A novel supramolecule-based fluorescence turn-on and ratiometric sensor for highly selective detection of glutathione over cystein and homocystein.

Abstract

Acyclodextrin-based fluorescence light-up and ratiometric sensor is reportedfor highly selective and sensitive recognition of glutathione over cystein and homocystein. The sensing scheme developed builds up on a supramolecular assembly formed between a molecular rotor dye (ThT) and a polyanionic supramolecular host (sulfated-β-cyclodextrin, SCD). The detection scheme is accomplished as follows: firstly, the bivalent Cu2+ quenches the emission from ThT-SCD assembly by causing the dissociation of ThT molecules from SCD surface. Secondly, when GSH is added to the copper-quenched system, owing to specific interaction between Cu2+ and GSH, Cu2+ is removed from the SCD which again allows the formation of ThT-SCD assembly. Indeed, this scheme of disassembly and reassembly successivelycaused by Cu2+ and GSH in the aqueous solution empowers our sensor framework to work as a good ratiometric sensor for the detection of GSH. The sensor scheme shows a linear response in the range 0-250μM with a LOD of 2.4 ± 0.2μM in aqueous solution and 13.6 ± 0.5μM in diluted human serum sample. The sensor system is excited at 410nm and the emission signal is plotted as a ratio of intensity at 545nm (aggregate band) and 490nm (monomer band). This ratiometric sensor system is highly selective to glutathione over cystein, homocystein, and other amino acids. Additionally, response of the sensor system towards GSH in complex biological media of serum samples demonstrates its potential for practical utility. Graphical abstract.