Selective and enantioselective analysis of mono- and disaccharides using surface plasmon resonance spectroscopy and imprinted boronic acid-functionalized Au nanoparticle composites.

A method was developed for the synthesis of molecularly imprinted Au nanoparticle (NP) composites on electrodes by electrochemical means. The resulting composites include specific recognition sites for mono- or disaccharides. The method is based on the formation of a boronate complex between the respective saccharide and the boronic acid ligands associated with the Au NPs. The electropolymerization of the Au NPs leads, after cleavage of the respective boronate esters, and removal of the saccharide, to specific recognition sites for the association of the imprinted monosaccharides or disaccharides. The binding of the saccharides to the imprinted sites is followed by surface plasmon spectroscopy (SPR). The changes in the refractive index of the Au NP composites upon the binding of the saccharides to the imprinted sites are amplified by the coupling between the localized plasmon associated with the NPs and the surface plasmon wave propagating on the Au surface. This leads to the highly sensitive stereoselective and chiroselective detection of monosaccharides and disaccharides.