Facile Electroless Displacement Plating of Mesoporous Gold Films as Robust and Reproducible SERS Substrates for Biosensing

Abstract

Mesoporous gold and silver films on copper (Mp-Au/Cu and Mp-Ag/Cu) are fabricated via a micelle-templated electroless displacement deposition. This one-step, substrate-flexible method generates uniform, highly porous metallic films with excellent adhesion and scalability. Electron microscopy results reveal well-defined nanoscale pores with mean diameters of ~25 nm for Mp-Au/Cu and ~16 nm for Mp-Ag/Cu, resulting in large specific surface areas and densely distributed plasmonic hotspots. Structural analyses confirm nanocrystalline metallic domains and high purity of the mesoporous networks. The open porous architecture provides a stable and biocompatible interface, facilitating efficient immobilization of biomolecules and enabling functional bio-conjugation. As a proof-of-concept demonstration, Mp-Au/Cu films are employed as surface-enhanced Raman scattering (SERS) substrates for the detection of the pro-inflammatory cytokine interleukin-1β (IL-1β). The mesoporous framework promotes precise localisation of DTNB-encoded, antibody-conjugated SERS nanotags within plasmonic hotspots, producing intense and photostable Raman signals. The platform exhibits excellent reproducibility (RSD = 3.8%), nearly two-fold enhancement compared to flat Au controls, and a low detection limit of 17.6 pg/mL. Control experiments confirm high selectivity and minimal nonspecific binding. Collectively, these findings introduce Mp-Au/Cu as a robust, sensitive, and biofunctional plasmonic material capable of highly reproducible cytokine detection, providing a versatile foundation for next-generation biosensing and diagnostic technologies.