Organic Self-assembly Research Articles

Accelerated Screening of Alternative DNA Base-Organic Molecule-Base Architectures via Integrated Theory and Experiment.

Organic molecule-mediated noncanonical DNA self-assembly expands the standard DNA base-pairing alphabets. However, only a very limited number of small molecules have been recognized as mediators because of the tedious and complicated experiments like crystallization and microscopy imaging. Here we present an integrative screening protocol incorporating molecular dynamics (MD) for fast theoretical simulation and native polyacrylamide gel electrophoresis for convenient experimental validation. Melamine, the molecule that was confirmed mediating noncanonical DNA base-pairing, and 38 other candidate molecules were applied to demonstrate the feasibility of this protocol. We successfully identified seven stable noncanonical DNA duplex structures, and another eight novel structures with sub-stability. In addition, we discovered that hairpins at both ends can significantly stabilize the noncanonical DNA structures, providing a guideline to design small organic molecule-incorporated DNA structures. Such an efficient screening protocol will accelerate the design of alternative DNA-molecule architectures beyond Watson-Crick pairs. Considering the wide range of potential mediators, it will also facilitate applications such as noncovalent, highly dense loading of drug molecules in DNA-based delivery system and probe design for sensitive detection of certain molecules.

Engineering Methacrylic Block Copolymers by Organic Catalysis Group Transfer Polymerization-Induced Self-Assembly in Nonpolar Media at Room Temperature

Engineering Methacrylic Block Copolymers by Organic Catalysis Group Transfer Polymerization-Induced Self-Assembly in Nonpolar Media at Room Temperature

Synthesis, Renal Clearance, and Photothermal Therapy Based on the Self-Assembly of a Nanomedicine Consisting of Quaterrylene Bisimide and Glycocluster Conjugates.

Renal-clearable nanomedicines are considered the next generation of nanomedicines, and show potential application for future clinical translations. However, it is important to determine whether self-assembly can form large aggregates that accrue in tumors and then tailor the size of these assemblies to be excreted renally. In this paper, a renal-clearable nanomedicine based on quanterrylene bisimide-mannose conjugates (QDI-Man) was developed. QDI-Man showed a high renal clearance efficiency of 80.31 ± 2.85% in mice. We confirmed that the self-assembly of QDI-Man exhibited a dynamic adjustment process through the renal filtration thresholds, that is, "aggregation → self-regulating the aggregate size through the renal filtration thresholds → reaggregating into aggregates". Benefiting from the modification of mannose-based glycoclusters, QDI-Man showed selective photothermal therapy because of the mannose receptors overexpressed in breast cancer cells, and showed good photothermal therapy in mice. This paper developed a dynamic adjustment theory for effective renal clearance based on organic self-assembly.

Hybrid dual-template induced nitrogen-doped hierarchically porous carbon as highly efficient oxygen reduction electrocatalyst

Fuel cell, as a promising future energy device, is one of the potential electric generators maintaining the sustainable development of our society and alleviating the major problems related to the energy shortage and environment pollution. However, the high cost and the limited resource of Pt remain the key obstacles for the commercialization of fuel cells. A hybrid dual-template strategy is developed to synthesize the nitrogen-doped ordered hierarchically porous carbon (NHMC) via a surfactant-templating organic resol self-assembly with F127 as soft template and SiO2 nanosphere as the hard-template. The NHMC catalyst presents three-dimensional hierarchically porous structure, composed of small ordered mesopore (∼3.8 nm), large 3-D interconnected mesopore (∼12 nm) as well as micropore. The catalyst exhibits tailored pore structures and a well-tuned surface chemical environment. It displays high onset potential of 0.91 V and half-wave potential of 0.76 V as well as high limiting current via four-electron pathway for oxygen reduction reaction (ORR). The NHMC also shows high stability and excellent methanol tolerance. This work brings inspiration for the synthesis of low-cos Pt-free catalyst with high activity, stability as well as high methanol tolerance.

