Immobilization of streptavidin for immunosensors on nanostructured surfaces.

A modular immunosensor device based on silicon technology with electrochemical detection is presented. The sensor surface is functionalized with the antigen estradiol using the streptavidin-biotin system. The immobilized antigen is recognized by ferrocene-labeled antibody molecules in a competitive assay format. The ferrocene redox centers can be detected electrochemically. In order to facilitate the electron transfer, a gold layer structured in nanometer dimensions is used as an electrode. The functionalized silicon chip will be integrated into a micromachined fluid transport system. The resulting immunosensor device for estradiol represents a prototype allowing easy adaptation to other biotinylated analytes since the immobilized streptavidin serves as a universal anchor.