New highly sensitive saliva-based cortisol sensor developed – eliminating the need for invasive blood tests

• Pioneering saliva-based point-of-care electrochemical biosensor developed for real-time cortisol tracking – avoiding the need for invasive blood tests.
• Underpinned by a Gii-Sens electrode, comparative studies reveal the biosensor has 100 times greater sensitivity compared to traditional saliva tests, ensuring reliable cortisol level measurements.
• Applications include identifying early onset of stress related metabolic and neurological disorders, measuring the wellbeing of frontline workers, and optimizing athlete performance.

A new electrochemical biosensor that is 100 times more sensitive than traditional tests for detecting cortisol levels (the “stress hormone”) in human saliva has been created.

Profiling cortisol in saliva could improve understanding of conditions that affect and are affected by long-term stress levels. Cortisol, a hormone associated with stress, fluctuates throughout the day and varies significantly among individuals. It is often tested through either saliva or blood tests.

Traditional technologies have struggled to provide reliable and sensitive detection from saliva due to it having low concentrations of cortisol. Blood tests, while more accurate, are invasive, especially if they have to be taken multiple times a day.

Published in Microchimica Acta, the Point-of-Care (POC) electrochemical biosensor developed by researchers at Tufts University School of Engineering boasts a detection limit of 0.24 fg/mL, making it vastly more sensitive than existing saliva tests. This non-invasive diagnostic tool provides reliable salivary cortisol profiles, offering crucial insights into human stress levels.

The new sensor was underpinned by a Gii-Sens electrode, created by iGii (formerly Integrated Graphene). This unique, porous, 3D carbon nanostructure has a high surface area and highly conductive carbon-based electrode platform. It is more sensitive, and more sustainable, compared to other commonly used sensor materials, such as gold. The fabrication process of this ultra-sensitive biosensor involves attaching anti-cortisol monoclonal antibodies (mAb-cort) to the PBASE-NHS/GF electrode through non-covalent immobilization. This method preserves bioreceptor Graphene’s structural integrity and electrical conductivity while facilitating efficient and controlled antibody immobilization, thereby enhancing the biosensors’ sensitivity.

Cortisol tests are important for a number of use cases. Cortisol tracking can also help identify early onset of psychological and physiological health conditions, such as stress-related metabolic and neurological disorders. They can also be used to measure the wellbeing of frontline workers. Tests are also often conducted for athletes, as high cortisol levels can be detrimental to performance.

Jean-Christophe Granier, Chief Executive Officer, iGii, said: “These results are another clear example of Gii-Sens being integrated into different biosensors to test different conditions. As well as being considerably more accurate and reliable than existing tests, Gii-Sens is much more cost-effective and sustainable than other materials, such as gold, used in medical diagnostic tests”.

Gii-Sens electrodes are proven to outperform screen-printed options on multiple levels and create a better, faster experience. The technology can be used to measure a wide range of health and environmental markers in saliva and other fluids. iGii is working closely with medical technology companies worldwide to enhance their existing diagnostic tests or help design new ones that cover all aspects of Assay Development, from initial design concept to full integration and FDA approval.