Left‐handed helical polymer resin nanotubes prepared by using N‐palmitoyl glucosamine

Although the preparation of single‐handed helical inorganic and hybrid organic‐inorganic nanotubes is well developed, approaches to the formation of single‐handed organopolymeric nanotubes are limited. Here, left‐handed helical m‐phenylenediamine‐formaldehyde resin and 3‐aminophenol‐formaldehyde resin nanotubes were prepared by using N‐palmitoyl glucosamine that can self‐assemble into left‐handed twisted nanoribbons in a mixture of methanol and water. In the reaction mixture, the helical pitch of the nanoribbons decreased with increasing reaction time. The resin nanotubes were obtained after removing the N‐palmitoyl glucosamine template, and circular dichroism spectroscopy indicated that the organopolymeric nanotubes had optical activity. Carbonaceous nanotubes were then prepared by carbonization of the 3‐aminophenol‐formaldehyde resin nanotubes.     

Inner Surface Chirality of Single‐Handed Twisted Carbonaceous Tubular Nanoribbons

Single‐handed twisted 4,4′‐biphenylene‐bridged polybissilsesquioxane tubular nanoribbons and single‐layered nanoribbons were prepared by tuning the water/ethanol volume ratio in the reaction mixture at pH = 11.6 through a supramolecular templating approach. The single‐layered nanoribbons were formed by shrinking tubular nanoribbons after the removal of the templates. In addition, solvent‐induced handedness inversion was achieved. The handedness of the polybissilsesquioxanes could be controlled by changing the ethanol/water volume ratio in the reaction mixture. After carbonization at 900 °C for 4.0 h and removal of silica, single‐handed twisted carbonaceous tubular nanoribbons and single‐layered nanoribbons with micropores in the walls were obtained. X‐ray diffraction and Raman spectroscopy analyses indicated that the carbon is predominantly amorphous. The circular dichroism spectra show that the twisted tubular nanoribbons exhibit optical activity, while the twisted single‐layered nanoribbons do not. The results shown here indicate that chirality is transferred from the organic self‐assemblies to the inner surfaces of the 4,4′‐biphenylene‐bridged polybissilsesquioxane tubular nanoribbons and subsequently to those of the carbonaceous tubular nanoribbons. Chirality 27:809–815, 2015. © 2015 Wiley Periodicals, Inc.     

Self‐assembling organo‐peptide bolaphiles with KLK tripeptide head groups display selective antibacterial activity

In keeping with recent efforts to generate compounds for antibiotic and microbicide development, we focused on the creation of non‐natural organo‐peptide hybrids of antimicrobial peptide amides (KLK(L)_nKLK‐NH₂) derived from sapecin B and a self‐assembling oligoglycine organo‐peptide bolaphile containing an ω‐amino fatty acid residue. The hybrid organo‐peptide bolaphiles with two cationic KLK tripeptide motifs linked with an ω‐amino acid residue (penta‐, octa‐ or undecamethylene chain) maintained the self‐assembling properties of the root oligoglycine bolaphile. Electron microscopy clearly revealed complex supramolecular architectures for both sapecin B‐derived peptides and the hybrid analogues. FT‐IR spectroscopy indicated that the supramolecular structures were composed primarily of β‐sheets. CD revealed that the hybrid bolaphiles did not share the same secondary structures as the sapecin B peptides in solution. However, although secondary structures of antimicrobial peptides are central in the activity, the organo‐peptide bolaphiles also retained the potent antimicrobial activity of the leader sapecin B‐derived peptide against both Gram‐positive and Gram‐negative bacteria. In general, the hybrids were more selective than the sapecin B peptides, as they displayed little or no appreciable haemolytic activity. The results obtained herald a new approach for the design of purpose‐built hybrid organo‐peptide bolaphiles. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Self‐assembling amyloid‐like peptides as exogenous second harmonic probes for bioimaging applications

Amyloid‐like peptides are an ideal model for the mechanistic study of amyloidosis, which may lead to many human diseases, such as Alzheimer disease. This study reports a strong second harmonic generation (SHG) effect of amyloid‐like peptides, having a signal equivalent to or even higher than those of endogenous collagen fibers. Several amyloid‐like peptides (both synthetic and natural) were examined under SHG microscopy and shown they are SHG‐active. These peptides can also be observed inside cells (in vitro). This interesting property can make these amyloid‐like peptides second harmonic probes for bioimaging applications. Furthermore, SHG microscopy can provide a simple and label‐free approach to detect amyloidosis. Lattice corneal dystrophy was chosen as a model disease of amyloidosis. Morphological difference between normal and diseased human corneal biopsy samples can be easily recognized, proving that SHG can be a useful tool for disease diagnosis.     

