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

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.