Sensing tyrosine enantiomers by using chiral CdSe/CdS quantum dots capped with N-acetyl-l-cysteine.

Despite of the importance of enantiomers, the fluorescence sensing of enantiomers and the interpretation of the "preferential interaction" still remain insufficiently explored. In this study, we report the recognition of tyrosine (Tyr) enantiomers by chiral N-acetyl-L-cysteine (L-NAC) capped CdSe/CdS quantum dots (QDs) under alkaline experimental condition. L-Tyr could greatly quench the fluorescence of CdSe/CdS QDs, while D-Tyr displayed no effect on the fluorescence. The one-step synthesized chiral L-NAC-CdSe/CdS QDs demonstrated high selectivity for Tyr enantiomers. In particular, the mechanism of chiral recognition has been studied by UV/vis absorption spectra and circular dichroism (CD) spectra. The changes of intensity and sign of CD spectra corroborated the attachment of L-Tyr to the surface of QDs, which may be valuable aids in obtaining a better understanding of the possible mechanism of enantioselective recognition.