Anisotropic Growth in Three-Dimensional Plasmonic Networks for Ultrasensitive and Versatile SERS Platforms

Plasmonic nanostructures with engineered morphologies offer powerful platforms for plasmon-based catalysis and enhanced sensing by amplifying local electromagnetic fields, thereby significantly improving the sensitivity and detection limits of techniques such as surface-enhanced Raman scattering (SERS). However, constructing large-area, flexible, and highly sensitive 3D plasmonic platforms remains a significant challenge. Here, we report a bottom-up strategy to develop hard and flexible three-dimensional (3D) plasmonic platforms at ambient conditions via in situ growth of gold nanowires (AuNWs). Under the induction of 4-mercaptobenzoic acid (pMBA), the AuNWs showed anisotropic growth and formed interconnected 3D networks with high-density plasmonic hotspots, which generated strong localized surface plasmon resonance (LSPR) coupling, enhanced electromagnetic fields, and required analyte-accessible surface area. Such 3D plasmonic platform first displays ultrasensitive sensing of trace biogenic amine gases (BAs) with a detection limit as low as 10^-14 M in spoiled seafood through integrating into food packaging. Surely, our work provides a robust and scalable strategy for constructing 3D plasmonic networks for ultrasensitive and versatile SERS platforms, offering broad potential in real-time environmental monitoring, noninvasive smart packaging, and plasmon-assisted catalysis.