor is that it can distinguish cortisol from other similar hormones.
“One problem with the current solutions is that there is much similarity between cortisol and other hormones such as progesterone, testosterone, and corticosterone,” said Dr Graham Dawson, a professor in XJTLU’s Department of Chemistry and a study co-author. “This means it is difficult for the detectors to tell them apart. Our iridium oxide-modified electrode is selective enough to distinguish the different hormones and helps to solve this issue.”
The device brings us a step closer to performing stress testing at home.
The study was published in the journal Talanta.
Source: XJTLU
