Bioinspired synthesis and preparation of multilevel micro/nanostructured materials

In this review, some living organisms with multilevel hierarchical micro/nanostructures and related special properties are briefly introduced. The unique properties of organisms are mostly related to their special hierarchical micro/nanostructures. Inspired by nature, many zero-dimensional and one-dimensional micro/nanomaterials with biomimic or bioinspired multilevel micro/nanostructures have been successfully synthesized and prepared in recent years. Compared with traditional solid materials, the synthesis and preparation of these multilevel structured materials is more ingenious. Moreover, these kinds of multilevel micro/nanomaterials show fantastic properties in many fields because of their micro/nanoscale complex interior structures, whichmay be intended for application in catalysis, Li-ion batteries, biomedicines, sensors, and others.     

Nanoscale metal-organic materials

Metal-organic materials are found to be a fascinating novel class of functional nanomaterials. The limitless combinations between inorganic and organic building blocks enable researchers to synthesize 0- and 1-D metal-organic discrete nanostructures with varied compositions, morphologies and sizes, fabricate 2-D metal-organic thin films and membranes, and even structure them on surfaces at the nanometre length scale. In this tutorial review, the synthetic methodologies for preparing these miniaturized materials as well as their potential properties and future applications are discussed. This review wants to offer a panoramic view of this embryonic class of nanoscale materials that will be of interest to a cross-section of researchers working in chemistry, physics, medicine, nanotechnology, materials chemistry, etc., in the next years.     

Functional supramolecular assemblies derived from dendritic building blocks

Control of the structure and function of self-assembled materials has been a significant issue in many areas of nanoscience. Among many different types of building blocks, dendritic ones have shown interesting self-assembly behaviour and functional performances due to their unique shape and multiple functionalities. Dendritic building blocks exhibit unique self-assembly behaviour in diverse environments such as aqueous and organic solutions, solid-liquid interfaces, and thermotropic solid conditions. Tuning the balance between hydrophilic and hydrophobic parts, as well as the external conditions for self-assembly, provides unique opportunities for control of supramolecular architectures. Furthermore, the introduction of suitable functional moieties into dendrons enables us to control self-assembly characteristics, allowing nanostructures to exhibit smart performances for electronic or biological applications. The self-assembly characteristics of amphiphilic dendrons under various conditions were investigated to elucidate how dendrons can assemble into nanoscopic structures and how these nanoassemblies exhibit unique properties. Well-defined nanostructures derived from self-assembly of dendrons provide an efficient approach for exhibition of unique functions at the nanoscale. This feature article describes the unique self-assembly characteristics of various types of dendritic building blocks and their potential applications as advanced materials.     

Peptide-Based Optical/Electronic Materials: Assembly and Recent Applications in Biomedicine,Sensing, and Energy Storage

The unique optical and electronic properties of living systems are impressive. Peptide-based supramolecular self-assembly systems attempt to mimic these properties by preparation optical/electronic function materials with specific structure through simple building blocks, rational molecular design, and specific kinetic stimulation. From the perspective of building blocks and assembly strategies, the unique optical and electronic properties of peptide-based nanostructures, including peptides self-assembly and peptides regulate the assembly of external function subunits, are systematically reviewed. Additionally, their applications in biomedicine, sensing, and energy storage are also highlighted. This bioinspired peptide-based function material is one of the hot candidates for the new generation of green intellect materials, with many advantages such as biocompatibility, environmental friendliness, and adjustable morphology.     

Hybrid Soft Nanomaterials Composed of DNA Microspheres and Supramolecular Nanostructures of Semi-artificial Glycopeptides

Aqueous hybrid soft nanomaterials consisting of plural supramolecular architectures with a high degree of segregation (orthogonal coexistence) and precise hierarchy at the nano- and microscales, which are reminiscent of complex biomolecular systems, have attracted increasing attention. Remarkable progress has been witnessed in the construction of DNA nanostructures obtained by rational sequence design and supramolecular nanostructures of peptide derivatives through self-assembly under aqueous conditions. However, orthogonal self-assembly of DNA nanostructures and supramolecular nanostructures of peptide derivatives in a single medium has not yet been explored in detail. In this study, DNA microspheres, which can be obtained from three single-stranded DNAs, and three different supramolecular nanostructures (helical nanofibers, straight nanoribbons, and flowerlike microaggregates) of semi-artificial glycopeptides were simultaneously constructed in a single medium by a simple thermal annealing process, which gives rise to hybrid soft nanomaterials. Fluorescence imaging with selective staining of each supramolecular nanostructure uncovered the orthogonal coexistence of these structures with only marginal impact on their morphology. Additionally, the biostimuli-responsive degradation propensity of each supramolecular architecture is retained, and this may allow the construction of active soft nanomaterials exhibiting intelligent biofunctions.     

