Chemical Surface Modification of Self-Assembled Monolayers by Radical Nitroxide Exchange Reactions

This article describes the application of nitroxide exchange reactions of surface-bound alkoxyamines as a tool for reversible chemical modification of self-assembled monolayers (SAMs). This approach is based on radical chemistry, which allows for introduction of various functional groups and can be used to reversibly introduce functionalities at surfaces. To investigate the scope of this surface chemistry, alkoxyamines with different functionalities were synthesized and were then applied to the immobilization of, for example, dyes, sugars, or biotin. Surface analysis was carried out by contact angle, X-ray photoelectron spectroscopy, and fluorescence microscopy measurements. The results show that this reaction is highly efficient, reversible, and mild and allows for immobilization of various sensitive functional groups. In addition, Langmuir-Blodgett lithography was used to generate structured SAMs. Site-selective immobilization of a fluorescent dye could be achieved by nitroxide exchange reactions.