Figure 2. Preparation of lectin-functionalized fluorescently labelled polystyrene beads and their ability to bind multivalent glucosyl polymers.

(A) Concanavalin A (Con A) was immobilized onto FITC-polystyrene beads (d = 1μm) possessing surface carboxylic acid groups (FITC-PS-CO₂H) by EDC/NHS coupling. (B) ATR-FTIR spectra of (from top): FITC-PS-CO₂H beads before reaction with Con A; powdered Con A lectin; FITC-PS-CO₂H beads after reaction with Con A. (C,D) Fluorescence micrographs of suspensions of Con A – functionalized FITC-PS-CO₂H beads in HEPES buffer (C) before and (D) after addition of a water-soluble multivalent glucosyl polymer. (E) Con A functionalized FITC-PS-CO₂H beads in HEPES buffer after addition of a water-soluble multivalent fucosyl polymer (fucose does not bind to Con A). (F) unreacted FITC-PS-CO₂H beads in HEPES buffer after addition of a water-soluble multivalent glucosyl polymer.