Ag/UiO-66-Decorated 3D-Printed Slippery Liquid-Infused Porous Surfaces for Ultrasensitive SERS Detection

Surface-enhanced Raman scattering (SERS) holds significant potential for rapid food safety screening; however, its application is often constrained by substrate sensitivity, stability, and cost. Here, we developed a multifunctional SERS substrate by integrating a 3D-printed microstructured template with a slippery liquid-infused porous surface (SLIPS) and Ag/UiO-66 metal–organic framework (MOF) nanoparticles for food safety monitoring. The nearly pinning-free SLIPS interface enabled evaporation-driven enrichment of nanoparticles at microcone tips, generating dense, spatially confined hotspots with an enhancement factor (EF) of 1.44 × 108. The Ag/UiO-66@SLIPS substrate demonstrated ultrasensitive SERS detection of illicit sildenafil (SD) and food-dye additives (using rhodamine 6G as a model). The substrate achieved limits of detection (LOD) for SD of 100 pg/mL (2.11 × 10–10 M) in ethanol and 1 ng/mL (2.11 × 10–9 M) in health wine using only 10 μL samples. For rhodamine 6G (R6G), an ultralow LOD of 1 fg/mL (2.09 × 10–15 M) was obtained. Furthermore, for photocatalytically degradable dyes, the inherent catalytic activity of Ag/UiO-66 provided a self-cleaning pathway to mitigate signal carryover and enabled repeated measurements. The substrate maintained 83.5% signal intensity over 150 days and can be refreshed for continued use. This work combines biomimetic structures with functionalized nanomaterials, enabling the simple, cost-effective development of robust, uniform SERS substrates for multiscenario trace molecular sensing in food safety.