Nanorattles or Yolk–Shell Nanoparticles—What Are They,How Are They Made,and What Are They Good For?

The development of nanotechnology has led to the design of cutting‐edge nanomaterials with increasing levels of complexity. Although “traditional” solid, uniform nanoparticles are still the most frequently reported structures, new generations of nanoparticles have been constantly emerging over the last several decades. The outcome of this nano‐art extends beyond nanomaterials with alternative compositions and/or morphologies. The current state‐of‐the‐art allows for the design of nanostructures composed of different building blocks that exhibit diverse properties. Furthermore, those properties can be a reflection of either individual features, which are characteristic of a particular building block alone, and/or synergistic effects resulting from interactions between building blocks. Therefore, the unique structures as well as the outstanding properties of nanorattles have attracted increasing attention for possible biomedical and industrial applications. Although these nanoparticles resemble core–shell particles, they have a distinctive feature, which is a presence of a void that provides a homogenous environment for the encapsulated core. In this Review, we give a comprehensive insight into the fabrication of nanorattles. A special emphasis is put on the choice of building blocks as well as the choice of preparation method, because those two aspects further influence properties and thus possible future applications, which will also be discussed.     

Elementary building blocks of self-assembled peptide nanotubes

In the world of biology, "self-assembly" is the ability of biological entities to interact with one another to form supramolecular structures. One basic group of self-assembled structures is peptide nanotubes (PNTs). However, the self-assembly mechanism, with its special characteristics, is not yet fully understood. An exceptional quantum-confined approach is shown here for the self-assembly mechanism in bio-inspired materials. We found the elementary building block of the studied PNT, which is self-assembled from short peptides composed of two phenylalanine residues, to be 0D-quantum-confined (can be related to confinement in 3D), also called a quantum dot (QD). This elementary building block can further self-assemble to a PNT formation. It has been observed that the assembly process of dots to tubes and the disassembly process of tubes to dots are reversible. We further show that a similar dipeptide can also self-assemble to a QD-like structure, with different dimensions. The presented peptide QD structures are nanometer-sized structures, with pronounced exciton effects, which may promote the use of an entirely new kind of organic QDs.     

Shape-controllable Synthesis of Functional Nanomaterials on DNA Templates

DNA nanotechnology enables precise organization of nanoscale objects with extraordinarily structural programmability.Self-assembled DNA nanostructures possess a lot of interesting features,such as designable size and shape,and structural addressability at nanometer scale.Taking advantage of these properties,DNA nanostructures could work as templates or molds for the controllable synthesis of functional nanomaterials,such as organic macromolecules,metallic or inorganic nonmetallic nanomaterials.In this review,we summarize the recent progress in the shape-controllable synthesis of functional nanomaterials on DNA templates.The potential application fields of these nanomaterials are also discussed.     

Collective buckling of a two-dimensional array of nanoscale columns

Periodic soft nanostructures are building blocks for small devices. However, mechanical failure in the form of structure buckling or distortion from their original shape is often reported when the dimension of these soft structures were reduced to below submicron scale. Such a phenomenon seriously limits a reliable impact of these nanostructures to greater applications. Current understandings of buckling of soft 2-D nanostructures are limited. The substrate for these soft nanostructures is usually very compliant. Neighboring nanostructures could interact through the deformation of the substrate. We analyze the collective buckling of a two-dimensional array of nanoscale columns with their lower ends built into an elastic substrate. Buckling of these nanostructures is mathematically described by an eigenvalue problem. Numerical analyses show patterned collapse for these 2-D nanostructures, qualitatively matching reported experimental findings. Our efforts are useful toward the understanding and manufacturing of many two-dimensional nanoscale features.     

Effect of the peptide secondary structure on the peptide amphiphile supramolecular structure and interactions

Bottom-up fabrication of self-assembled nanomaterials requires control over forces and interactions between building blocks. We report here on the formation and architecture of supramolecular structures constructed from two different peptide amphiphiles. Inclusion of four alanines between a 16-mer peptide and a 16 carbon long aliphatic tail resulted in a secondary structure shift of the peptide headgroups from α helices to β sheets. A concomitant shift in self-assembled morphology from nanoribbons to core-shell worm-like micelles was observed by cryogenic transmission electron microscopy (cryo-TEM) and atomic force microscopy (AFM). In the presence of divalent magnesium ions, these a priori formed supramolecular structures interacted in distinct manners, highlighting the importance of peptide amphiphile design in self-assembly.     

