Advanced Bacterial Detection with SERS-Active Gold- and Silver-Coated Porous Silicon Nanowires

—Rapid and accurate bacterial identification plays a crucial role across diverse sectors, offering valuable applications. While traditional culture and molecular techniques maintain a high standard, the contemporary demand for diagnostics centers on swiftly delivering dependable insights into bacterial infections, directly at the site, within a short timeframe. In this study, we present a novel approach utilizing surface-enhanced Raman scattering (SERS)-active nanostructured substrates in the form of gold- and silver-coated porous silicon nanowires (AuAg@pSiNWs) for rapid and highly sensitive bacterial detection. The porous silicon nanowires are fabricated using a straightforward method known as metal-assisted chemical etching. Subsequently, silver and gold decoration is achieved through chemical reduction of metal salts, imbuing the substrates with SERS-active properties. Scanning electron microscopy data reveals that upon incubation with AuAg@pSiNWs, bacteria are localized amidst clusters and on the surface of the nanowires, particularly in the vicinity of bimetallic gold and silver nanoparticles. Illustrated through the utilization of Listeria innocua bacteria as a model, the SERS efficacy of AuAg@pSiNWs is highlighted, enabling rapid label-free bacterial diagnosis with a limit of detection of 1.14 × 10 4 CFU/mL.