Surface-specific washing-free immunosensor for time-resolved cortisol monitoring

Cortisol is a steroid hormone that regulates wide range of vital processes. Its level changes with diurnal rhythm and reacts to stress. Measurement cortisol levels still complex multi-step process. A reversible washing-free registration method required. Here we describe metal-enhanced fluorescence assay based on displacement dye labeled BSA-cortisol conjugate from the immune immobilized golden islands by free cortisol. This competitive approach allows time-resolved monitoring fluorescent signal, surface-enhanced gold film, provides possibility continuous real-time implantable immunosensor, which was not demonstrated so far even in vitro.