Self‐assembled nanostructures of long‐acting GnRH analogs modified at position 7

It is well known that GnRH analogs can self‐assemble into amyloid fibrils and that the duration of action of GnRH analogs depends on the ability of the amyloid to slowly release active peptides. The aim of this study was to investigate the influence of the amino acid residues at position 7 of GnRH analogues on peptide self‐assembly. It was found that the dominant shape of the nanostructure can be changed when the structures of the residues at position 7 differ significantly from that of leucine in Degarelix. When the backbone length was extended (peptide 9), or the side chain of the residue at position 7 was replaced by an aromatic ring (peptide 6), or the rotation of the amide bond was restricted (peptide 8), the nanostructure changed from fibrils to vesicles. The results also indicate that the increasing hydrophilicity had little influence on the nanostructure morphology. In addition, a suitable release rate was found to play a more important role for the duration of the peptide action by maintaining the equilibrium between the drug concentration and the persistent release time, while the nanostructure shape was found to exert little influence on the duration of the peptide action. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Self‐Powered Gyroscope Ball Using a Triboelectric Mechanism

Healthcare monitoring systems can provide important health state information by monitoring the biomechanical parameter or motion of body segments. Triboelectric nanogenerators (TENGs) as self‐powered motion sensors have been developed rapidly to convert external mechanical change into electrical signal. However, research effort on using TENGs for multiaxis acceleration sensing is very limited. Moreover, TENG has not been demonstrated for rotation sensing to date. Herein, for the first time, a 3D symmetric triboelectric nanogenerator‐based gyroscope ball (T‐ball) with dual capability of energy harvesting and self‐powered sensing is proposed for motion monitoring including multiaxis acceleration and rotation. The T‐ball can harvest energy under versatile scenarios and function as self‐powered 3D accelerometer with sensitivity of 6.08, 5.87, and 3.62 V g ^?1 . Furthermore, the T‐ball can serve as a self‐powered gyroscope for rotation sensing with sensitivity of 3.5 mV s^o?1. It shows good performance in hand motion recognition and human activity state monitoring applications. The proposed T‐ball as a self‐powered gyroscope for advanced motion sensing can pave the way to a self‐powered, more accurate, and more complete motion monitoring system.     

Self‐assembly of pH and calcium dual‐responsive peptide‐amphiphilic hydrogel

Peptide‐based hydrogels have gained much interest for biomedical applications as a result of their biocompatibility. Herein, we reported a synthetic pH‐sensitive and calcium‐responsive peptide‐amphiphilic hydrogel. The sequences of the peptide amphiphiles were derived from the repeat‐in‐toxin (RTX) motif. At a certain peptide‐amphiphile concentration, self‐assembly was accompanied by the formation of a rigid, viscoelastic hydrogel at low pH or the presence of calcium ions. Circular dichroism spectra showed that the peptide amphiphiles adopted beta‐sheet structure. Meanwhile, as revealed by transmission electron microscopy, the peptide‐amphiphile self‐assembly was accompanied by the formation of long interconnected nanofibrillar superstructure. Material properties of the resulting peptide‐amphiphile hydrogel were characterized using oscillatory sheer rheology, and the storage modulus (G′) was found to be one order of magnitude higher than the loss modulus (G″), indicating a moderately rigid viscoelastic material. Furthermore, with systematical residue substitution, it was found that the aspartic acid within the repeat‐in‐toxin sequence of peptide amphiphiles was responsible for the pH and calcium selectivity. The environmental responsiveness, secondary structure, morphology, and mechanical nature of the peptide‐amphiphile hydrogel make it a possible material candidate for biomedical and engineering application. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Triblock‐Terpolymer‐Directed Self‐Assembly of Mesoporous TiO2: High‐Performance Photoanodes for Solid‐State Dye‐Sensitized Solar Cells

A new self‐assembly platform for the fast and straightforward synthesis of bicontinuous, mesoporous TiO₂ films is presented, based on the triblock terpolymer poly(isoprene ‐ b ‐ styrene ‐ b ‐ ethylene oxide). This new materials route allows the co‐assembly of the metal oxide as a fully interconnected minority phase, which results in a highly porous photoanode with strong advantages over the state‐of‐the‐art nanoparticle‐based photoanodes employed in solid‐state dye‐sensitized solar cells. Devices fabricated through this triblock terpolymer route exhibit a high availability of sub‐bandgap states distributed in a narrow and low enough energy band, which maximizes photoinduced charge generation from a state‐of‐the‐art organic dye, C220. As a consequence, the co‐assembled mesoporous metal oxide system outperformed the conventional nanoparticle‐based electrodes fabricated and tested under the same conditions, exhibiting solar power‐conversion efficiencies of over 5%.     

