Disposable cortisol biosensor developed

July 2, 2010 by Lin Edwards report
Image credit: Analyst, 2010, doi:10.1039/c0an00242a

(PhysOrg.com) -- Scientists in the US have developed a disposable, non-invasive new biosensor to monitor levels of the stress hormone, cortisol, and say the ultrasensitive electrochemical impedance technique it uses could transform the diagnosis of stress disorders.

Cortisol is a hormone that helps maintain blood pressure, , and carbohydrate metabolism within normal physiological limits. Abnormal levels of the hormone cortisol have been linked to stress-related disorders such as post-traumatic stress disorder, and .

The new sensor tests untreated saliva for cortisol levels, and produces results within 40 minutes. It could replace tests such as radioimmunoassays, enzyme-linked immunosorbent assays or liquid , all of which are lengthy and require the samples to be sent to a laboratory, and which often require pre-treatment of the saliva and the use of radioisotope labeling. The new biosensor gives comparable results to the laboratory assays but results can be obtained at the point of patient care. Cortisol levels in saliva correlate well with blood levels of the hormone.

The was developed by a team led by Sunil Arya of the University of South Florida in Tampa, and measures cortisol down to levels as low as 1pM. It uses a technique called electrochemical impedance spectroscopy (EIS) with a series of parallel bands of electrodes with alternate bands connected together.

The technique offers rapid reaction kinetics and improved sensitivity and increased signal-to-noise ratio, according to Arya, and the method records the information directly at the electrode surfaces without the need for radioisotope labeling.

The device is calibrated by being incubated with a range of standards for cortisol. Cortisol is a natural insulator and binds to the electrode surface, insulating and increasing the resistance. Then a solution of ferrocyanide (Fe2+) and ferricyanide (Fe3+) is used as a redox probe to measure the resistance to charge transfer from the solution to the electrode, which is proportional to the amount of in the solution.

The new method has been validated with human saliva samples, but it is not yet commercially available. Arya and the team are now exploring commercialization options, and envision it becoming available in a system rather like glucose sensors. The cost of production of the sensors would be low enough to allow them to be disposable for use at point of care.

Explore further: Symptoms of depression in obese children linked to elevated cortisol

More information: Antibody functionalized interdigitated u-electrode (IDuE) based impedimetric cortisol biosensor, Sunil K. Arya, Analyst, 2010, DOI: 10.1039/c0an00242a

Related Stories

Stress hormone, depression trigger obesity in girls

February 22, 2010

(PhysOrg.com) -- Depression raises stress hormone levels in adolescent boys and girls but may lead to obesity only in girls, according to researchers. Early treatment of depression could help reduce stress and control obesity ...

Scientists study loneliness

October 31, 2006

A U.S. scientist studying physiological dynamics of day-to-day experiences say older adults who go to bed lonely have higher cortisol levels the next day.

Fatigue in women is reduced in stress-related cortisol study

November 13, 2006

A study of healthy women has harvested results involving fatigue and vigor that eventually may help researchers fine tune efforts to treat a multitude of illnesses and syndromes linked to low levels of the stress hormone ...

Recommended for you

Destabilization processes in foam

September 19, 2017

Oktoberfest is an exciting cultural event, but it is also a source of inspiration for materials scientists and engineers. Not the beer itself, but rather the beer foam is a source of inspiration.

Solar-to-fuel system recycles CO2 to make ethanol and ethylene

September 18, 2017

Scientists at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have harnessed the power of photosynthesis to convert carbon dioxide into fuels and alcohols at efficiencies far greater than plants. ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jul 02, 2010
Chronic Fatigue Syndrome is classified by the World Health Organization in the ICD-10 under brain diseases (G93.3)along with myalgic encephalomyelitis and post viral syndrome. (A quick check of the 2006 alphabetical index on the WHO website.)

Whether stress is related to this neuroimmune disease is hotly debated since CFS has become an umbrella term with multiple conflicting research definitions and the usual conflicting bio vs. psychosocial war evidence. Cortisol has been found to be elevated or below normal levels depending on the CFS subgroup and no treatment for this conflicting results is given. Difficult to say what if any advantages would be correlated with this type of device.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.