Dynamic hot spots engineering via tyramine-triggered AgAu Nanoassembly: A colloidal Interface strategy for ultrasensitive SERS detection of mycotoxins

The rational design of colloidal interfaces with spatiotemporal control over electromagnetic coupling is essential for enhancing the sensitivity of surface-enhanced Raman scattering (SERS) sensitivity. In this study, we propose a tyramine-triggered Ag Au nanoassembly strategy, driven by enzymatic polymerization-mediated interfacial engineering. The horseradish peroxidase/H₂O₂ system induces oxidative crosslinking of tyramine-functionalized Ag nanoparticles (Ag NPs), facilitating precise assembly with antigen-immobilized Au substrates to generate plasmonic architectures. Finite-difference time-domain simulations show that the Au Ag bilayer configuration exhibits enhanced electromagnetic field intensity compared to monolayer Au NPs or Ag NPs. This enhancement is attributed to synergistic interfacial coupling at the Au Ag nanogaps and intra-layer plasmon resonance. The dynamic nanoassembly achieved ultrasensitive aflatoxin B₁ detection with a limit of detection of 0.11 pg/mL, high interference resistance, and a wide dynamic range (0.001–100 ng/mL). The quantitative detection of AFB₁ in real samples demonstrates excellent accuracy (95.7–109.7 %) and precision (RSD < 7.5 %). By integrating enzymatic colloidal control with interfacial electromagnetic engineering, this work establishes a new paradigm for field-deployable mycotoxin monitoring in complex food systems.