Complex vesicle-based structures

Making nanotechnology practical is a challenge for modern research. Self-assembly is clearly going to be a necessary tool to realize practical and economic nanoscale structures. A biomimetic approach to the self-assembly of nanostructures will probably involve bilayer membrane vesicles as either the nanostructures themselves, or as templates or building blocks for more complex structures. Whether the vesicles are composed of surfactants, lipids or polymers, their stability in various environments must be optimized to suit the particular task at hand. Stabilizing the vesicles by polymerizing the surfactants themselves, or monomers templated within the vesicle or bilayer, has had a new surge of interest. Plating the vesicles, either by colloids or by polyelectrolytes, or templating the growth of various inorganic phases, has also shown promise, both in stabilizing the vesicle structure and in creating novel structures.     

Creation of nanostructures with poly(methyl methacrylate)-mediated nanotransfer printing

We demonstrate here a PMMA-mediated nanotransfer printing technique for reliably transferring nanoscale building blocks and sequentially building purpose-directed nanostructures. The utilization of PMMA film as a mediator introduced several features to this transfer approach, such as high efficiency, fidelity, universality, controllability, and multilevel transferability. Various nanostructures, such as an SWNTs-on-SAM structure, high-density crossbar array of SWNTs, a hybrid n-ZnO nanowire/p-SWNT cross-junction, a gold nanostructure-SAM-gold sandwich structure, a zigzag array of SWNTs, and gold nanobowl array were generated with this transfer approach. A metallic-semiconducting SWNT cross circuit was built to demonstrate its potential application in fabricating nanoelectronic devices. This technique paves the way to generate various structures with homo- or heterogeneous nanoscale building blocks, which facilitates exploring their fundamental properties and building novel devices.     

Peptide Nanomaterials Designed from Natural Supramolecular Systems

Natural supramolecular assemblies exhibit unique structural and functional properties that have been optimized over the course of evolution. Inspired by these natural systems, various bio‐nanomaterials have been developed using peptides, proteins, and nucleic acids as components. Peptides are attractive building blocks because they enable the important domains of natural protein assemblies to be isolated and optimized while retaining the original structures and functions. Furthermore, the peptide subunits can be conjugated with exogenous molecules such as peptides, proteins, nucleic acids, and metal nanoparticles to generate advanced functions. In this personal account, we summarize recent progress in the construction of peptide‐based nanomaterial designed from natural supramolecular systems, including (1) artificial viral capsids, (2) self‐assembled nanofibers, and (3) protein‐binding motifs. The peptides inspired by nature should provide new design principles for bio‐nanomaterials.     

Photoluminescence of Diphenylalanine Peptide Nano/Microstructures: From Mechanisms to Applications

Diphenylalanine (Phe‐Phe, FF) molecules, which can self‐assemble into highly ordered nano/microstructures, have increasingly aroused intense interests due to their special optical properties. In this review, recent advances in photoluminescence (PL) of supramolecular architectures of FF‐based peptide and the underlying mechanisms are highlighted. Mainly deep ultraviolet emission at around 285 nm and/or blue emission at ≈450 nm are observed in various FF peptide structures and its derivatives, which are primarily interpreted by quantum confinement effects, shallow radiative traps, and electron delocalization via hydrogen bonds in β‐ sheet structures. Furthermore, current applications of such fluorescent peptide nano/microstructures are also reviewed here, e.g., probing the number of water molecules confined in FF, temperature sensing, and visualization of deep ultraviolet beam. Yet, the PL mechanism is still under fierce debate and the application based on fluorescence is constantly under exploration. Thus, this review is endeavored to boost future explorations on the PL of the bioinspired FF peptide nano/microstructures.     

Self-assembly of inorganic nanoparticle vesicles and tubules driven by tethered linear block copolymers

Controllable self-assembly of nanoscale building blocks into larger specific structures provides an effective route for the fabrication of new materials with unique optical, electronic, and magnetic properties. The ability of nanoparticles (NPs) to self-assemble like molecules is opening new research frontiers in nanoscience and nanotechnology. We present a new class of amphiphilic "colloidal molecules" (ACMs) composed of inorganic NPs tethered with amphiphilic linear block copolymers (BCPs). Driven by the conformational changes of tethered BCP chains, such ACMs can self-assemble into well-defined vesicular and tubular nanostructures comprising a monolayer shell of hexagonally packed NPs in selective solvents. The morphologies and geometries of these assemblies can be controlled by the size of NPs and molecular weight of BCPs. Our approach also allows us to control the interparticle distance, thus fine-tuning the plasmonic properties of the assemblies of metal NPs. This strategy provides a general means to design new building blocks for assembling novel functional materials and devices.     

