Chiral Sensing of Tryptophan Enantiomers Based on the Enzyme Mimics of β-Cyclodextrin-Modified Sulfur Quantum Dots

Abstract

Chiral recognition of amino acid plays a significant role in pharmaceutical, medical, and food science. This study describes a chiral sensing system of β-cyclodextrin (β-CD)-coated sulfur quantum dots (CD-SQDs) for the selective fluorescence recognition of tryptophan (Trp) enantiomers. CD-SQDs were prepared by a facile assembly fission method and could selectively recognize <i>L</i>-Trp by the different binding ability between <i>L</i>/<i>D</i>-Trp and β-CD. The inclusion of <i>L</i>-Trp and the stereoselective catalysis of CD-SQDs enzyme mimics cause the increased fluorescence intensity of CD-SQDs, which has a linear response ranging from 10 to 500 nM and the detection limit as 2.3 nM. CD-SQDs also show great selectivity for <i>L</i>-Trp from the commercial compound amino acid injection. The study could provide an effective method for the chiral recognition of amino acid enantiomers based on the catalytic activity of nanoenzymes.