Glyco-macroligand microarray with controlled orientation and glycan density.

We report a new type of glycan microarray, namely, oriented and density-controlled glyco-macroligand microarray based on end-point immobilization of glycopolymer that was accompanied with boronic acid (BA) ligands in different sizes as detachable "temporary molecular spacers". Briefly, an O-cyanate chain-end functionalized lactose-containing glycopolymer was pre-complexed with polyacrylamide-BA, lysozyme-BA, and bovine serum albumin (BSA)-BA conjugates as macromolecular spacers first and then immobilized onto an amine-functionalized glass slide via isourea bond formation both at pH 10.3, respectively. Subsequently, the macromolecular spacers were detached from the immobilized glycopolymers at pH 7.4 so as to afford the oriented and density controlled glycopolymer microarrays. The spaced glycopolymer microarray showed enhanced lectin (Arachis hypogaea) binding compared to a non-spaced one. Among them, the polyacrylamide-BA spaced glycopolymer showed the highest level of lectin binding compared to lysozyme-BA- and BSA-BA-spaced glycopolymers. Furthermore, SPR results confirmed the same trend of density-dependent lectin binding as the glycoarray. This glyco-macroligand microarray platform permits variations of glycan density in the polymer, glycopolymer density and its orientation on the microarray surface and thus will provide a versatile tool for profiling glycan recognition for both basic biological research and practical applications.