Studying the interaction of carbohydrate–protein on the dendrimer-modified solid support by microarray-based plasmon resonance light scattering assay

Abstract

Here, a three-dimensional (3D) carbohydrate microarray-based plasmon resonance light scattering (RLS) assay has been established for studying carbohydrate–lectin binding with high selectivity. The 3D carbohydrate microarray is fabricated by immobilizing amino-modified carbohydrates on the home-made fourth-generation (G4) NH₂-terminated poly(amidoamine) dendrimers (PAMAM)-modified substrate. After marking the carbohydrate–lectin binding events by 13 nm peptide-stabilized gold nanoparticles through the biotin–avidin reaction, the 3D microarray can be directly detected by the RLS scanner without the conventional silver enhancement step. The well defined recognition systems: three monosaccharides (Man-α, Glc-α and Gal-β) with two lectins (Con A and RCA 120), have been chosen here to establish the RLS assay, respectively. Quantitative determination of the surface dissociation constants (K_D,surf) for surface carbohydrates and lectins has been achieved. In addition, inhibition values (i.e. the inhibition constants (K_i) and the concentrations of inhibitors required to produce 50% inhibition (IC₅₀)) for inhibitors in solution are also demonstrated by the saccharide competing assays.