A hierarchical three-dimensional SERS substrate for trace pesticide residue detection

Pesticide residues detection is critical for protecting health and food quality. Surface-enhanced Raman scattering (SERS) has become a highly effective technique for pesticide analysis, with substrate performance largely dependent on material structure and surface properties. This study developed a three-dimensional hierarchical SERS substrate composed of fluorinated silver nanoparticles@titanium dioxide nanorods@silicon pyramids (F-Ag NPs @TiO₂ NRs@py-Si). This design synergistically combines efficient light capture by py-Si, high surface area of TiO₂ NRs, and strong localized surface plasmon resonance from Ag NPs, enhancing light energy utilization, hotspot density, and electromagnetic enhancement. The hydrophobic surface promotes analyte enrichment and enhances detection sensitivity. The substrate exhibited good reproducibility with RSDs ≤6.09%. The limit of detection of 10^-8 M was achieved for carbaryl, thiram, and thiabendazole in fruit extracts. This hierarchical substrate offers a promising approach for ultrasensitive pesticide residue detection in complex food matrices and advances the practical application of SERS in food safety.