Shape-controlled asymmetric bowl-like PDA@Au substrates for sensitive SERS detection of anabolic androgenic steroids.

The widespread accumulation of androgenic steroid endocrine disruptors in water and food has garnered increasing attention due to their significant risks to ecosystems and human health. These steroids, which cannot be completely eliminated, highlight the urgent need for advanced detection technologies. In this study, we present a novel emulsion-induced interface-anisotropic assembly strategy to synthesize bowl-like mesoporous polydopamine (PDA) particles, which exhibit high sensitivity in surface-enhanced Raman scattering (SERS) detection. In-situ reduction of chloroauric acid leads to the formation of Au nanoparticles (NPs) on the PDA surface, where synergistic Au-N interactions enhance the SERS performance. The distinctive bowl-like structure generates abundant "hot spots" on both sides, resulting in exceptional sensitivity. The low relative standard deviation (RSD) values (<11.7 %) across different PDA@Au NPs, along with real sample analyses (1.9-4.0 %), confirm the high reproducibility and uniformity of the SERS substrates, all achieved without the use of additional reducing agents. This cost-effective and straightforward method eliminates the need for complex surface treatments, making it particularly suitable for real-time detection of anabolic steroids across various matrices. These findings underscore the potential of bowl-like PDA materials for broader applications in clinical diagnostics, environmental monitoring, and sports doping control.