Liquid Crystallinity as a Self‐Assembly Motif for High‐Efficiency,Solution‐Processed,Solid‐State Singlet Fission Materials

Solution and solution‐deposited thin films of the discotic liquid crystalline electron acceptor–donor–acceptor (A‐D‐A) p‐type organic semiconductor FHBC(TDPP)₂, synthesized by coupling thienyl substituted diketopyrrolopyrrole (TDPP) onto a fluorenyl substituted hexa‐peri‐hexabenzocoronene (FHBC) core, are examined by ultrafast and nanosecond transient absorption spectroscopy, and time‐resolved photoluminescence studies to examine their ability to support singlet fission (SF). Grazing incidence wide‐angle X‐ray (GIWAX) studies indicate that as‐cast thin films of FHBC(TDPP)₂ are “amorphous,” while hexagonal packed discotic liquid crystalline films evolve during thermal annealing. SF in as‐cast thin films is observed with an ≈150% triplet generation yield. Thermally annealing the thin films improves SF yields up to 170%. The as‐cast thin films show no long‐range order, indicating a new class of SF material where the requirement for local order and strong near neighbor coupling has been removed. Generation of long‐lived triplets (µs) suggests that these materials may also be suitable for inclusion in organic solar cells to enhance performance.     

Self‐assembling study of sarcolipin and its mutants in multiple molecular dynamic simulations

The Sarcolipin (SLN) is a single trans‐membrane protein that can self‐assembly to dimer and oligomer for playing importantphysiological function. In this work, we addressed the dimerization of wild type SLN (wSLN) and its mutants (mSLNs) – I17A and I20A, using both coarse‐grained (CG) and atomistic (AT) molecular dynamics (MD) simulations. Our results demonstrated that wSLN homodimer assembled as a left‐handed helical complex, while mSLNs heterodimers assembled as right‐handed complexes. Analysis of residue‐residue contacts map indicated that isoleucine (Ile)‐leucione (Leu) zipper domain played an important role in dimerization. The potential of mean force (PMF) demonstrated that wSLN homodimer was more stable than mSLNs heterodimers. Meanwhile, the mSLNs heterodimers preferred right‐handed rather than left‐handed helix. AT‐MD simulations for wSLN and mSLNs were also in line with CG‐MD simulations. These results provided the insights for understanding the mechanisms of SLNs self‐assembling. Proteins 2017; 85:1065–1077. © 2017 Wiley Periodicals, Inc.     

Directed Self‐Assembly of MOF‐Derived Nanoparticles toward Hierarchical Structures for Enhanced Catalytic Activity in CO Oxidation

The controllable self‐assembly of nanomaterials remains a great challenge in nanotechnological applications, especially for the hierarchical structure with high complexity. Herein, by taking the advantage of highly dispersed metal nodes and mild thermal stability of metal‐organic frameworks (MOFs), the self‐assembly of nanoparticles is directed from MOFs to construct CuO hierarchical structures, which have an inherited octahedral framework consisting of the microspheres, nanowires, and polyhedrons, respectively. Unlike the conventional self‐assembly in a solution media (such as solvent and molten solid), the assembly in this work is the first demonstration through a solution‐free approach. Moreover, compared to the general MOF‐derived CuO octahedron, the assembled hierarchical CuO structure exhibits much enhanced catalytic activity in CO oxidation thanks to the exposure of more active sites during the assembly.     

Self‐Assembled 2D Perovskite Layers for Efficient Printable Solar Cells

2D organic–inorganic hybrid Ruddlesden–Popper perovskites have emerged recently as candidates for the light‐absorbing layer in solar cell technology due largely to their impressive operational stability compared with their 3D‐perovskite counterparts. The methods reported to date for the preparation of efficient 2D perovksite layers for solar cells involve a nonscalable spin‐coating step. In this work, a facile, spin‐coating‐free, directly scalable drop‐cast method is reported for depositing precursor solutions that self‐assemble into highly oriented, uniform 2D‐perovskite films in air, yielding perovskite solar cells with power conversion efficiencies (PCE) of up to 14.9% (certified PCE of 14.33% ± 0.34 at 0.078 cm²). This is the highest PCE to date for a solar cell with 2D‐perovskite layers fabricated by nonspin‐coating method. The PCEs of the cells display no evidence of degradation after storage in a nitrogen glovebox for more than 5 months. 2D‐perovskite layer deposition using a slot‐die process is also investigated for the first time. Perovskite solar cells fabricated using batch slot‐die coating on a glass substrate or R2R slot‐die coating on a flexible substrate produced PCEs of 12.5% and 8.0%, respectively.     

