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SUZHOU, China — Stress is an invisible enemy that affects millions worldwide, but a new scientific discovery might just make it easier to see and combat. Researchers have developed a cutting-edge sensor that can measure cortisol levels with remarkable accuracy, potentially offering a new tool in the fight against stress-related health issues.
Cortisol, often referred to as the “stress hormone,” plays a crucial role in our body’s response to stress. It regulates various bodily functions, including metabolism, immune response, and blood pressure. However, prolonged elevated cortisol levels can lead to a host of health issues, including anxiety, depression, cardiovascular problems, and weakened immune function.
Traditionally, measuring cortisol levels has been a time-consuming and expensive process, often requiring laboratory analysis of blood, saliva, or urine samples. The new sensor changes this paradigm by offering a quick, cost-effective, and highly accurate method for cortisol detection.
The heart of this new technology lies in its unique design. Scientists from Xi’an Jiaotong-Liverpool University (XJTLU) and Abertay University created a sensor using a gold electrode modified with specific molecules that can capture and bind cortisol. They then added a layer of antibodies specially designed to recognize cortisol molecules. This combination allows the sensor to detect cortisol with unprecedented sensitivity.
However, the real game-changer in this study is the use of iridium oxide as a reference electrode. Reference electrodes are crucial components in electrochemical sensors, providing a stable baseline for measurements. By using iridium oxide instead of the traditional silver/silver chloride electrodes, the researchers significantly improved the sensor’s stability and reproducibility.
“Current cortisol detectors have reference electrodes with a silver layer that is easily oxidized and unstable in electrochemical measurements,” says first author Tong Ji, a current part-time PhD student and a senior technician at XJTLU, in a statement. “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.”
A) The research team use iridium oxide to coat the reference electrode and make the cortisol detector more stable and sensitive. B) Illustration of the cortisol antibodies used on an Au electrode to create the electrochemical cortisol immunosensor. C) Cortisol detection: Larger arcs show greater concentrations of cortisol. (Credit: XJTLU/https://doi.org/10.1016/j.talanta.2024.126776)
The results of their experiments were nothing short of impressive. The sensor could detect cortisol levels as low as 11.85 picograms per milliliter – that’s less than a trillionth of a gram in a drop of liquid. This level of sensitivity far surpasses many existing methods and could allow for the detection of even the slightest changes in cortisol levels.
Moreover, the sensor demonstrated excellent performance across a wide range of cortisol concentrations, from 1 nanogram per milliliter to 1 milligram per milliliter. This broad detection range means the sensor could be useful in various scenarios, from monitoring daily stress fluctuations to diagnosing stress-related disorders.
“This is the first time iridium oxide has been used in this way,” says corresponding author Dr. Qiuchen Dong, an assistant professor at XJTLU. “Our team has 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.”
The implications of this technology are vast. Imagine a world where you could monitor your stress levels as easily as checking your heart rate on a smartwatch. This could empower individuals to take proactive steps in managing their stress, potentially preventing the onset of stress-related health issues before they become serious.
“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 huge difference to an appropriate and speedy diagnosis of high cortisol levels, drastically improving people’s lives,” says Ji.
For healthcare professionals, this tool could provide valuable insights into patients’ stress patterns, allowing for more personalized and effective treatment strategies. It could be particularly useful in managing conditions like Cushing’s syndrome or Addison’s disease, where abnormal cortisol levels play a significant role.
The researchers envision this technology being incorporated into portable, point-of-care devices, making stress monitoring accessible and convenient for everyone. While more research and development are needed before we see these sensors in everyday use, this study marks a significant step forward in our ability to understand and manage stress.
While there’s still work to be done before this cortisol sensor becomes a part of our everyday lives, its potential impact is undeniable. By giving us the ability to measure and monitor our stress levels accurately, it opens up new possibilities for personalized health care and stress management. The day when we can truly take control of our stress may be closer than we think.
Paper Summary
Methodology
The researchers created their sensor by modifying a gold electrode with a layer of 3-mercaptopropionic acid, which helps bind molecules to the surface. They then added antibodies specifically designed to capture cortisol molecules. The key innovation was using iridium oxide as the reference electrode, which provides a stable baseline for measurements. To test the sensor, they exposed it to different concentrations of cortisol and measured the electrical changes using a technique called electrochemical impedance spectroscopy. This method allows them to detect tiny changes in electrical properties when cortisol binds to the sensor.
Key Results
The sensor showed exceptional sensitivity, able to detect cortisol at concentrations as low as 11.85 picograms per milliliter. It performed well across a wide range of concentrations, from 1 nanogram per milliliter to 1 milligram per milliliter. The use of iridium oxide as a reference electrode significantly improved the sensor’s stability and reproducibility compared to traditional silver/silver chloride electrodes. The sensor also showed good selectivity, responding much more strongly to cortisol than to similar hormones like testosterone or progesterone.
Study Limitations
While the results are promising, the study was conducted in laboratory conditions using artificial samples, not real human bodily fluids. Further testing is needed to confirm its performance in real-world conditions. The researchers also noted some variability between different sensors, which could be addressed in future refinements. Long-term stability and the effects of interfering substances in complex biological samples are areas that require further investigation.
Discussion & Takeaways
The researchers emphasize that this technology could revolutionize stress monitoring, making it more accessible and convenient. They suggest it could be incorporated into portable devices for point-of-care testing. The high sensitivity and wide detection range make it suitable for various applications, from daily stress management to medical diagnostics. The use of iridium oxide as a reference electrode is highlighted as a significant advancement that could be applied to other types of electrochemical sensors.
Funding & Disclosures
The study was partially supported by the Research Development Fund from Xi’an Jiaotong-Liverpool University. The authors declared no conflicts of interest related to this research.