Design and fabrication of Zn@ZnO@Ag chip for Raman scattering analysis of norfloxacin in liquid milk, fish and animal feeds

A novel and easy-to-prepare plasmonic nanoparticles doped semiconductor substrate—Zn@ZnO@Ag chip with ultra-high surface-enhanced Raman scattering (SERS) activity was fabricated for label-free, rapid and sensitive analysis of norfloxacin. The Zn@ZnO array was synthesized by surface oxidation at low temperature, followed by in-situ reduction to form leaf-like AgNPs on Zn@ZnO array without extra reducing agent, thus fabricating a Zn@ZnO@Ag chip. The ultra-high SERS activity is attributed to the synergistic effect of semiconductor characteristics of ZnO and surface plasmon resonance properties of leaf-like AgNPs. The possible enhancement mechanism was verified by density functional theory simulations. The proposed SERS method showed a wide linear range (3.0–500.0 μg/L) and low limit of detection (0.8 μg/L) for norfloxacin analysis. High sensitivity, good selectivity and acceptable recoveries (82.7–113.6%) in real sample analysis were obtained. This study offers a promising SERS chip-based platform for norfloxacin detection in the field.