Interfacial properties and aggregates of novel redox-active surfactant to synthesize silver nanoparticles at the air/water interface

An anionic and amphiphilic molecule, AQua (AQ-NH-(CH2)10COOH; where AQ is anthraquinone), which has two stimuli responsive functional-groups, can form self-assembled interfacial aggregates at the air-water interface and, their morphologies can be controlled by changing the subphase conditions such as the pH of the subphase. These interfacial morphologies may be altered from planar structures to wormlike aggregates which is a very rare observation in the literature. Moreover, the unique functional groups of AQua give possibility to reduce metal cations and allow the formation of organic/inorganic nanocomposite structures at the interface. In this context, formation of silver nanoparticles (AgNPs) via AQua-based self-assembled structures at the interface was studied using Langmuir techniques. The kinetics of the reduction process as well as the effect of various parameters were systematically examined. This study demonstrates that interfacial configuration of the AQua molecule at the interface as well as its orientation has a vital role in the morphology of either organic or inorganic self-assemblies formed. The morphology may be adjusted and designed interfacial structures may be obtained. The interfacial properties of AQua, a novel material, may be used in a wide variety of fields such as biotechnology, medicine, energy and pharmaceuticals.

Strategies for Pore-Diameter Control in Mesoporous Carbons Derived from Organic Self-Assembly Processes

Soft-templating techniques have greatly facilitated access to (ordered) mesoporous carbon materials. A key strength of these approaches is that the resulting material can be shaped by a multitude of parameters – rendering soft-templating inherently versatile regarding features such as pore arrangement or pore sizes. Nonetheless, rational manipulation of pore sizes/diameters, let alone a systematic variation thereof, remains a formidable challenge with high relevance for research fields as diverse as catalysis, sensing or energy storage and conversion. Thus, this Short Review aims to provide a structured account of the most frequently employed strategies to impact mesopore diameters in carbon materials derived via soft-templating.1. Introduction2. Carbonization Temperature3. Stoichiometry4. Swelling Agents5. Design of Polymeric SDAs/Templates6. Conclusions and Outlook

Mesoporous Carbon Fibers with Tunable Mesoporosity for Electrode Materials in Energy Devices.

To improve the properties of mesoporous carbon (MC), used as a catalyst support within electrodes, MC fibers (MCFs) were successfully synthesized by combining organic–organic self-assembly and electrospinning deposition and optimizing heat treatment conditions. The pore structure was controlled by varying the experimental conditions. Among MCFs, MCF-A, which was made in the most acidic condition, resulted in the largest pore diameter (4–5 nm), and the porous structure and carbonization degree were further optimized by adjusting heat treatment conditions. Then, since the fiber structure is expected to have an advantage when MCFs are applied to devices, MCF-A layers were prepared by spray printing. For the resistance to compression, MCF-A layers showed higher resistance (5.5% change in thickness) than the bulk MC layer (12.8% change in thickness). The through-plane resistance was lower when the fiber structure remained more within the thin layer, for example, +8 mΩ for 450 rpm milled MCF-A and +12 mΩ for 800 rpm milled MCF-A against the gas diffusion layer (GDL) 25BC carbon paper without a carbon layer coating. The additional advantages of MCF-A compared with bulk MC demonstrate that MCF-A has the potential to be used as a catalyst support within electrodes in energy devices.

In situ formation of tetraphenylethylene nano-structures on microgels inside living cells via reduction-responsive self-assembly.

Controlling the assembly of synthetic molecules in living systems is of significance for their adaptive applications. However, it is difficult to achieve, especially for composite self-assemblies, due to the complexity and dynamic change of the intracellular environment, and there exist technical difficulties for the direct visualization of organic and polymer self-assemblies. Herein, we demonstrate a novel strategy for the in situ formation of self-assembled micro-nano composite structures in a cell milieu using reduction-responsive microgels (MGs) as a platform. The MGs were prepared by a templating and crosslinking method using a synthetic amphiphlic polymer as the basic material and porous CaCO3 microparticles as the template. The aggregation-induced emission (AIE) tetraphenylethylene moieties and reduction-labile disulfide bonds in the MGs were employed as the self-assembly building blocks and triggering sites for the intracellular self-assembly, respectively. In the presence of reductive agents such as glutathione, nano-spikes were gradually formed on the MGs. After the MGs were internalized by cells, the in situ formation of microgel/nano-spike composite structures was evidenced by the enhanced fluorescence intensity and was further confirmed by direct transmission electron microscopy observation. This work provides an effective strategy to cope with the challenging task of achieving and probing controlled self-assembly in a cell milieu, leading to new insights into investigating biological self-assembly and promoting the development of micro-/nanomaterials by learning from nature.

