Molecularly imprinted electrochemical aptasensor based on functionalized graphene and nitrogen-doped carbon quantum dots for trace cortisol assay

This paper proposes a novel electrochemical aptasensor that integrates molecular imprinting techniques for trace analysis of cortisol. This sensor is based on functionalized graphene and nitrogen-doped carbon quantum dots. The morphology and structure of the modified electrode were characterized by scanning electron microscopy and Raman spectroscopy. The functional monomer aptamer and the template molecule cortisol were adsorbed on the electrode by electrostatic adsorption to construct an imprinted sensing platform. Under the optimal conditions, such as the concentration of template molecule, the ratio of template to functional monomer, the elution and adsorption time, the sensor exhibits linearity and a low detection limit of 10−12–10−8 M and 3.3 × 10−13 M, which is more sensitive than other reported cortisol analysis methods. In addition, this sensor can realize the determination of cortisol in salivary samples with high recovery values, showing great development potential in the field of life sciences.