Site-Specific Surface Functionalization via Microchannel Cantilever Spotting (µCS): Comparison between Azide-Alkyne and Thiol-Alkyne Click Chemistry Reactions.

Different types of click chemistry reactions are proposed and used for the functionalization of surfaces and materials, and covalent attachment of organic molecules. In the present work, two different catalyst-free click approaches, namely azide-alkyne and thiol-alkyne click chemistry are studied and compared for the immobilization of microarrays of azide or thiol inks on functionalized glass surfaces. For this purpose, the surface of glass is first functionalized with dibenzocyclooctyne-acid (DBCO-acid), a cyclooctyne with a carboxyl group. Then, the DBCO-terminated surfaces are functionalized via microchannel cantilever spotting with different fluorescent and nonfluorescent azide and thiol inks. Although both routes work reliably for surface functionalization, the protein binding experiments reveal that using a thiol-alkyne route will obtain the highest surface density of molecular immobilization in such spotting approaches. The obtained achievements and results from this work can be used for design and manufacturing of microscale patterns suitable for biomedical and biological applications.