Polymer-based photocoupling agent for the efficient immobilization of nanomaterials and small molecules

A highly efficient photocoupling agent, based on perfluorophenylazide (PFPA)-conjugated polyallylamine (PAAm), was developed for the efficient immobilization of polymers, nanoparticles, graphene, and small molecules. The conjugate, PAAm-PFPA, was synthesized, and the percentage of the photoactive moiety, PFPA, can be controlled by the ratio of the two components in the synthesis. By treating epoxy-functionalized wafers with PAAm-PFPA, photoactive surfaces were generated. Compared with the PFPA surface, these polymer-based photocoupling matrix resulted in significantly enhanced immobilization efficiencies, especially for nanomaterials and small molecules. Thus, polystyrene nanoparticles (PS NPs) and alkyl-functionalized silica nanoparticles (SNPs) were successfully immobilized on the PAAm-PFPA surface, resulting in a high material density. Graphene flakes patterned on the PAAm-PFPA surface showed improved feature resolution in addition to a higher material density compared to that of flakes immobilized on the PFPA surface. Furthermore, 2-O-α-D-mannopyranosyl-D-mannopyranose (Man2) immobilized on the PAAm-PFPA surface exhibited significantly enhanced signals when treated with lectin concanavalin A (Con A).