RESUMEN
The interaction of 11-mercaptoundecanoic acid capped gold nanoparticles (MUA-GNPs) with europium ions and aminoacids has been studied by UV-Vis spectrophotometry, fluorescence, confocal fluorescence microscopy, resonance light scattering and TEM. Results demonstrated that hyper-Rayleigh scattering emission occurs upon the addition of lysine to the MUA-GNPs-Eu(III) system, thus providing an inherently sensitive method for lysine determination. The effects of geometrical factors of the gold nanoparticles (aspect ratio, particle size, cluster formation) and the surrounding medium (pH) on this behavior are discussed. The cooperative binding interactions of Eu(3+) and lysine with gold nanoparticles permitted the discrimination of lysine from other amino acids. The probable mechanism for the spectral changes and the enhanced resonance light scattering observed is outlined.
RESUMEN
The direct monitoring of reaction progress on solid supports by fluorescence spectroscopy is described. An immobilized fluorescent tracer molecule (dansyl chloride) is used to monitor the reaction on OH resins (Argopore Wang, PS Wang, and Argogel Wang), both in batch and in parallel chemistry. Fluorescence measurements were obtained directly on solid phase. The method demonstrated to be a valuable tool for the quantitative determination of resin-bound hydroxyl groups, to study reaction kinetics and for continuously monitoring the progress of the conversion of the hydroxyl resins into the chlorinated ones. The procedure proposed is highly sensitive compared to the traditional ones. The system can be extended to monitor a variety of reactions on solid supports, and in conjunction with a well-established technique such as flow analysis, basic studies on solid-phase become possible.