A novel achiral fluorescent nanoprobe for the chiral recognition of cysteine enantiomers

Chiral recognition is of great significance in the field of life science and chemistry. The design and synthesis of chiral nanomaterials have become an important way to realize chiral recognition, while the application of non-chiral materials in this regard is still rare. Here, synthesis of achiral carbon dots (Asn-CDs) using racemate (DL-Asn, Asn) as nitrogen source is proposed, and chiral recognition of cysteine enantiomers (L-/D-Cys) is achieved by employing metal Co2+ as the inducible factor to co-structure a fluorescent probe (Asn-CDs+Co2+). And then, based on the ability of Co2+ to quench the fluorescence of Asn-CDs and L-cysteine (L-Cys) could restore the fluorescence of the Asn-CDs+Co2+ probe, so achieve an “on-off-on” detection mode to detect L-Cys. The Asn-CDs+Co2+ probe can distinguish cysteine enantiomers not only by fluorescence spectra but also by circular dichroism spectra. The probe can be used for the quantitative detection of L-Cys by fluorescence method. Under the optimal conditions, the linear range of L-Cys detection is 1.824–625.0 μM, and the detection limit is 0.6081 μM. The method has the advantages of high sensitivity, good selectivity, a wide linear range, and fast response. This work may provide a new idea for chiral analysis based on achiral materials.