Tailoring shell thickness in Au@Cu₂O nanoparticles for enhanced mimetic peroxidase activity: a colorimetric...

Zearalenone (ZEN), a prevalent mycotoxin in agricultural crops, poses significant risks to human and animal health due to its bioaccumulation potential within the food chain. In this study, Au@Cu₂O core-shell nanoparticles with precisely controlled Cu₂O shell thickness were synthesized through a gold nanoparticle (AuNPs)-mediated self-assembly strategy by modulating the amount of AuNPs. Systematic analysis revealed an inverse correlation between peroxidase-like activity and shell thickness. Consequently, a high-sensitivity colorimetric aptasensor for ZEN detection was developed via the integration of Au@Cu₂O nanoparticles with ZEN-specific aptamers. The Au@Cu₂O nanoparticles function as signal amplifiers, while the aptamers provide target specificity. Under optimal conditions, the aptasensor demonstrated a linear dynamic range of 0.0005-5 μg/L for ZEN, with colorimetric signal intensities exhibiting exceptional specificity for ZEN, with negligible cross-reactivity to co-occurring mycotoxins (AFB₁, AFB₂, OTA, DON, T-2), while achieving stable detection in real agricultural matrices, including wheat flour and cornmeal. Hence, this work not only offers a novel strategy for ZEN monitoring in food but also advances the rational design of core-shell nanomaterials for biosensing applications.