| Abstract
| - This paper presents a strategy for immobilizing biomolecules on aphotoactivable surface. A self-assembled monolayer is prepared by adsorbing an ω-functionalizeddialkyl disulfide on gold. Functionalgroups of this monolayer are converted in two steps into a benzophenonederivative with an overall yieldof 50 ± 10%. Several independent techniques (ellipsometry,X-ray photoelectron spectroscopy, scanningelectron microscopy, atomic force microscopy, radiolabel assay, andautoradiography) characterize thereaction and photoimmobilization of antibodies on this surface.The photoimmobilized antibodies coverthe surface as a homogeneous and dense monolayer that could not bedisrupted by vigorous washing withthe detergent Tween 20. Immunoassays demonstrated specificrecognition of the immobilized immunoglobulins as measured by their complexation with alkalinephosphatase-linked antibodies. The methodof photoimmobilization used here leads to a homogeneous single layer ofIgGs, in which the proteinsmaximize their contact with the surface. Residual adsorption ofIgG on the nonirradiated surface ofbenzophenone remains one limitation of this approach.Progressively higher coverages of IgGs on thesurface did not lead to strictly proportional changes of the biologicalactivity of these surfaces, probablybecause of interactions between the IgGs in the film. This methodof photoimmobilization is nonethelessuseful as an experimental system to immobilize other proteins becauseit is simple, flexible, and efficient.
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