Self-assembled peptide nanostructures: the design of molecular building blocks and their technological utilization

In this tutorial review the process and applications of peptide self-assembly into nanotubes, nanospheres, nanofibrils, nanotapes, and other ordered structures at the nano-scale are discussed. The formation of well-ordered nanostructures by a process of self-association represents the essence of modern nanotechnology. Such self-assembled structures can be formed by a variety of building blocks, both organic and inorganic. Of the organic building blocks, peptides are among the most useful ones. Peptides possess the biocompatibility and chemical diversity that are found in proteins, yet they are much more stable and robust and can be readily synthesized on a large scale. Short peptides can spontaneously associate to form nanotubes, nanospheres, nanofibrils, nanotapes, and other ordered structures at the nano-scale. Peptides can also form macroscopic assemblies such as hydrogels with nano-scale order. The application of peptide building blocks in biosensors, tissue engineering, and the development of antibacterial agents has already been demonstrated.     

Deciphering the nanometer-scale organization and assembly of Lactobacillus rhamnosus GG pili using atomic force microscopy

In living cells, sophisticated functional interfaces are generated through the self-assembly of bioactive building blocks. Prominent examples of such biofunctional surfaces are bacterial nanostructures referred to as pili. Although these proteinaceous filaments exhibit remarkable structure and functions, their potential to design bioinspired self-assembled systems has been overlooked. Here, we used atomic force microscopy (AFM) to explore the supramolecular organization and self-assembly of pili from the Gram-positive probiotic bacterium Lactobacillus rhamnosus GG (LGG). High-resolution AFM imaging of cell preparations adsorbed on mica revealed pili not only all around the cells, but also in the form of remarkable star-like structures assembled on the mica surface. Next, we showed that two-step centrifugation is a simple procedure to separate large amounts of pili, even though through their synthesis they are covalently anchored to the cell wall. We also found that the centrifuged pili assemble as long bundles. We suggest that these bundles originate from a complex interplay of mechanical effects (centrifugal force) and biomolecular interactions involving the SpaC cell adhesion pilin subunit (lectin-glycan bonds, hydrophobic bonds). Supporting this view, we found that pili isolated from an LGG mutant lacking hydrophilic exopolysaccharides show an increased tendency to form tight bundles. These experiments demonstrate that AFM is a powerful platform for visualizing individual pili on bacterial surfaces and for unravelling their two-dimensional assembly on solid surfaces. Our data suggest that bacterial pili may provide a generic approach in nanobiotechnology for elaborating functional supramolecular interfaces assembled from bioactive building blocks.     

Low Dimension Semiconducting Composite Nanomaterials

Recently, low dimension nanostructures have gained considerable attention due to their technological potential as unique types of nanoscale building blocks for future optoelectronic devices and systems. Semiconducting composite nanomaterials, which can combine the advantages of two or more components, have been the focus in the area of nanomaterials synthesis and device application.In this paper, we report our work on the preparation of composite nanomaterials based on CNTs.CNTs were coated by organic or inorganic species via novel and facile methods (Fig. 1 and Fig.2).These functional CNTs based composites show eminent prospects and opportunities for new applications in a wide variation of areas.     

分级纳米材料的结构、制备及其应用

纳米材料因其独特的表面效应、体积效应和量子效应等特点,在化工、生物工程、医学和能源等领域有着广阔的应用。 由简单的低维纳米结构作为主要的构建单元并按照特定的排列方式组装成规整有序的三维结构,即分级纳米结构,已经开展了许多的研究。 本文综述了分级纳米结构的制备方法和微观结构,及其在污水处理、超级电容器、太阳能电池以及光催化等领域的应用。     

[60]富勒烯的超分子自组装研究进展

超分子自组装是发展超分子电子学的重要途径。随着纳米科学和技术的迅速发展,自组装技术已成功地应用于纳米尺度物质的维数、形貌和功能等的调控。作为构筑分子水平上一维、二维、三维有序功能结构和高有序分子聚集态结构的关键技术,超分子自组装技术有力地推动了具有优良光、电、磁性能的分子材料和纳米功能材料更深层次的研究。本文综述了超分子自组装在富勒烯科学领域的基础研究和应用,特别是对有利于自组织和自组装功能的富勒烯基衍生物的设计与合成、超分子作用力引导的具有特定结构的分子体系的可控自组装、以及富勒烯分子聚集态结构材料的光物理过程、超分子中电子转移和能量转移现象进行了描述;并对卟啉、四硫富瓦烯、碗烯和杯芳烃等一系列富π电子化合物和大环主体分子等包含[60]富勒烯的主体化合物的超分子作用和超分自组装体以及通过氢键、π-π作用、静电力和范德华力和金属配位作用形成的[60]富勒烯超分子自组装体进行了总结,对未来发展进行了展望。