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/H₂O. 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.     

Self‐assembly and chiroptical properties in supramolecular complexes of adenosine phosphates and guanidinium‐bispyrene

Supramolecular systems that respond to the hydrolysis of adenosine phosphates (APs) are attractive for biosensing and to fabricate bioinspired self‐assembled materials. Here, we report on the formation of supramolecular complexes between an achiral guanidinium derivative bearing two pyrene moieties, with each of the three adenosine phosphates: AMP, ADP, and ATP. By combining results from circular dichroism spectroscopy and molecular modeling simulations, we explore the induced chirality, the dynamics of the complexes, and the interactions at play, which altogether provide insights into the supramolecular self‐assembly between APs and the guanidinium‐bispyrene. Finally, we identify the chiroptical signals of interest in mixtures of the guanidinium derivative with the three APs in different proportions. This study constitutes a basis to evolve toward a chiroptical detection of the hydrolysis of APs based on organic supramolecular probes.     

Self‐assembly of short peptides composed of only aliphatic amino acids and a combination of aromatic and aliphatic amino acids

The morphology of structures formed by the self‐assembly of short N‐terminal t‐butyloxycarbonyl (Boc) and C‐terminal methyl ester (OMe) protected and Boc‐deprotected hydrophobic peptide esters was investigated. We have observed that Boc‐protected peptide esters composed of either only aliphatic hydrophobic amino acids or aliphatic hydrophobic amino acids in combination with aromatic amino acids, formed highly organized structures, when dried from methanol solutions. Transmission and scanning electron microscopic images of the peptides Boc‐Ile‐Ile‐OMe, Boc‐Phe‐Phe‐Phe‐Ile‐Ile‐OMe and Boc‐Trp‐Ile‐Ile‐OMe showed nanotubular structures. Removal of the Boc group resulted in disruption of the ability to form tubular structures though spherical aggregates were formed. Both Boc‐Leu‐Ile‐Ile‐OMe and H‐Leu‐Ile‐Ile‐OMe formed only spherical nanostructures. Dynamic light scattering studies showed that aggregates of varying dimensions were present in solution suggesting that self‐assembly into ordered structures is facilitated by aggregation in solution. Fourier transform infrared spectroscopy and circular dichroism spectroscopy data show that although all four of the protected peptides adopt well‐defined tertiary structures, upon removal of the Boc group, only H‐Phe‐Phe‐Phe‐Ile‐Ile‐OMe had the ability to adopt β‐structure. Our results indicate that hydrophobic interaction is a very important determinant for self‐assembly and presence of charged and aromatic amino acids in a peptide is not necessary for self‐assembly. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.     

Self‐Assemble and In Situ Formation of Ni1−xFexPS3 Nanomosaic‐Decorated MXene Hybrids for Overall Water Splitting

Herein, the authors present the development of novel 0D–2D nanohybrids consisting of a nickel‐based bimetal phosphorus trisulfide (Ni_1?xFe_xPS₃) nanomosaic that decorates on the surface of MXene nanosheets (denoted as NFPS@MXene). The nanohybrids are obtained through a facile self‐assemble process of transition metal layered double hydroxide (TMLDH) on MXene surface; followed by a low temperature in situ solid‐state reaction step. By tuning the Ni:Fe ratio, the as‐synthesized NFPS@MXene nanohybrids exhibit excellent activities when tested as electrocatalysts for overall water splitting. Particularly, with the initial Ni:Fe ratio of 7:3, the obtained Ni_0.7Fe_0.3PS₃@MXene nanohybrid reveals low overpotential (282 mV) and Tafel slope (36.5 mV dec^?1) for oxygen evolution reaction (OER) in 1 m KOH solution. Meanwhile, the Ni_0.9Fe_0.1PS₃@MXene shows low overpotential (196 mV) for the hydrogen evolution reaction (HER) in 1 m KOH solution. When integrated for overall water splitting, the Ni_0.7Fe_0.3PS₃@MXene || Ni_0.9Fe_0.1PS₃@MXene couple shows a low onset potential of 1.42 V and needs only 1.65 V to reach a current density of 10 mA cm^?2, which is better than the all noble metal IrO₂ || Pt/C electrocatalyst (1.71 mV@10 mA cm^?2). Given the chemical versatility of Ni_1?xFe_xPS₃ and the convenient self‐assemble process, the nanohybrids demonstrated in this work are promising for energy conversion applications.