Immobilization of oligonucleotide probes on Si₃N₄ surface and its application to genetic field effect transistor

Abstract

We have been developing a genetic field effect transistor (FET) which is based on potentiometric detection of allele-specific oligonucleotide hybridization on the Si₃N₄ gate insulator. In this study, the surface characteristics of DNA-immobilized Si₃N₄ film were investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and a genetic field effect transistor. The immobilization of oligonucleotide probes on the Si₃N₄ surface was analyzed by the mass spectra and the electrical potential signals. By the use of the genetic field effect transistor, the immobilization density of oligonucleotide probes on the Si₃N₄ gate insulator was calculated as 1.7×10⁸/cm² from the threshold voltage shift and was considered to influence the sensitivity of DNA hybridization detection.