Growth and Origami Folding of DNA on Nanoparticles for High‐Efficiency Molecular Transport in Cellular Imaging and Drug Delivery

A novel three‐dimensional (3D) superstructure based on the growth and origami folding of DNA on gold nanoparticles (AuNPs) was developed. The 3D superstructure contains a nanoparticle core and dozens of two‐dimensional DNA belts folded from long single‐stranded DNAs grown in situ on the nanoparticle by rolling circle amplification (RCA). We designed two mechanisms to achieve the loading of molecules onto the 3D superstructures. In one mechanism, ligands bound to target molecules are merged into the growing DNA during the RCA process (merging mechanism). In the other mechanism, target molecules are intercalated into the double‐stranded DNAs produced by origami folding (intercalating mechanism). We demonstrated that the as‐fabricated 3D superstructures have a high molecule‐loading capacity and that they enable the high‐efficiency transport of signal reporters and drugs for cellular imaging and drug delivery, respectively.     

Ring Shuttling Controls Macroscopic Motion in a Three‐Dimensional Printed Polyrotaxane Monolith

Amplification of molecular motions into the macroscopic world has great potential in the development of smart materials. Demonstrated here is an approach that integrates mechanically interlocked molecules into complex three‐dimensional (3D) architectures by direct‐write 3D printing. The design and synthesis of polypseudorotaxane hydrogels, which are composed of α‐cyclodextrins and poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO‐PPO‐PEO) triblock copolymers, and their subsequent fabrication into polyrotaxane‐based lattice cubes by 3D printing followed by post‐printing polymerization are reported. By switching the motion of the α‐cyclodextrin rings between random shuttling and stationary states through solvent exchange, the polyrotaxane monolith not only exhibits macroscopic shape‐memory properties but is also capable of converting the chemical energy input into mechanical work by lifting objects against gravity.     

Self‐Assembled Functional DNA Superstructures as High‐Density and Versatile Recognition Elements for Printed Paper Sensors

Micrometer‐sized functional nucleic acid (FNA) superstructures (denoted as 3D DNA) were examined as a unique class of biorecognition elements to produce highly functional bioactive paper surfaces. 3D DNA containing repeating sequences of either a DNA aptamer or DNAzyme was created from long‐chain products of rolling circle amplification followed by salt aging. The resulting 3D DNA retained its original spherical shape upon inkjet printing and adhered strongly to the paper surface via physisorption. 3D DNA paper sensors showed resistance to degradation by nucleases, suppressed nonspecific protein adsorption, and provided a much higher surface density of functional DNA relative to monomeric FNAs, making such species ideally suited for development of paper‐based biosensors.     

聚合物基微纳米功能复合材料3D打印加工的研究

高分子材料3D打印加工可制备传统加工不能制备的形状复杂的高分子制件,是近年来发展很快的先进制造技术。但适用于3D打印加工的高分子材料种类少,结构功能单一,难以制备高分子功能器件。本文介绍了我们在聚合物基微纳米功能复合材料3D打印加工方面的研究工作:通过有机/无机杂化、固相剪切碾磨、超声辐照、分子复合等技术制备适合于选择性激光烧结(SLS)和熔融沉积成型(FDM)的聚合物基微纳米功能复合材料;实现了聚合物基微纳米功能复合粉体的SLS加工和功能复合丝条的FDM加工;研究了3D打印低维构建、层层叠加、自由界面成型、复杂固-液-固转变过程;建立了功能复合粉体球形化技术,发明了直接熔融挤出新型FDM打印机;制备了常规加工方法不能制备的数种形状复杂的功能器件,如尼龙11/钛酸钡压电器件、柔性聚氨酯/碳纳米管传感器、个性化人颌骨模型等,突破了传统加工难以制备复杂形状制品和目前3D打印难以制备功能制品的局限。     

Recrystallization‐Induced Self‐Assembly for the Growth of Cu2O Superstructures

The assembly of inorganic nanoparticles (NPs) into 3D superstructures with defined morphologies is of particular interest. A novel strategy that is based on recrystallization‐induced self‐assembly (RISA) for the construction of 3D Cu₂O superstructures and employs Cu₂O mesoporous spheres with diameters of approximately 300 nm as the building blocks has now been developed. Balancing the hydrolysis and recrystallization rates of the CuCl precursors through precisely adjusting the experimental parameters was key to success. Furthermore, the geometry of the superstructures can be tuned to obtain either cubes or tetrahedra and was shown to be dependent on the growth behavior of bulk CuCl. The overall strategy extends the applicability of recrystallization‐based processes for the guided construction of assemblies and offers unique insights for assembling larger particles into complicated 3D superstructures.     

