Self-Assembled Large-Area Chiral Plasmonic Gold Nanoparticle Films for Highly Enhanced Enantiomer Recognition

Surface-enhanced Raman scattering (SERS) utilizing chiral plasmonic nanoparticles presents a promising approach for chiral molecule detection yet is often hindered by substrate instability and signal inhomogeneity. Herein, an innovative strategy for fabricating highly uniform SERS substrates based on chiral gold (Au) rhombic dodecahedra is introduced. Well-defined chiral Au nanoparticles are synthesized via structural distortion modulation within a cysteine-induced synthesis system. These nanoparticles are subsequently assembled into large-area, high-density chiral nanofilms using a two-phase interfacial self-assembly technique. The resulting films generate a uniform super chiral field through plasmon-exciton coupling, enabling highly sensitive SERS discrimination of amino acid enantiomers (e.g., phenylalanine and tyrosine) under 532 nm excitation. Crucially, the chiral Au nanofilms exhibit a significant Raman intensity difference (DI ≈ 5) between d and l enantiomers, with intensity demonstrating a strong linear correlation (R² ≥ 0.97) to the enantiomeric excess (ee) value. This approach effectively overcomes the uniformity limitations of traditional randomly distributed SERS substrates, providing a robust theoretical foundation and technical pathway for developing highly sensitive, cost-effective chiral molecular recognition devices with significant potential in drug analysis, food safety, and biosensing.