Bayberry-Shaped Au–Ag NPs/PET as Flexible SERS Substrate for Ultrasensitive SERS Detection of Aflatoxin B1

The activity of flexible SERS substrates for aflatoxin B1 (AFB1) detection remains limited, stemming from challenges in the morphological control of active nanostructures. This study proposes a seed-mediated strategy for the simple and controllable synthesis of flexible Au–Ag NPs/PET substrates. By controlling the purity and size of the seeds, the morphology of the Au–Ag NPs can be tuned, providing a novel approach for the morphological control of Au–Ag NPs. Furthermore, the bayberry-like Au–Ag NPs/PET was used as an active substrate for SERS detection of AFB1 in milk. The substrate demonstrated excellent sensitivity. Notably, the bayberry-like Au–Ag NPs/PET enabled the rapid and quantitative detection of AFB1 over a concentration range from 10 −6 M to 10 −14 M. Clearly, the fabricated flexible bayberry-like Au–Ag NPs/PET holds considerable potential for applications in dairy product safety monitoring.