Two‐Dimensional Mesoscale‐Ordered Conducting Polymers

Despite the availability of numerous two‐dimensional (2D) materials with structural ordering at the atomic or molecular level, direct construction of mesoscale‐ordered superstructures within a 2D monolayer remains an enormous challenge. Here, we report the synergic manipulation of two types of assemblies in different dimensions to achieve 2D conducting polymer nanosheets with structural ordering at the mesoscale. The supramolecular assemblies of amphipathic perfluorinated carboxylic acids and block co‐polymers serve as 2D interfaces and meso‐inducing moieties, respectively, which guide the polymerization of aniline into 2D, free‐standing mesoporous conducting polymer nanosheets. Grazing‐incidence small‐angle X‐ray scattering combined with various microscopy demonstrates that the resulting mesoscale‐ordered nanosheets have hexagonal lattice with d‐spacing of about 30 nm, customizable pore sizes of 7–18 nm and thicknesses of 13–45 nm, and high surface area. Such template‐directed assembly produces polyaniline nanosheets with enhanced π–π stacking interactions, thereby resulting in anisotropic and record‐high electrical conductivity of approximately 41 S cm^?1 for the pristine polyaniline nanosheet based film and approximately 188 S cm^?1 for the hydrochloric acid‐doped counterpart. Our moldable approach creates a new family of mesoscale‐ordered structures as well as opens avenues to the programmed assembly of multifunctional materials.     

3D Printing of Silk Protein Structures by Aqueous Solvent‐Directed Molecular Assembly

Hierarchical molecular assembly is a fundamental strategy for manufacturing protein structures in nature. However, to translate this natural strategy into advanced digital manufacturing like three‐dimensional (3D) printing remains a technical challenge. This work presents a 3D printing technique with silk fibroin to address this challenge, by rationally designing an aqueous salt bath capable of directing the hierarchical assembly of the protein molecules. This technique, conducted under aqueous and ambient conditions, results in 3D proteinaceous architectures characterized by intrinsic biocompatibility/biodegradability and robust mechanical features. The versatility of this method is shown in a diversity of 3D shapes and a range of functional components integrated into the 3D prints. The manufacturing capability is exemplified by the single‐step construction of perfusable microfluidic chips which eliminates the use of supporting or sacrificial materials. The 3D shaping capability of the protein material can benefit a multitude of biomedical devices, from drug delivery to surgical implants to tissue scaffolds. This work also provides insights into the recapitulation of solvent‐directed hierarchical molecular assembly for artificial manufacturing.     

Ion-driven ATP pump by self-organized hybrid membrane materials

We report new hybrid organic-inorganic materials, based on macrocyclic receptors 1-3 self-organized in tubular superstructures prepared by sol-gel process. Fourier transform infrared (FTIR) and NMR spectroscopic analyses demonstrate that the self-organization by hydrogen bonding of organogel superstructures of 2 and 3 were preserved in the hybrid materials throughout the sol-gel process. The molecular arrangement of heteroditopic receptors defines a particularly attractive functional transport device for both cation (tubular macrocycles) and anion (sandwich-urea) directional-diffusion transport mechanism in the hybrid membrane material. This system has been employed successfully to design a solid dense membrane, functioning as an ion-powered adenosine triphosphate (ATP(2)(-)) pump, and illustrates how a self-organized hybrid material performs interesting and potentially useful functions.     

Synthesis and one‐dimensional assembly of cylindrical polymer nanoparticles prepared from tricomponent bottlebrush copolymers

Biological systems feature controlled assembly of well‐defined building blocks at different length scales. While major progress has been achieved in directing the assembly of synthetic molecular building blocks, controlled organization of nanostructured units into micro‐ and macroscale aggregates remains a challenge. Herein, we report the synthesis of well‐defined nanostructured building blocks, cylindrical polymeric nanoparticles with controlled dimensions and inner surface chemistry, and their dynamic anisotropic organization into one‐dimensional assemblies. Nanoparticle building blocks were produced by molecular templating of cylindrical bottlebrush copolymers featuring tricomponent side chains. The produced nanostructures were composed of a nonionic and bioinert polyethylene glycol (PEG) shell and stimuli‐responsive poly(methacrylic acid) (PMA) chains grafted on the interior. We show that pH‐dependent interactions between PMA chains exposed only at the nanoparticle ends lead to anisotropic end‐to‐end association of parent cylindrical nanostructures into elongated superstructures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3868–3874     

