| Abstract
| - Silicon nitride is the most commonly used passivation layer in biosensor applications where electronic componentsmust be interfaced with ionic solutions. Unfortunately, the predominant method for functionalizing silicon nitridesurfaces, silane chemistry, suffers from a lack of reproducibility. As an alternative, we have developed a silane-freepathway that allows for the direct functionalization of silicon nitride through the creation of primary amines formedby exposure to a radio frequency glow discharge plasma fed with humidified air. The aminated surfaces can then befurther functionalized by a variety of methods; here we demonstrate using glutaraldehyde as a bifunctional linker toattach a robust NeutrAvidin (NA) protein layer. Optimal amine formation, based on plasma exposure time, wasdetermined by labeling treated surfaces with an amine-specific fluorinated probe and characterizing the coverage usingX-ray photoelectron spectroscopy (XPS). XPS and radiolabeling studies also reveal that plasma-modified surfaces,as compared with silane-modified surfaces, result in similar NA surface coverage, but notably better reproducibility.
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