Metallohelices emulate the properties of short cationic α-helical peptides.

Naturally occurring peptides in many living systems perform antimicrobial and anticancer host defence roles, but their potential for clinical application is limited by low metabolic stability and relatively high costs of goods. Self-assembled helical metal complexes provide an attractive synthetic platform for non-peptidic architectures that can emulate some of the properties of short cationic α-helical peptides, with tuneable charge, shape, size and amphipathicity. Correspondingly there is a growing body of evidence demonstrating that these supramolecular architectures exhibit bioactivity that emulates that of the natural systems. We review that evidence in the context of synthetic advances in the area, driven by the potential for biomedical applications. We note some design considerations for new biologically-relevant metallohelices, and give our outlook on the future of these compounds as therapeutic peptidomimetics.

An electrostatically regulated organic self-assembly for rapid and sensitive detection of heparin in serum.

Heparin (Hep) is a highly negatively charged linear glycosaminoglycan involved in various physiological processes, especially blood coagulation. Hep is also a first-line drug for anticoagulation and prevention of thromboembolism, but its overdose will cause serious side effects. Herein, we designed a long-wavelength double-charged cationic fluorescent probe PYPN, and studied its aggregation state and detection performance for Hep. PYPN was readily synthesized through a one-step reaction without complicated purification. In aqueous medium, PYPN molecules with an amphiphilic structure spontaneously form nano-assemblies, which can be immediately decomposed by Hep due to the formation of a PYPN-Hep complex based on electrostatic attraction. The assembly shows a fast, sensitive and ratiometric fluorescence response to Hep, without being obviously interfered by other compounds. In various serum matrices, the fluorescence intensity ratio F610/F470 has a good linearity with Hep concentration (0-12 μg mL-1), and the detection limit (0.11-0.12 U mL-1) is lower than the minimum concentration (0.2 U mL-1) used in clinical treatment. Our study provides an easy-to-prepare and feasible tool for the selective and sensitive quantification of Hep in serum.

Molecular packing handedness dominated by the chirality of the lactic acid residue near the liquid crystalline core

ABSTRACT Eight dichiral compounds containing two lactic acid residues and one perfluorocarbon chain are synthesised. Six of them are liquid crystals with an enantiotropic SmA phase. Two of them are liquid crystals with enantiotropic SmA and SmC* phases. Although (R,R)-3 and (R,R)-4 molecules pack in monolayer structures at the crystalline states, (S,R)-3 and (R,S)-4 molecules pack in bilayer structures at the crystalline states. The optical activity of these compounds is mainly controlled by the chirality of the lactic acid residue near the liquid crystalline core. The dichiral compounds can self-assemble into nanotubes or twisted nanoribbons in methanol. Circular dichroism characterisation indicated that the stacking handedness of the liquid crystalline cores in the organic self-assemblies was also dominated by the chirality of the lactic acid residue near the liquid crystalline core.

Hybrid Hydrogel Electrolyte Based on Metal-Organic Supermolecular Self-Assembly and Polymer Chemical Cross-Linking for Rechargeable Aqueous Zn-MnO2 Batteries.

