A new nanosensor for the chiral recognition of cysteine enantiomers based on gold nanorods

Abstract

An easy-to-use, fast and highly selective method, which used unmodified gold nanorods (GNRs) as a chiral nanosensor for the chiral recognition of cysteine (Cys) enantiomers, has been developed in this work. Under the optimized conditions, L-Cys caused GNRs aggregation, and the absorbance decrease of GNRs at a wavelength of 650 nm was 0.601. However, the GNRs were almost monodispersed and the absorbance decrease was only 0.289 for D-Cys. The combined assay process with the optical rotation of GNRs, and the chiral recognition phenomenon could be assigned to the fact that L-Cys induced the end-to-end assembly of GNRs through crosslinking agent Cu²⁺ ions. The detection limit of this method for L-Cys was 0.325 μM. The relative standard deviation (RSD) was 1.5% for trace L-Cys, which indicated that the method presented good precision for the analysis of trace L-Cys in solution samples. Futhermore, we demonstrated that the nanosensor possessed high selectivity for the chiral recognition of Cys enantiomers. The response of GNRs (ΔA_LD) to Cys enantiomers was 7.8 times to tryptophan (Try) enantiomers, and 9.2 times to phenylalanine (Phe) enantiomers. In our perception, the assay showed new opportunities for efficient enantiosensing strategies.