Nanoparticles of CdTe were found to spontaneously reorganize into crystalline nanowires upon controlled removal of the protective shell of organic stabilizer. The intermediate step in the nanowire formation was found to be pearl-necklace aggregates. Strong dipole-dipole interaction is believed to be the driving force of nanoparticle self-organization. The linear aggregates subsequently recrystallized into nanowires whose diameter was determined by the diameter of the nanoparticles. The produced nanowires have high aspect ratio, uniformity, and optical activity. These findings demonstrate the collective behavior of nanoparticles as well as a convenient, simple technique for production of one-dimensional semiconductor colloids suitable for subsequent processing into quantum-confined superstructures, materials, and devices.

The design of advanced, nanostructured materials at the molecular level is of tremendous interest for the scientific and engineering communities because of the broad application of these materials in the biomedical field. Among the available techniques, the layer‐by‐layer assembly method introduced by Decher and co‐workers in 1992 has attracted extensive attention because it possesses extraordinary advantages for biomedical applications: ease of preparation, versatility, capability of incorporating high loadings of different types of biomolecules in the films, fine control over the materials' structure, and robustness of the products under ambient and physiological conditions. In this context, a systematic review of current research on biomedical applications of layer‐by‐layer assembly is presented. The structure and bioactivity of biomolecules in thin films fabricated by layer‐by‐layer assembly are introduced. The applications of layer‐by‐layer assembly in biomimetics, biosensors, drug delivery, protein and cell adhesion, mediation of cellular functions, and implantable materials are addressed. Future developments in the field of biomedical applications of layer‐by‐layer assembly are also discussed.

In their physical dimensions, surface chemistry, and degree of anisotropic interactions in solution, CdTe nanoparticles are similar to proteins. We experimentally observed their spontaneous, template-free organization into free-floating particulate sheets, which resemble the assembly of surface layer (S-layer) proteins. Computer simulation and concurrent experiments demonstrated that the dipole moment, small positive charge, and directional hydrophobic attraction are the driving forces for the self-organization process. The data presented here highlight the analogy of the solution behavior of the two vastly different classes of chemical structures.

Nanoparticle (NP) assemblies are of considerable interest for both fundamental research and applications, since they provide direct bridges between nanometer‐scale objects and the macroscale world. Unlike two‐dimensional or three‐dimensional NP assemblies, which have been extensively studied and reviewed, reports on one‐dimensional (1D) NP assemblies are rather rare, even though these assemblies are likely to play critical roles in the improvement of the efficiencies of various electronic, optoelectronic, magnetic, and other devices based on single NPs or their composites. Additionally, 1D assemblies of NPs, i.e., chains, can significantly help in the understanding of a number of biological processes and fundamental quantum mechanics of nanometer‐scale systems. The difficulties are very evident when one wants to realize anisotropic 1D assemblies from presumably isotropic, zero‐dimensional NPs. In this context, the authors present a systemic review of current research on 1D NP assemblies. Their preparation methods are classified and novel characteristics of NP chains, such as collective properties and directional transfer of photons, electrons, spins, etc., are elucidated. Current problems underlying the fundamental research and practical applications of 1D NP assemblies are also addressed.

More than just an empty shell: Multishelled Co3O4 microspheres were synthesized as anode materials for lithium‐ion batteries in high yield and purity. As their porous hollow multishell structure guarantees a shorter Li+ diffusion length and sufficient void space to buffer the volume expansion, their rate capacity, cycling performance, and specific capacity were excellent (1615.8 mA h g−1 in the 30th cycle for triple‐shelled Co3O4; see graph).

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Noble-metal nanoparticles (NPs) (such as Au, Ag, Pd, and Pt) have been the subject of intense research because their unique physiochemical properties are different from those of their bulk counterparts [1] and various applications are anticipated in sensing, [2] imaging, [3] cancer therapy, [4] optical data storage, [5] and catalysis. [6] However, it is well known that free noble-metal NPs have high surface energies and tend to aggregate and fuse; as a result the intriguing properties observed for the NPs disappear and difficulties arise for longterm storage, processing, and applications. Therefore, great efforts have been devoted to develop novel strategies to stabilize NPs, [7] and the most common approach is to coat noble-metal NPs with either organic or inorganic shells. These shells not only endow NPs with high stability but also offer them additional functionalities. As an example, in addition to good stability and biocompatibility, the mesoporous silica shells that are currently broadly used have high surface area and tunable pore size and volume, which can accommodate analytes and drug molecules. [7, 8] Unfortunately, the amorphous structure of silica and its own characteristics determine that it may be used only as a carrier, stabilizer, and ligand linker. In order to break through the limitations and develop a wide range of applications, it is necessary to search for new types of shell materials that not only have properties similar to those of porous silica but also impart new functionalities.In addition to high specific surface area and tunable pore size and volume, metal-organic frameworks (MOFs) have many exciting characteristics including structural adaptivity and flexibility, ordered crystalline pores, and multiple coordination sites, and offer various functions such as chemical separation, [9] gas storage, [10] drug delivery, [11] sensing, [12] and catalysis, [13] which originate from the limitless choice of building blocks. [14] Recently, MOFs have been used as functional materials to fabricate nanostructures with noble-metal NPs by either embedding NPs in the MOF matrices or encapsulating NPs within the MOF layers. [15] Nevertheless, effective control over the dispersibility of NPs within MOFs as well as the morphology and size of the composite products still presents significant challenges. For example, to our knowledge, there are few reports about the construction of well-defined core-shell noble-metal@MOF NPs, [15f,g] and none on the successful synthesis of core-shell noble-metal@-

This paper reports a versatile seed-mediated growth method for selectively synthesizing single-crystalline rhombic dodecahedral, octahedral, and cubic gold nanocrystals. In the seed-mediated growth method, cetylpyridinium chloride (CPC) and CPC-capped single-crystalline gold nanocrystals 41.3 nm in size are used as the surfactant and seeds, respectively. The CPC-capped gold seeds can avoid twinning during the growth process, which enables us to study the correlations between the growth conditions and the shapes of the gold nanocrystals. Surface-energy and kinetic considerations are taken into account to understand the formation mechanisms of the single-crystalline gold nanocrystals with varying shapes. CPC surfactants are found to alter the surface energies of gold facets in the order {100} > {110} > {111} under the growth conditions in this study, whereas the growth kinetics leads to the formation of thermodynamically less favored shapes that are not bounded by the most stable facets. The competition between AuCl(4)(-) reduction and the CPC capping process on the {111} and {110} facets of gold nanocrystals plays an important role in the formation of the rhombic dodecahedral (RD) and octahedral gold nanocrystals. Octahedral nanocrystals are formed when the capping of CPC on {111} facets dominates, while RD nanocrystals are formed when the reduction of AuCl(4)(-) on {111} facets dominates. Cubic gold nanocrystals are formed by the introduction of bromide ions in the presence of CPC. The cooperative work of cetylpyridinium and bromide ions can stabilize the gold {100} facet under the growth condition in this study, thereby leading to the formation of cubic gold nanocrystals.