Template-assisted assembly of structurally diverse plasmonic nanoparticle chains

One-dimensional (1D) plasmonic nanoarchitectures have attracted substantial interest owing to their highly tunable plasmonic properties, optical responses to the long-wavelength region, and directional light propagation. However, fabricating finite 1D chains with diverse geometries remains challenging. Here, we report an anodic aluminum oxide (AAO) template-mediated strategy to assemble plasmonic metal nanoparticles (NPs) into 1D nanochains. By promoting the hydrophilicity of the AAO channels via H₂O₂ treatment, we achieved uniform and dense pore filling with metal NPs, which could then be isolated in high yield after template removal. The length of the 1D NP chains could be controlled by adjusting the pore depth of the AAO template. This method is applicable to plasmonic NP building blocks with diverse shapes, sizes, and compositions. The resulting 1D NP chains exhibited shape- and geometry-dependent plasmonic features. Furthermore, our approach can be extended to realize 1D peapod-like architectures consisting of a plasmonic 1D NP chain core encapsulated within a plasmonic metal shell. This work presents a facile and versatile route for engineering 1D plasmonic nanoarchitectures with programmable geometries and tailored optical functions.