Fixation of DNA directly on optical waveguide surfaces for molecular probe biosensor development

Covalent attachment of DNA molecules to the surface of silicon nitride without an intermediate polymer layer is described. It is shown that the silicon nitride has a sorption capacity no less than 200 pg/mm 2, hybridization efficiency being close to 100%. The expected value of refractive index changes in the molecular layer under hybridization is estimated as sufficient for the operation of two kinds of waveguide-containing transducers.