Multifunctional metal-organic supramolecular hydrogels have achieved great progress nowadays. However, their applications in aqueous batteries for flexible energy storage devices remain limited due to their unsatisfactory mechanical properties. Here, we report a rapid formation of supramolecular hydrogel by adenosine 5'-monophosphate (AMP) and manganese ions (Mn2+). Additionally, the AMP-Mn hydrogel is combined with chemical cross-linking poly(vinyl alcohol) (PVA) polymer networks to form an AMP-Mn/PVA hybrid hydrogel, which effectively solves the problems with regard to the mechanical properties and stability of metal-organic supramolecular hydrogels as well as self-healing of tough chemical cross-linking polymer networks. The AMP-Mn/PVA hybrid hydrogel served as the hydrogel electrolyte to fabricate flexible Zn-MnO2 batteries, which exhibit fast ion conductivity, excellent electrochemical stability, and robust mechanical strength, indicating feasible practical application prospects. This investigation provides a promising opportunity for the application of metal-organic supramolecular hydrogels in the field of energy storage.

Nanoarchitectonics from Atom to Life.

Functional materials with rational organization cannot be directly created only by nanotechnology-related top-down approaches. For this purpose, a novel research paradigm next to nanotechnology has to be established to create functional materials on the basis of deep nanotechnology knowledge. This task can be assigned to an emerging concept, nanoarchitectonics. In the nanoarchitectonics approaches, functional materials were architected through combination of atom/molecular manipulation, organic chemical synthesis, self-assembly and related spontaneous processes, field-applied assembly, micro/nano fabrications, and bio-related processes. In this short review article, nanoarchitectonics-related approaches on materials fabrications and functions are exemplified from atom-scale to living creature level. Based on their features, unsolved problems for future developments of the nanoarchitectonics concept are finally discussed.

Helicity of perfluoroalkyl chains controlled by the self-assembly of the Ala-Ala dipeptides.

Four Ala-Ala dipeptides with a perfluoroalkyl chain at the N-terminal were synthesized. They were able to self-assemble into helical nanofibers and/or twisted nanobelts in a mixture of DMSO/H2 O. The handedness of nanofibers and nanobelts was controlled by the chirality of the alanine at the N-terminal. The stacking handedness of the phenylene groups and the helicity of the perfluoroalkyl chain were studied using circular dichroism spectroscopy and vibrational circular dichroism, respectively. The chirality of the alanine at N-terminal controlled the stacking handedness of the neighboring phenylene groups. Moreover, due to the low potential barrier between M- and P-helices of the perfluorocarbon chain, the handedness of the organic self-assemblies eventually controlled the helicity of the perfluorocarbon chain. X-ray diffraction indicated that a lamellar structure was formed by the dimers of the dipeptides.

Design of Engineered Cyclodextrin Derivatives for Spontaneous Coating of Highly Porous Metal-Organic Framework Nanoparticles in Aqueous Media.

Nanosized metal-organic frameworks (nanoMOFs) MIL-100(Fe) are highly porous and biodegradable materials that have emerged as promising drug nanocarriers. A challenging issue concerns their surface functionalization in order to evade the immune system and to provide molecular recognition ability, so that they can be used for specific targeting. A convenient method for their coating with tetraethylene glycol, polyethylene glycol, and mannose residues is reported herein. The method consists of the organic solvent-free self-assembly on the nanoMOFs of building blocks based on β-cyclodextrin facially derivatized with the referred functional moieties, and multiple phosphate groups to anchor to the nanoparticles’ surface. The coating of nanoMOFs with cyclodextrin phosphate without further functional groups led to a significant decrease of macrophage uptake, slightly improved by polyethylene glycol or mannose-containing cyclodextrin phosphate coating. More notably, nanoMOFs modified with tetraethylene glycol-containing cyclodextrin phosphate displayed the most efficient “stealth” effect. Mannose-coated nanoMOFs displayed a remarkably enhanced binding affinity towards a specific mannose receptor, such as Concanavalin A, due to the multivalent display of the monosaccharide, as well as reduced macrophage internalization. Coating with tetraethylente glycol of nanoMOFs after loading with doxorubicin is also described. Therefore, phosphorylated cyclodextrins offer a versatile platform to coat nanoMOFs in an organic solvent-free, one step manner, providing them with new biorecognition and/or “stealth” properties.

