SERS-based Aptasensor using Au NSs@Ag NPs/magnetic graphene oxide assemblies for simultaneous detection of...

The rapid and simultaneous detection of multiple foodborne pathogens is crucial for public health and food safety. Here, a highly sensitive surface-enhanced Raman scattering (SERS) aptasensing platform was constructed using Raman reporter-labeled gold nanostars@silver core-shell nanoparticles (Au NSs@Ag NPs) and aptamer-functionalized magnetic graphene oxide (MGO) for the simultaneous detection of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). These materials (Au NSs@Ag NPs and MGO) were modified with specific aptamers, and the Au NSs@Ag NPs were loaded with distinct Raman reporters (ATP and NTP) to serve as SERS probes. In the presence of target bacteria, a sandwich complex is formed through Au NSs@Ag NPs aptamer-recognition-induced assembly on the MGO surface, enabling efficient magnetic separation and enrichment. Au NSs@Ag NPs embedded with ATP and NTP were employed to simultaneously quantify the two target bacteria based on their distinct SERS peaks. Due to the strong SERS enhancement of Au NSs@Ag NPs and the superior enrichment capacity of MGO, the proposed method exhibits excellent performance for the simultaneous quantification of both pathogens. The SERS intensity shows a good linear relationship with the logarithmic bacterial concentration ranging from 50 to 10⁶ CFU/mL, with detection limits as low as 16 CFU/mL for E. coli and 20 CFU/mL for S. aureus. This work provides a robust and efficient strategy for multiplex pathogen detection, with significant potential for applications in real food samples.