Detection of human salivary stress biomarkers using an easy-to-use array sensor based on fluorescent organic molecules

During stressful conditions, the human body synthesizes catecholamine neurotransmitters such as dopamine and adrenaline, and cortisol. The monitoring of these three molecules levels is crucial for stress management and holds significant medical applications. Here we developed an analytical device that incorporates a biomimetic (tongue-mimic) associated with an optical physico-chemical transducer, able to detect simultaneously cortisol, dopamine and adrenaline in human saliva without pre-treatments, using an array sensor based on fluorescent chemical receptors (BODIPY, Rhodamine, and Naphthylamides) able to interact by non-covalent interaction with cortisol, adrenaline and dopamine, leading to a change of the emission. Calibration, recovery and selectivity have been performed to validate the device. In particular, the linear responses of the array to concentration range of 1 pM-1 mM of the three analytes were demonstrated by PLS analysis, as well as the high selectivity by PLS-DA analysis performed with artificial saliva samples. Analyses in real human saliva samples, compared to the validated analytical methods, demonstrated that our prototype represents the first point-of-care device able to quantify these three analytes in human saliva with one single analysis in a wider concentration range respect to the other standard methods.