Molecularly imprinted Au nanoparticles composites on Au surfaces for the surface plasmon resonance detection of pentaerythritol tetranitrate, nitroglycerin, and ethylene glycol dinitrate.

Molecularly imprinted Au nanoparticles (NPs) composites are generated on Au-coated glass surfaces. The imprinting process involves the electropolymerization of thioaniline-functionalized Au NPs (3.5 nm) on a thioaniline monolayer-modified Au surface in the presence of a carboxylic acid, acting as a template analogue for the respective explosive. The exclusion of the imprinting template from the Au NPs matrix yields the respective imprinted composites. The binding of the analyte explosives to the Au NPs matrixes is probed by surface plasmon resonance spectroscopy, SPR, where the electronic coupling between the localized plasmon of the Au NPs and the surface plasmon wave leads to the amplification of the SPR responses originating from the dielectric changes of the matrixes upon binding of the different explosive materials. The resulting imprinted matrixes reveal high affinities and selectivity toward the imprinted explosives. Using citric acid as an imprinting template, Au NPs matrixes for the specific analysis of pentaerythritol tetranitrate (PETN) or of nitroglycerin (NG) were prepared, leading to detection limits of 200 fM and 20 pM, respectively. Similarly, using maleic acid or fumaric acid as imprinting templates, high-affinity sensing composites for ethylene glycol dinitrate (EGDN) were synthesized, leading to a detection limit of 400 fM for both matrixes.

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.