Columnar Mesophase Formation of Cyclohexa‐m‐phenylene‐Based Macrocycles

Two novel discotic macrocycles, substituted cyclohexa‐m‐phenylene (CHP) and cyclo‐3,6‐trisphenanthrylene (CTP), and the linear oligomer 3,3′:6′,3′′‐terphenanthrene (TP) as a model substance have been synthesized by repetitive cross‐coupling reactions. To correlate the molecular design with the supramolecular architecture and the established macroscopic order, 2D wide‐angle X‐ray scattering experiments were performed on mechanically extruded filaments. At room temperature in their crystalline phases, all three compounds revealed columnar assemblies in which the macrocycles self‐organized by π‐stacking interactions. The degree of macroscopic order was found to depend upon the planarity and stiffness of the aromatic core. The flexible CHP ring showed a poor macroscopic order of the columnar structures and a low isotropization temperature, whereas the more‐planar, less‐flexible CTP self‐assembled into well‐defined superstructures. The larger π‐stacking area and the more‐pronounced intermolecular interactions for CTP led to the formation of a mesophase over a very large temperature range. The surprising columnar organization of the “open” TP system was explained by back‐folding of the molecule into a ringlike structure.     

Remarkable effect of pre‐organization on the self assembly in chiral liquid crystals

In this article, liquid crystal phases possessing a helical molecular assembly, including frustrated three dimensional (3D) structures, are overviewed. Then, the chirality‐originated superstructures in liquid crystals studied by the author are reviewed. The importance of the concept of “pre‐organization” is highlighted, thus, molecular design producing a strong chiral effect has been proposed. Dichiral twin materials have been prepared systematically based on this concept, and correlation between molecular architectures and resulting frustrated liquid crustal phases, such as smectic blue, cubic, tetragonal smectic Q, and sponge phases, has been investigated. An electrically induced anisotropic birefringent structure in the chiral isotropic phase and a photoinduced 3D‐3D phase transition in the smectic Q phase are introduced as possible application on the basis of the frustrated chiral 3D structured liquid crystal phases. A new type of chiral effect inducing the structural anisotropy in the 3D cubic structure of soft material is also described. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 340–355; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200900029     

Three‐dimensional printing of poly(lactic acid) bio‐based composites with sugarcane bagasse fiber: Effect of printing orientation on tensile performance

The cellulose fiber was extracted from the abandoned crop sugarcane bagasse (SCB) by means of chemical treatment methods. Poly(lactic acid) (PLA) bio‐based composites with SCB were prepared through fused deposition modeling (FDM) 3D‐printing technology, and the morphologies, mechanical properties, crystallization properties, and thermal stability of 3D‐printed composites were investigated. Compared with the neat PLA, the incorporation of SCB into PLA reduces the tensile strength and flexural strength of 3D‐printed samples but increases the flexural modulus. The difference in tensile performance and bending performance is that the tensile strength of 3D‐printed samples is best when the SCB content is 6 wt%, while the flexural modulus continuously decreases as the SCB content increases. Furthermore, the effects of various printing methods on the tensile performance of 3D‐printed samples were explored via modifying G‐code of 3D models. The results indicate that the optimum SCB fiber content is identical for all printing methods except method “vertical.” Due to the fibers and molecular chains are oriented to varying degrees with altering raster angle in 3D‐printed samples, the fully oriented sample printed by method “parallel” has a better tensile strength. Besides, SCB exhibits enough high thermal decomposition temperature to meet requirements for melt extrusion processing of PLA composites, and SCB fiber is capable of promoting the crystallization of PLA.     

Multifaceted polymeric materials in three‐dimensional processing (3DP) technologies: Current progress and prospects

Three‐dimensional printing (3DP) technologies, which are sets of powerful deposition methods employed to fabricate 3D objects with materials in the fields of material sciences and engineering, biomedical and biocompatible structural components, automotive, aviation, and polymers, among others, are currently rapidly developing manufacturing technologies. The methods have significant advantages, which include designing flexibility, enhanced geometrical freedom, low cost, and net shape manufacture, among others, over the traditional “subtractive” method. This review highlights the major 3D printing techniques, especially in the fields of advanced polymeric material fabrication and engineering, as well as the synergy in the incorporation of different types of polymeric materials and composites in a process that will lead to an enhancement of dimensional accuracy for 3D technologies. Furthermore, composite ink systems especially polymer‐based and hydrogel‐based in tissue engineering applications are also discussed.     

