Controllable growth of Au NBPs@Ag nanorods modified PDMS as SERS substrate for rapid detection of malachite green in aquatic products

Raman studies have consistently emphasized the precise detection of target analytes by strategically manipulating the morphology and structure of noble metal nanomaterials. In this study, the nanorods with Ag shell and Au nanobipyramid core (Au NBPs@Ag) were designed and prepared through the weting chemcial method. The length of the nanorods can be adjusted from 131 ± 8 nm to 165 ± 23 nm by controlling the amount of Ag precursor, while keeping their width constant. According to the size of Au NBPs@Ag nanorods, surface-enhanced Raman scattering (SERS) performance would change significantly, and the optimal signal response was achieved when the aspect ratio of Au NBPs@Ag nanorods was 4.43. This can be due to the synergistic effect of gold core and silver shell changed by nanorods morphology, which further affected SERS performance. Moreover, Au NBPs@Ag modified polydimethylsiloxane (PDMS) flexible substrate was developed through interface self-assembly technology, allowing for sampling on irregular surfaces. The flexible SERS substrate was successfully applied to detect malachite green in contaminated river bass with wide linear range from 0.1 nM to 10 μM and detection limit of 0.1 nM. These results indicated that Au NBPs@Ag nanorods SERS substrate had great potential in the rapid trace detection of environmental detection and food safety.