Formation of an Isolated Spherical Three‐Dimensional Nanoparticle Assembly as Stable Submicrometer‐Sized Units by Using an Inorganic Wrapping Technique

Abstract

COMMUNICATIONSScheme 1. Schematic illustration of the novel assembly and wrapping technique used to generate submicrometer-sized titanium dioxide-coated gold nanoparticle 3D assemblies.

Size Control of Mesoscale Aqueous Assemblies of Quantum Dots and Block Copolymers

“…Metal and semiconductor nanoparticles offer unique size-tunable properties arising from quantum confinement and surface effects (e.g., photoluminescence, nonlinear optical properties, surface plasmon resonances). With a view to designing complex structures for applications ranging from biolabeling to photonics, a range of recent research efforts have focused on various self-assembly strategies to control the organization of nanoparticle building blocks in colloidal media. − In particular, a number of groups have developed methods of forming nanoparticle/polymer colloids in which mesoscale composite particles are assembled from multiple metal or semiconductor nanoparticles via a polymer component which can act as a scaffold, glue, or matrix. − To this end, supramolecular assembly of nanoparticle “bricks” and polymer “mortar”, − electrostatic assembly of nanoparticles on preformed polymer spheres, <...…”

Formation of Spherical Nanostructures by the Controlled Aggregation of Gold Colloids

“…Although several protocols exist to prepare gold nanoparticles that are stable enough to be robustly handled and chemically functionalized, − only a few cases of chemically controlled assembly of well-defined suprastructures containing two or more particles have been reported. − The main problem appears to be that the particles tend to aggregate in an uncontrolled manner because it is not usually possible to adjust precisely the number and spatial orientation of chemically reactive linker groups on the surface of the particles. An alternative to building up structures in a particle-by-particle fashion is to organize many particles simultaneously into self-assembled materials by a more global manipulation of their environment such as solvent evaporation, addition of a nonsolvent, freeze drying, or the presence of a template. − The appeal of controlling chemical reactivity and interparticle connectivity on the single-particle level notwithstanding, the latter strategy has, in comparison, yielded a larger range of new nanostructures with a host of potential applications including gas sensors, optical coatings, and information storage. , These strategies are based on polymer-based molecular recognition, , multidentate thioethers, − DNA linking, − ligand place exchange, hydrogen bonding, inorganic wrapping, and stepwise assembly. , In particular, Zhong and co-workers have recently demonstrated an elegant approach in a series of publications that show that spherical assemblies of gold nanoparticles can be prepared from solution by using specifically designed tridentate and tetradentate thioethers as mediators in the presence of a surfactant, tetraalkylammonium bromide, as a template. − The aggregates are stable for a few days, and their size can be controlled by the choice of template.…”

Emulsions-directed assembly of gold nanoparticles to molecularly-linked and size-controlled spherical aggregates

“…An important approach is to organize many particles simultaneously into self-assembled materials by a global manipulation of their environment such as solvent evaporation, addition of a nonsolvent, freeze drying, or the presence of a template [16][17][18][19][20][21][22][23]. Most of the other strategies are based on polymer-based molecular recognition [23,24], multidentate thioethers [25][26][27], DNA linking [1,9,14], ligand place exchange [11], hydrogen bonding [28], inorganic wrapping [29], and stepwise assembly [5,18]. In particular, Zhong and co-workers have demonstrated an elegant approach in a series of publications that show that dispersible spherical assemblies of gold nanoparticles can be prepared using multidentate thioethers in the presence of certain surfactants [17][18][19].…”