Metal–Organic Frameworks: From Molecules/Metal Ions to Crystals to Superstructures

Metal–organic frameworks (MOFs) are among the most attractive porous materials known today, exhibiting very high surface areas, tuneable pore sizes and shapes, adjustable surface functionality, and flexible structures. Advances in the formation of MOF crystals, and in their subsequent assembly into more complex and/or composite superstructures, should expand the scope of these materials in many applications (e.g., drug delivery, chemical sensors, selective reactors and removal devices, etc.) and facilitate their integration onto surfaces and into devices. This Concept article aims to showcase recently developed synthetic strategies to control the one‐, two‐ and three‐dimensional (1‐, 2‐ and 3D) organisation of MOF crystals.     

A Versatile 3D and 4D Printing System through Photocontrolled RAFT Polymerization

Reversible addition‐fragmentation chain‐transfer (RAFT) polymerization is a valuable tool for synthesizing macromolecules with controlled topologies and diverse chemical functionalities. However, the application of RAFT polymerization to additive‐manufacturing processes has been prevented due to the slow polymerization rates of typical systems. In this work, we developed and optimized a rapid visible (green) light mediated RAFT polymerization process and applied it to an open‐air 3D printing system. The reaction components are non‐toxic, metal free and environmentally friendly, which tailors these systems toward biomaterial fabrication. The inclusion of RAFT agent in the photosensitive resin provided control over the mechanical properties of 3D printed materials and allowed these materials to be post‐functionalized after 3D printing. Additionally, photoinduced spatiotemporal control of the network structure provided a one‐pass approach to 4D printed materials. This RAFT‐mediated 3D and 4D printing process should provide access to a range of new functional and stimuli‐responsive materials.     

Peptide Conjugates for Directing the Morphology and Assembly of 1D Nanoparticle Superstructures

Designed peptide conjugates molecules are used to direct the synthesis and assembly of gold nanoparticles into complex 1D nanoparticle superstructures with various morphologies. Four peptide conjugates, each based on the gold‐binding peptide (AYSSGAPPMPPF; PEP_Au), are prepared: C₁₂H₂₃O‐AYSSGAPPMPP ( 1 ), C₁₂H₂₃O‐AYSSGAPPMPPF ( 2 ), C₁₂H₂₃O‐AYSSGAPPMPPFF ( 3 ), and C₁₂H₂₃O‐AYSSGAPPMPPFFF ( 4 ). The affect that C‐terminal hydrophobic F residues have on both the soft‐assembly of the peptide conjugates and the resulting assembly of gold nanoparticle superstructures is examined. It is shown that the addition of two C‐terminal F residues ( 3 ) leads to thick, branched 1D gold nanoparticle superstructures, whereas the addition of three C‐terminal F residues ( 4 ) leads to bundling of thin 1D nanoparticle superstructures.     

Phase Transformation Behavior of a Two‐Dimensional Zeolite

Understanding the molecular‐level mechanisms of phase transformation in solids is of fundamental interest for functional materials such as zeolites. Two‐dimensional (2D) zeolites, when used as shape‐selective catalysts, can offer improved access to the catalytically active sites and a shortened diffusion length in comparison with their 3D analogues. However, few materials are known to maintain both their intralayer microporosity and structure during calcination for organic structure‐directing agent (SDA) removal. Herein we report that PST‐9, a new 2D zeolite which has been synthesized via the multiple inorganic cation approach and fulfills the requirements for true layered zeolites, can be transformed into the small‐pore zeolite EU‐12 under its crystallization conditions through the single‐layer folding process, but not through the traditional dissolution/recrystallization route. We also show that zeolite crystal growth pathway can differ according to the type of organic SDAs employed.     

Morphology‐Dependent Electrochemical Properties of CuS Hierarchical Superstructures

Hierarchical superstructures formed by self‐assembled nanoparticles exhibit interesting electrochemical properties that can potentially be exploited in Li‐ion batteries (LIBs) as possible electrode materials. In this work, we tested two different morphologies of CuS superstructures for electrodes, namely, tubular dandelion‐like and ball‐like assemblies, both of which are composed of similar small covellite nanoparticles. These two CuS morphologies are characterized by their markedly different electrochemical performances, suggesting that their complex structures/morphologies influence the electrochemical properties. At 1.12 A g^?1, the cells made with CuS tubular structures delivered about 420 mAh g^?1, and at 0.56 A g^?1, the capacity was as high as about 500 mAh g^?1 with good capacity retention. Their ease of preparation and processing, together with good electrochemical performance, make CuS tubular dandelion‐like clusters attractive for developing low‐cost LIBs based on conversion reactions.