Surface Functionalization Using Catalyst-Free Azide-Alkyne Cycloaddition.
The utility of catalyst-free azide-alkyne [3 + 2] cycloaddn. for the immobilization of a variety of mols. onto a solid surface and microbeads was demonstrated. In this process, the surfaces are derivatized with aza-dibenzocyclooctyne (ADIBO) for the immobilization of azide-tagged substrates via a copper-free click reaction. Alternatively, ADIBO-conjugated mols. are anchored to the azide-derivatized surface. Both immobilization techniques work well in aq. solns. and show excellent kinetics under ambient conditions. We report an efficient synthesis of aza-dibenzocyclooctyne (ADIBO), thus far the most reactive cyclooctyne in cycloaddn. to azides. We also describe convenient methods for the conjugation of ADIBO with a variety of mols. directly or via a PEG linker.