A novel highly sensitive electrochemical immunosensor for the sensitive detection of testosterone based on...

Testosterone (T) is a steroid that accelerates muscle growth and enhances the development of male characteristics. The level of the hormone can also serve as an important indicator for diagnosing and monitoring diseases related to endocrine disorders. An electrochemical immunosensor is a detection method that combines the specific immune reaction between an antigen and an antibody and the high sensitivity of electrochemical analysis, and it has been widely used in food detection in recent years. This study describes, for the first time, an electrochemical immunosensor based on silver nanoparticles-graphene oxide (AgNPs-GO) nanocomposites-for the direct detection of the residual marker T. After the deposition of the nanocomposites onto the surface of a gold electrode, a significant enhancement in the catalytic current for the redox reaction was observed. The nanocomposites were characterised using UV-vis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The proposed immunosensor provided a limit of detection (LOD) of 0.018 ng mL^-1 over a linear range of 0.05-100 ng mL^-1. The recoveries ranged from 97.20% to 106.49% with the relative standard deviations (RSD) not more than 3.98%, indicating that the immunosensor is capable of accurately detecting T in real samples. The sensor takes advantage of the unique properties of the nanocomposites providing good stability and reproducibility, and, together with the presence of the monoclonal antibody, improves the sensitivity and selectivity of the detection and it can be used as a potential tool for the detection of T in animal-derived foods.