Surface engineering of SERS nanocomposites via metal–phenolic networks for stable sensing

Surface-enhanced Raman scattering spectroscopy (SERS) enables ultrasensitive and multiplexed detection, but unstable interfacial chemistry limits its reliability in complex environments. We introduce metal-polyphenol networks (MPNs) as a universal coating for stabilizing diverse SERS substrates. In a one-step aqueous co-assembly, tannic acid, Fe 3+ ions, and Raman reporters rapidly (<1 min) form uniform MPN shells on plasmonic and semiconducting nanostructures without additional surface pretreatment. The coatings offer tunable nanogap, Raman intensity enhancement, and maintain signal stability under physiological conditions. Optimized thickness (∼8 nm) maximizes enhancement factors and reporter loading, supporting applications from sensing to therapy. The intrinsic photothermal properties of MPNs enable antibacterial therapy against methicillin-resistant Staphylococcus aureus . These results establish MPN coatings as a substrate-independent, bioactive, and multifunctional strategy for robust SERS nanocomposites sensing in complex biological environments.