The sensor that the researchers designed to measure stress. Credit: Sharma, V. et al.
Researchers have made a sensitive sensor that can detect extremely low concentrations of cortisol, a steroid hormone in body fluids1. Since cortisol acts as a biomarker for stress, the sensor could potentially be used to monitor stress in humans.
Monitoring stress-associated biomarker levels in body fluids can help with therapeutic interventions or stress management, the researchers say.
Existing sensors detect cortisol levels through complex and time-consuming steps. Scientists at the CSIR-Central Scientific Instruments Organisation in Chandigarh, India, have designed an easy-to-use sensor.
They synthesised graphene quantum dots by heating citric acid and treating it with sodium hydroxide solution. These quantum dots were then smeared on specific electrodes. The researchers attached short aptamers – single-stranded nucleic acids that can bind to cortisol molecules – to the top of these modified electrodes. The aptamer-containing sensor was then exposed to varying concentrations of cortisol in different solutions.
Cortisol molecules in the solutions bound to the aptamers on the sensor’s surface. The aptamer-attached cortisol molecules then detached themselves from the sensor. This structural change led to an increase in current.
Increasing the concentration of cortisol increased the peak current. The sensor selectively detected cortisol even in the presence of other natural steroid hormones and artificial steroids used as drugs.
In future, the sensor will help to detect stress by measuring the levels of cortisol in saliva and serum, the researchers note.
