A core component of many types of bioassays is the interfacial chemistry of a nobel metal substrate. Self-assembled monolayers of sulfur containing compounds are typically used as the interfacial chemistry layer. While these monolayers have excellent properties for controlling interfacial chemistry, their limitations include a labile gold-sulfur interaction and a maximum coverage of only a monolayer of functional groups. In an effort to expand the surface chemistry available to modify gold, we have been investigating the electrochemical reduction of diazonium salts as a means to create layers of functionalized aryl groups. The resulting aryl films are anchored to the gold surface via a covalent bond. Another important characteristic is the ability to control the thickness of the films from mono-to multilayers by tuning the electrochemical deposition conditions. In this work a benzoic acid diazonium salt and phenyl acetic acid diazonium salt were electrochemically grafted to a gold surface using cyclic voltammetry. The ability to control surface coverage and multilayer growth was characterized using infrared reflection absorption spectroscopy (IRRAS) and atomic force microscopy (AFM). The application of these surfaces as an immunoassay support was achieved through covalent immobilization of antibodies to the activated benzoic acid surfaces. Once the antibodies were attached, antigen binding was monitored using SPR imaging. The impact of surface coverage and expansion to a multilayered surface on immunoassay performance was examined. We will demonstrate the ability of these layers to control detection limits and binding capacity for based assays. We have also extended this chemistry to the modification of gold nanoparticles. We will present our characterization of these modified nanoparticles and discuss their applications as labels for surface enhanced Raman spectroscopy.

Covalently bound aryl films for biomolecule immobilization to surfaces and nanoparticles

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.