A Sensor System Based on a Field-Effect Transistor with a Nanowire Channel for the Quantitative Determination of Thyroid-Stimulating Hormone

Here we present an original CMOS compatible technique for fabrication a sensor system based on field-effect transistors with a nanowire channel and its application for the quantitative determination of thyroid-stimulating hormone (TSH) in model blood serum. The fabrication process is based on the reactive-ion etching of the upper layer of silicon on insulator through a mask formed by electron beam lithography. The detection is based on the registration the change in the conductivity of the transistor during the selective interaction of the analyte with specific biomolecules on its surface. There were fabricated field-effect transistors with a nanowire channel of 70-90 nm wide and 3- 5 mu m in long and a contact leads completely insulated from the analyte fluid. As the model antigen protein TSH of the pituitary gland, and as the recognition biomolecules - the specific to TSH fragments of antibodies were used, which were oriented immobilized on the nanowires surface. We carefully studied the conditions for biospecific interaction of antibodies with TSH. The detection limit of TSH was found to be 1 x 10(-4)mu IU/mL, which is significantly lower in comparison with currently used methods of standard enzyme-linked immunosorbent assay.