A sensor provides continuous detection of cortisol concentrations in real time. (Credit: Talanta, April 2021)

A prototype of a fluorescence-based sensor provides continuous detection of cortisol concentrations in real time, which can help monitor various health conditions. Researchers created a prototype immunosensor for cortisol monitoring using gold nanoparticles. The free cortisol in the sample displaces fluorescently marked complexes of cortisol and bovine serum albumin (BSA), which are attached to monoclonal antibodies to cortisol and put onto nanoscale gold “islands” on the sensor. The fluorescence can be measured as a signal of cortisol concentration in the sample.

In in vitro tests, the new sensor showed the lowest levels of detection for cortisol of 0.02 μg/ml, comparable to normal levels in the human plasma. The reversible response was also demonstrated in vitro. The team hopes their approach can lead to the development of an implantable sensor for continuous monitoring of cortisol concentration in real time.

Such an implantable sensor will look like an optical fiber with a capillary cell at the end covered by the semipermeable membrane placed in a thin needle. This needle will have several inside layers and will be connected to a portable spectrometer via fiber optics.

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Medical Design Briefs Magazine

This article first appeared in the July, 2021 issue of Medical Design Briefs Magazine.

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