Immobilization of Antibodies on a Photoactive Self-Assembled Monolayer on Gold

This paper presents a strategy for immobilizing biomolecules on a photoactivable surface. A self-assembled monolayer is prepared by adsorbing an omega-functionalized dialkyl disulfide on gold. Functional groups of this monolayer are converted in two steps into a benzophenone derivative with an overall yield of 50 +/-10%. Several independent techniques (ellipsometry, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, radiolabel assay, and autoradiography) characterize the reaction and photoimmobilization of antibodies on this surface. The photoimmobilized antibodies cover the surface as a homogeneous and dense monolayer that could not be disrupted by vigorous washing with the detergent Tween 20. Immunoassays demonstrated specific recognition of the immobilized immunoglobulins as measured by their complexation with alkaline phosphatase-linked antibodies. Residual adsorption of IgG on the nonirradiated surface of benzophenone remains one limitation of this approach. The method presented here is nonetheless useful as an experimental system to immobilize other proteins because it is simple, flexible, and efficient.