An Immunosensor for the Determination of Cortisol in Serum and Saliva by Array SPRi

Cortisol is a hormone which plays an essential role in the immune, endocrine, cardiovascular, renal and skeletal systems. Its level increases in response to stress, illness, injury or exhaustion, and it is therefore a significant diagnostic biomarker of stress. An immunosensor for the determination of cortisol by SPRi array was developed. The receptive part of the immunosensor is mouse monoclonal antibody against cortisol, immobilized via cysteamine linker. The optimum pH of the immunosensor is 7.4, and the optimum concentration of the antibody is 50 ng mL(-1). The immunosensor is specific for cortisol, and its linear response ranges from 0.20 ng mL(-1) (LOQ) to 8 ng mL(-1). The precision of the determination was between 3.1% and 3.3%, and the recovery between 99% and 102%. The immunosensor was validated by simultaneous determination of cortisol in serum and saliva samples by a standard method, with good agreement between the results.

Automated summary

Cortisol is an important hormone that plays a crucial role in multiple systems and serves as a significant biomarker for stress. A developed immunosensor for cortisol measurement demonstrates good specificity and accuracy. The results from the validation experiment show good agreement with the standard method.