Electrochemical detection of testosterone by use of three-dimensional disc-ring microelectrode sensing platforms: application to doping monitoring.

Testosterone is one of the androgenic steroid hormones, the consumption of which is considered doping in most sports. Here, we present powerful 3D sensing platforms using novel disc-ring microelectrode array devices and exploit them for the competitive immunosensing of testosterone. Each device contains a microelectrode array that consists of a large number of individual microdiscs and is used as the substrate for immunofunctionalization and assay performance. One micrometer above it, a second microelectrode array, this time consisting of microrings, is used as the working electrode for electrochemical monitoring. The physical separation of these two functions allows the incorporation of relatively thick biocomponent layers during immunofunctionalization of the microdiscs without negatively affecting electrochemical detection at the rings. Moreover, it permits electrochemical activation of the latter immediately before substrate addition and hence enables optimal electrode performance. The optimized assay showed a linear range between 0.01 and 10 ng/mL and a limit of detection of 12.5 pg/mL testosterone with detection times of 45 min.