Boronic acid-functionalized nanoparticles: synthesis by microemulsion polymerization and application as a re-usable optical nanosensor for carbohydrates

Translucent boronic acid-carrying nanolatexes are prepared by copolymerisation of vinylbenzyl chloride in microemulsion followed by post functionalisation with 3-aminophenylboronic acid. The diol binding capacity and selectivity of the phenylboronic acid remain unchanged after anchoring to polymer nanoparticles (16 nm diameter, 0.22 mmol/g). The binding of a catechol dye, Alizarin Red S (ARS), to the boronic acid-carrying nanoparticles affords a colored, stable, nanolatex which is used for the selective visual detection of fructose in a competitive assay. The binding of fructose at pH 8.2 is readily evidenced by a color change and monitored by UV/Vis spectroscopy. The nanosensor can be regenerated in acidic medium. The entrapment of the nanolatex in a dialysis cell provides a re-usable support for binding and optical detection. (C) 2004 Elsevier Ltd. All rights reserved.