Chiral Au nanostars for SERS sensing of enantiomers discrimination, multibacteria recognition and photothermal antibacterial application

The recognition and detection of chirality is of great significance in the fields of chemistry, pharmacy and biomedicine. In this work, we fabricated a chiral Au nanostars (C-AuNSs) with intense chiroptical responses and surface-enhanced Raman scattering (SERS) features by controlling chiral ligand D-/L-cysteine (Cys) concentration. The proposed chiral AuNSs can be applied for the enantiodiscrimination of amino acid based on SERS-chiral anisotropy (SERS-ChA) effect, in which homochiral amino acid has distinct affinities to the C-AuNSs of homogeneous handedness. By demonstrating selective affinity of D-AuNSs with D-glutamic acid (D-Glu) on bacterial peptidoglycan, we further realized effective identification of multiple bacteria according to SERS specific bacterial "fingerprints" by discriminant analysis (DA). More importantly, D-AuNSs can also be carried out to classify two bacterial pathogens (E. coli and S. aureus) in serum samples, as well as differentiate the infected patients from healthy subjects successfully with great accuracy. Benefiting from intrinsic photothermal capability, chiral AuNSs exhibited high efficiency in killing of bacteria and disrupting of biofilms through a synergistic chemotherapy and phototherapy (PTT) functions. Altogether, the chiral AuNSs provides a novel strategy for SERS discrimination of enantiomer and bacteria, as well as incorporation of photothermal bacterial elimination, contributing to further broaden the chiral nanomaterials-based application.