Overview of small-molecule microarrays.
a) Upon printing, a library of small molecules with functional group A readily attach to the solid surface that is derivatized with functional group B, which is reactive to A. Coupling between an inadequate pair of functional groups (i.e., B and C) does not occur. b) When the small molecules are properly immobilized through a selective coupling (D), interactions between these molecules and their binding proteins can be detected sensitively. However, when the immobilization is inadequate (e.g., E), the immobilized small molecule is useless for the protein binding assay. Nonselective immobilization (F) enables not only the introduction of a variety of small molecules, but also the production of a variety of conjugates, some of which are expected to retain affinity toward the binding protein. c) The ideal functional group (G) should be activated under mild conditions, and the resulting species should immobilize a variety of small molecules in a functional-group-independent manner. Moreover, the functional group should not remain on the surface after the immobilization process.(Ref:3)