Detection of DNA hybridization by a field‐effect transistor with covalently attached catcher molecules

Electronic DNA sensors based on field-effect transistor (FET) arrays operating in liquid environments offer an alternative method for the detection of biomolecular binding events without the requirement to label the analyte molecules. In order to obtain reproducible signals from such sensors, the attachment of the probe molecules to the gate area of the transistor chips requires a well-controlled supramolecular architecture. The FET chips used in this work are non-metallized, 8-channel transistor devices with micrometer dimensions of the gate structures, which are encapsulated to be dipped into an analyte solution. Two identical chips were functionalized with DNA catcher molecules of different sequences and read out in a differential measurement approach. In this article, we describe the details of the surface modification and covalent attachment of the catcher DNA. The surface modification was characterized by XPS, Fourier transform infrared spectroscopy (FT-IR), fluorescence microscopy and imaging ellipsometry. Electrical FET recordings of the immobilization and hybridization of DNA molecules are presented.