Complexation of Dextran and glucose with thiolate boronic acid capped on nanoparticle

摘要

Tiopronin-monolayer protected silver nanoparticles (average diameter = 5 nm) were partially replaced by thiolate boronic acid via ligand exchange. The uncapped boronic acids could be coupled with both a polysaccharide (Dextran) and a monoaccharide (glucose). Boronic acids capped on the particle were coupled selectively only by Dextran. With the decrease of charge on particle surface at pH = 5, boronic acids capped on the particle could be coupled with glucose. The particles were observed to aggregate along the Dextran chain, resulting in an absorbance decrease of the transverse plasmon at 397 nm and simultaneous rising of longitudinal plasmon at 640 nm. The aggregation increased with the concentration of Dextran. Luminescence intensity of phenyl boronic acid was enhanced by an upward deviation from a line with the concentration of Dextran in solution but the decay time was decreased, principally by the aggregation of the metallic cores.