Fluorescence turn-on recognition of chiral amino acids using dye incorporated β-CD functionalized AuNPs assembly

An assembly of dye incorporated β-cyclodextrin (βCD) functionalized AuNPs for the fluorescent probing of chiral amino acids is presented. Gold nanoparticles (AuNPs) possessing a high extinction coefficient function can be used as excellent fluorescent quenchers in AuNP-fluorophore system. Inclusion of fluorescein (FL) into β-cyclodextrin (βCD) makes energy transfer to occur through the donor and quencher nearby. This energy transfer switches off by virtue of the analyte induced release of FL from β-CD cavity, which results in the fluorescence recovery of the quenched dye. Analysis suggests that the assembly of AuNPs-βCDs-FL is effective as a turn-on fluorescent probe for the chiroselective optical discrimination between d,l-tryptophan, d,l-phenyl alanine and d,l-tyrosine. The detection limits for analyzing l-tryptophan, l-phenyl alanine and l-tyrosine were found to be 0.59, 1.2 and 1.5 μM respectively.