Immunoenzymatic assay using CHEMFET devices

An IMMUNOFET device in which an antibody is immobilized onto the gate surface by means of an immunochemical membrane containing Protein A has been realized. Such a membrane is chemically linked to the device surface by using a layer of polyaminosiloxane. The antigen-antibody interaction is detected by an immunoenzymatic assay which allows the response of the immunoreaction to be amplified using as marker an enzyme (e.g., glucose oxidase) that is able to produce, during the catalysed reaction, a pH variation detected by the ISFET device. The possibility of employing this immunosensor in biomedical applications and environmental monitoring is shown using as a model system human IgG (hIgG) and the herbicide atrazine respectively.