Patchy Nanoparticle Synthesis and Self-Assembly

Biological building blocks (i.e., proteins) are encoded with the information of target structure into the chemical and morphological patches, guiding their assembly into the levels of functional structures that are crucial for living organisms. Learning from nature, researchers have been attracted to the artificial analogues, “patchy particles,” which have controlled geometries of patches that serve as directional bonding sites. However, unlike the abundant studies of micron-scale patchy particles, which demonstrated complex assembly structures and unique behaviors attributed to the patches, research on patchy nanoparticles (NPs) has remained challenging. In the present chapter, we discuss the recent understandings on patchy NP design and synthesis strategies, and physical principles of their assembly behaviors, which are the main factors to program patchy NP self-assembly into target structures that cannot be achieved by conventional non-patched NPs. We further summarize the self-assembly of patchy NPs under external fields, in simulation, and in kinetically controlled assembly pathways, to show the structural richness patchy NPs bring. The patchy NP assembly is novel by their structures as well as the multicomponent features, and thus exhibits unique optical, chemical, and mechanical properties, potentially aiding applications in catalysts, photonic crystals, and metamaterials as well as fundamental nanoscience.

Self-Assembly of Nanoparticles Decorated by Liquid Crystalline Groups: Computer Simulations

We present the results of the computer simulations for the self-assembly of decorated nanoparticles. The models are rather generic and comprise a central core and a shell of ligands containing terminal liquid crystalline group, including the case of the azobenzene chromophores. The simulations are performed using the coarse-grained molecular dynamics with the effective soft-core interparticle interaction potentials obtained from the atomistic simulations. The discussion is centred around the set of the self-assembled morphologies in a melt of 100–200 of such decorated nanoparticles obtained upon the change of the temperature, surface density of ligands, the type of the terminal group attachment, as well as the prediction of the possibility of photo-assisted self-assembly of the nanoparticles decorated by the azobenzene chromophores.

Self-Assembly of GeMn Nanocolumns in GeMn Thin Films

This chapter presents the results of growing GeMn nanocolumns on Ge(001) substrates by means of molecular beam epitaxy (MBE). The samples have been prepared by co-depositing Ge and Mn at growth temperature of 130°C and Mn at concentration of ~6% to ensure the reproduction of GeMn nanocolumns. Based on the observation of changes in reflection high-energy electron diffraction (RHEED) patterns during nanocolumn growth, surface signals of GeMn nanocolumn formation have been identified. Structural analysis using transmission electron microscopy (TEM) show the self-assembled nanocolumns with core-shell structure extend through the whole thickness of the GeMn layer. Most of nanocolumns are oriented perpendicular to the interface along the growth direction. The nanocolumn size has been determined to be about 5–8 nm in diameter and a maximum height of 80 nm. A phenomenological model has been proposed to explain the driving force for self-assembly and growth mechanisms of GeMn nanocolumns. The in-plane or lateral Mn diffusion/segregation is driven by a low solubility of Mn in Ge while the driving force of Mn vertical segregation is induced by the surfactant effect along the [001] direction.

Self-Assembled Copper Polypyridyl Supramolecular Metallopolymer Achieving Enhanced Anticancer Efficacy

Metallopolymers, a combination of organic polymers and metal center, contain metal atoms in repeating monomers can change its dynamic and thermodynamic properties through the directionality of coordination bonds and chemical tailoring of ligands. In the past decade, self-assembled functional supramolecular metallopolymers have aroused a surge of research interest, and have demonstrated application potential in cancer therapy. In this chapter, we have summarized the progress in the rational design of biological application of different metallopolymers. Especially, a copper polypyridyl complex was found be able to self-assemble into a supramolecular metallopolymer driven by the intermolecular interactions, which could enhance the uptake in cancer cells through endocytosis, thus effectively inhibit tumor growth in vivo without damage to the major organs. This study may provide a good example to use self-assembled metallopolymer to achieve enhanced anticancer efficacy.