Aggregation-Driven Controllable Plasmonic Transition of Silica-Coated Gold Nanoparticles with Temperature-Dependent...

Localized surface plasmon resonance (LSPR) effect relies on the shape, size, and dispersion state of metal nanoparticles and can potentially be employed in many applications such as chemical/biological sensor, optoelectronics, and photocatalyst. While complicated synthetic approaches changing shape and size of nanoparticles can control the intrinsic LSPR effect, here we show that controlling interparticle interactions with silica-coated gold nanoparticles (Au@SiO₂ NPs) is a powerful approach, permitting wide range of optical bandwidth of gold nanoparticles with great stability. The interparticle interactions of Au@SiO₂ NPs are controlled through concentration-, temperature-, and time-dependent polymer-induced interactions. The polymer-induced interactions modulate the state of particle dispersion, resulting an effective plasmonic shift by more than 200 nm. We further explore the microstructure of particle aggregation and explain mechanisms of plasmonic shift based on the results of small-angle X-ray scattering (SAXS) and discrete dipole approximation (DDA) calculation. We show that an effective control of LSPR behavior is now available through trapped aggregation of Au@SiO₂ NPs with temperature variation. We anticipate that the suggested strategy can be employed in many practical applications such as optical bioimaging and optoelectronic devices.