Large, Mesoporous Carbon Nanoparticles with Tunable Architectures for Energy Storage

We report the synthesis of giant carbon particles with spherical and interconnected porous morphologies. Direct organic–organic self-assembly between phenolic resin and polystyrene-block-poly(ethylene oxide) (PS-b-PEO) was employed to prepare these highly ordered carbon particles. Mesoporous carbon nanoparticles with tunable textural characteristics such as large surface area, uniform pore structure, and high thermal properties were achieved by simply adjusting the ratio between the block copolymer to phenol without using acid, base, or activating agents. The synthesized nanoparticles possess a very high surface area of up to 832 m2 g–1, and ultrasmall pore size, as small as 3 nm, and exhibited excellent electrochemical performance when used as active electrodes for lithium-ion batteries. Making use of the secondary interactions between the functional groups of the block copolymer and phenol, this study created tunable nanoparticles with excellent surface area and uniform morphologies that can be used in ...

A “center-determination” phenomenon of C13H27CO-Gly-Ala-Ala lipotripetides: relationship between the molecular chirality and handedness of organic self-assemblies

The chirality of the central alanine residue dominates the handedness of molecular packing and that of organic self-assemblies.

Facile synthesis of nitrogen-doped graphene aerogels for electrochemical detection of dopamine

Nitrogen-doped graphene aerogels with three-dimensional network structures are fabricated using hydrothermal method which includes the reduction of graphene oxide by organic amine and self-assembly of reduced graphene oxide. The effect of amine-containing compounds including aniline, 2-aminoethanol, ethylenediamine, melamine and chitosan on the assembly of nitrogen-doped graphene aerogel is investigated. The microstructure and chemical composition of nitrogen-doped graphene aerogels are characterized. The results reveal that nitrogen-doped graphene aerogel prepared using aniline as nitrogen source possesses a large specific surface area, high nitrogen content, good mechanical strength and excellent electrical conductivity. Based on these features, the as-prepared nitrogen-doped graphene aerogel shows high performance in electrochemical detection of dopamine in the presence of uric acid and ascorbic acid. Given the facile and scalable processability of aerogels, the proposed nitrogen-doped graphene aerogels are expected to have potential applications in sensors and other related devices.

Aqueous Assembly of Oxide and Fluoride Nanoparticles into 3D Microassemblies.

We demonstrate rapid [∼mm3/(h·L)] organic ligand-free self-assembly of three-dimensional, >50 μm single-domain microassemblies containing up to 107 individual aligned nanoparticles through a scalable aqueous process. Organization and alignment of aqueous solution-dispersed nanoparticles are induced by decreasing their pH-dependent surface charge without organic ligands, which could be temperature-sensitive or infrared light absorbing. This process is exhibited by transforming both dispersed iron oxide hydroxide nanorods and lithium yttrium fluoride nanoparticles into high packing density microassemblies. The approach is generalizable to nanomaterials with pH-dependent surface charge (e.g., oxides, fluorides, and sulfides) for applications requiring long-range alignment of nanostructures as well as high packing density.

Chiral carbonaceous nanotubes prepared by carbonization of chiral organic self-assemblies

Single-handed helical tantalum pentoxide nanotubes with inner chiral organic self-assemblies were prepared through a supramolecular templating approach. After carbonization and removal of tantalum pentoxide, single-handed twisted carbonaceous nanotubes were obtained. The handedness of the carbonaceous nanotubes followed that of the tantalum pentoxide nanotubes. The carbonaceous nanotubes were formed due to the adsorption of the organic self-assemblies on the inner surfaces of the tantalum pentoxide nanotubes and the shrinkage of organic self-assemblies during the drying process and subsequently carbonization. The X-ray diffraction and Raman spectroscopy characterizations indicated that the carbon was amorphous. The circular dichroism spectra indicated that the twisted carbonaceous nanotubes exhibited optical activity. The elemental analysis showed that these carbonaceous nanotubes were N-doped. These N-doped carbonaceous materials might find applications as catalysts and chirality sensors.