Rational design of nanoscale building blocks: silver and gold D5h nanostructures for sensing applications

Nanostructure design is a way of developing nanoscale building blocks with end functions in mind. The rational design pathway starts with the desired applications, assessing required properties for such applications, and then... [ view full abstract ]

Nanostructure design is a way of developing nanoscale building blocks with end functions in mind. The rational design pathway starts with the desired applications, assessing required properties for such applications, and then realizing those properties through nanoparticle synthesis. Noble metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) that has proven advantageous in sensing applications such as surface plasmon resonance (SPR) spectroscopy and surface enhanced Raman spectroscopy (SERS). Desirable properties for these applications include sharp LSPR peaks and high stability for SPR, and structures with regular cavities by non-close packing (creation of hot spots in film preparation) and cavitation (creation of hot spots within nanostructures) for SERS. All of these properties can be achieved with silver and gold D_5h (decahedral) nanoparticles. Silver decahedral nanoparticles (AgDeNPs) are first prepared with low size dispersity (sharp LSPR peaks) and then used as seeds for gold plated/shell, bimorphic and star morphologies. Synthesis and LSPR tuning of these nanostructures will be presented, as well as preliminary testing in SPR and SERS. Briefly, the nanomole detection of halides using SPR, and 10⁷ enhancement with near monolayer films in SERS have been reliably achieved.