Protein-Assisted Assembly of Modular 3D Plasmonic Raspberry-like Core/Satellite Nanoclusters: Correlation of Structure and Optical Properties

Abstract

We present a bottom-up assembly route for a large-scale organization of plasmonic nanoparticles (NPs) into three-dimensional (3D) modular assemblies with core/satellite structure. The protein-assisted assembly of small spherical gold or silver NPs with a hydrophilic protein shell (as satellites) onto larger metal NPs (as cores) offers high modularity in sizes and composition at high satellite coverage (close to the jamming limit). The resulting dispersions of metal/metal nanoclusters exhibit high colloidal stability and therefore allow for high concentrations and a precise characterization of the nanocluster architecture in dispersion by small-angle X-ray scattering (SAXS). Strong near-field coupling between the building blocks results in distinct regimes of dominant satellite-to-satellite and core-to-satellite coupling. High robustness against satellite disorder was proved by UV/vis diffuse reflectance (integrating sphere) measurements. Generalized multiparticle Mie theory (GMMT) simulations were employed to describe the electromagnetic coupling within the nanoclusters. The close correlation of structure and optical property allows for the rational design of core/satellite nanoclusters with tailored plasmonics and well-defined near-field enhancement, with perspectives for applications such as surface-enhanced spectroscopies.

Zinc‐Coordinated Hierarchical Organization of Ligand‐Stabilized Gold Nanoclusters for Chiral Recognition and Separation

“…The path to hierarchical organization of nanoscale particles in liquid medium offers great opportunities for the development of new chemical methods of colloidal assembly . Additionally, sophisticated design provides superstructures with physicochemical properties, which are not only superior, but also do not arise in the constituent particles.…”

Progress and Opportunities in Soft Photonics and Biologically Inspired Optics

“…The term “soft photonics” refers primarily to the realization of photonic systems from various individual components such as gratings, photonic crystals, plasmonic structures, microlenses, and metamaterials, which are formed fully or partially from a broad range of soft materials. These materials include fluids, DNA assemblies, hydrogels, flexible and stretchable elastomers, photo‐reconfigurable polymers, biological components, and colloidal suspensions . They are processed using suitable soft matter processing strategies, including self‐assembly, reaction–diffusion processes, nanoimprinting/transfer printing,…”

Three-Dimensional SERS Substrates Formed with Plasmonic Core-Satellite Nanostructures

“…Although recent studies have demonstrated various kinds of core-satellite nanostructures, some of the studies only focus on the synthesis and plasmonic properties of the nanostructures but did not use the nanostructures for SERS 24,25,32,42–47 . Some other studies used core-satellite nanostructures for enhancing Raman reporter molecules that were placed at the hot spots but not for determining the concentrations of molecules 30,31,33,34,48–50 .…”