Gold nanoparticles with helical surface structure transformed from chiral molecules for SERS-active substrates preparation.

Surface-enhanced Raman scattering (SERS) technique has enlarged the application of Raman spectroscopy, and the most crucial problem is the exploration of SERS-active materials. In the paper, a SERS substrate made of helical gold nanoparticles by the directed synthesis of L-glutathione (L-GSH) was proposed. Because of the large surface specific area and the uneven conduction electrons distribution for sharp tips resulted from the complex concave surface and the symmetry breaking structure, The nanostructure has shown an impressive average enhancement factor (EF) of 2.95 × 10 under off-resonant condition. This phenomenon was explained by the experimental results and finite difference time domain (FDTD) method. Finally, the SERS substrates were used to detect thiram on pear with a limit of detection (LOD) of 0.62 mg/kg and R of 0.9772. The proposed SERS substrates suggest the potential application of chiral molecules such as amino acids, peptides et al. in the SERS-active materials fabrication.