Morphology-engineered Au@Ag nanocubes on eggshell membrane: A new strategy for constructing high-performance SERS substrate

Surface-enhanced Raman scattering (SERS) has widespread applications for sensitive detection due to its non-destructive nature, but is still limited by the lower signal sensitivity and reproducibility caused by uncontrolled hotspot distribution on substrates. To address this challenge, a reliable and highly sensitive SERS substrate was developed by in-situ fabrication of well-defined Au-core Ag-shell nanocubes (Au@Ag NCs) on eggshell membrane (ESM-Au@Ag). Notably, the precisely controlled size and morphology of Au@Ag NCs by tuning the synthesis conditions led to significantly enhanced SERS performance. The obtained ESM-Au@Ag exhibited remarkable SERS activity, excellent signal reproducibility, and good stability for crystal violet (CV) detection, achieving an ultralow limit of detection of 1.0 × 10⁻ 10 mol·L −1 and a high analytical enhancement factor of 1.6 × 10 8 . Finite-difference time-domain (FDTD) simulations revealed that this superior performance originates from the significantly localized electromagnetic field enhancement at the sharp edges/corners of the nanocubes, along with their uniform distribution on ESM substrate. Furthermore, the ESM-Au@Ag also showed high sensitivity toward multiple analytes, including Rhodamine 6 G, trinitrophenols, and adenine, indicating its potential for practical applications in environmental monitoring, food safety, clinical diagnosis, and public security. This work opens up a new avenue for designing high-performance SERS substrates with exceptional sensitivity, reproducibility, and stability.