Development of fluorescent probes for “On-Off” switching based detection of lectin–saccharide interactions

Abstract

We developed a fluorescence-based monitoring system for the detection of lectin–saccharide interactions using a novel fluorescence emitter and quenching pair. The emitter; a dansyl fluorophore, was connected to concanavalin A (Con A), and quencher; a cyanopyranyl group, was bound to maltose. The fluorescence intensities of dansyl-Con A decreased specifically in the presence of cyanopyranyl-maltose. These changes were caused by a fluorescence quenching from dansyl-Con A to cyanopyranyl-maltose due to the formation of a stable complex between Con A and maltose. Fluorescence intensities could be plotted as a function of the maltose concentrations and a decrease in fluorescence was observed at concentrations of the target saccharide. Further, to demonstrate the application of this detection method, the emitter and Con A were immobilized on the surface of magnetic beads, and the monitoring of lectin–saccharide interaction was successfully performed in an easy, rapid and highly sensitive (limit of detection was 0.1nM) way. Our results clearly indicate that the novel emitter–quencher pair composed of the dansyl fluorophore and the cyanopyranyl group is a good indicator for a highly-sensitive detection of lectin–saccharide interactions.