Chiral plasmonic Au-Ag core shell nanobipyramid for SERS enantiomeric discrimination of biologically relevant small molecules

The identification of enantiomers is of great importance in chiral separations and medicinal chemistry. While Surface-enhanced Raman spectroscopy (SERS) is a technique that provides vibrational fingerprints of analytes. The enantiomers identification relies on the SERS difference between left and right-handed circularly polarized light or additional selectors for indirect distinction. In this work, Au-Ag core shell nanobipyramid (L/D-Au@Ag BPs) were synthesized guiding by chiral encoder of L/D-cysteine. L/D-Au@Ag BPs produced plasmon-induced circular dichroism signals in the plasmon resonance absorption band, which can be tuned by modulation the amount of cysteine. Moreover, the chiral anisotropy factor of L/D-Au@Ag BPs at 532 nm can reach 5.11 x 10-3. Due to the selective resonance coupling between L/D-Au@Ag BPs and different enantiomers, L/D-Au@Ag BPs were further used as SERS substrates for efficient discrimination of biologically relevant small molecules. Chiral Au@Ag BPs display the potential for chiral drug identification.

Automated summary

The identification of enantiomers is crucial in chiral separations and medicinal chemistry. Surface-enhanced Raman spectroscopy (SERS) is used to distinguish enantiomers by exploiting the SERS difference between left and right-handed circularly polarized light or additional selectors. In this study, L/D-Au@Ag core shell nanobipyramids were synthesized utilizing L/D-cysteine as a chiral encoder. These nanobipyramids exhibited plasmon-induced circular dichroism signals and could be tuned by adjusting the amount of cysteine. They were further used as SERS substrates for effective discrimination of biologically relevant small molecules, showing potential for chiral drug identification.