Development of a Prototype Lateral Flow Immunoassay of Cortisol in Saliva for Daily Monitoring of Stress.

Elizaveta Panfilova

doi:10.3390/bios11050146

Abstract

Emotional stress negatively affects the quality of a person’s daily life. From a physiological point of view, stress is expressed in the excitation of the hypothalamic–pituitary–adrenal cortex axis, which leads to the release of the hormone cortisol into the blood. We developed a lateral flow immunoassay to detect cortisol in human salivary fluid and tested it on 10 healthy volunteers daily for about one month (n = 293 saliva samples). Cortisol was detected in concentrations ranging from 1 to 70 ng/mL. Salivary cortisol levels were confirmed by ELISA. The straightness range of LFIA calibration was from 1 to 100 ng/mL. The diagnostic sensitivity of the method was 73%. It was found that in 3 out of 10 subjects, fluctuations in the level of cortisol in saliva partially corresponded to the subjectively assessed level of stress.

Highlights

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After a certain period of time, the resulting mixture of the conjugate and the sample is applied to the sample pad of the test strip, by means of capillary forces, the mixture moves up the test strip, simultaneously interacting or not interacting with the molecules applied to the membrane of the test strip
If the sample contains a large amount of antigen, this antigen interacts with all antibody molecules in the conjugate, as the liquid passes through the test strip, the conjugate does not interact with the antigen–protein