Modification of silicon nitride with oligo(ethylene glycol)-terminated organophosphonate monolayers

•Organophosphonate-based functional interfaces were prepared on silicon nitride surfaces.•By water contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy a detailed characterization of the morphology, composition, and stability of the organophosphonate functional interface is presented.•Only at 700 K relevant losses of surface phosphorus can be observed suggesting the complete desorption of the organic overlayer.•SAMPs functional interfaces containing only a few numbers of ethylene glycol units exhibit remarkable protective properties against non-specific DNA physisorption. Due to its unique properties, silicon nitride has found a wide variety of applications in nanodevice fabrication and biosensing. Self-assembled monolayers of phosphonic acids (SAMPs) can be applied to prepare well-defined organic interfaces suitable to anchor bioreceptor probes with a high surface density on different substrates. In this work, we report on the fabrication of SAMPs functional interfaces on silicon nitride. By using several surface analysis techniques, including contact angle (CA) measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS), we present a detailed characterization of the morphology, composition, and stability of the functional interface. In addition, we investigate the protective properties of organophosphonate functional interfaces containing only a few ethylene glycol (EG) units per SAMPs building block against non-specific surface binding of charged biomolecules by means of fluorescence spectroscopy. [Display omitted]