A Chiral Sensing System Based on Single Au Nanowire: A General SERS Strategy for Identification of the Enantiomers and Mechanism for Chiral Interaction

Enantiomers are a widespread phenomenon in chemistry, and the identification, separation, and synthesis of enantiomers were important in the fields of drug screening, disease diagnosis, and environmental monitoring. Herein, a new strategy was presented to recognize enantiomers based on the surface-enhanced Raman scattering (SERS) technique using a single Au nanowire (Au NW) decorated by Ag core-Au satellite nanocomposites as a new platform. The SERS discrimination detection of enantiomers is based on molecular interactions between chiral targets and this chiral Au NW-based nanosensor: the SERS signals of l-nanosensor can be enhanced by d-targets but decreased by l-targets. In contrast, the SERS signals of the d-nanosensor can be enhanced by l-targets but decreased by d-targets. Therefore, a new SERS method can be established for the detection of different enantiomers with high selectivity and sensitivity. A variety of chiral molecules, including glucose, threonine, mandelic acid, phenylalanine, sorbitol, tartaric acid and tryptophan, were successfully identified using this system, and the chiral recognition mechanism of this nanosensor was also explored in depth via the density functional theory (DFT) calculation. Due to the small overall dimension of single Au NW-based nanosensor, this method provides a facile and universal solution for online analysis and noninvasive diagnosis, especially for some confined environment and single-cell analysis.