Versatile Template Research Articles

Artificial Helical Screws of 2D Materials with Archimedean Spiral Arrangement

AbstractHelix structures, which are frequently observed in nature, act as versatile structural templates for complex functionalities with asymmetry and anisotropy. However, atomically thin 2D materials, including graphene, transition metal dichalcogenides (TMDs), and MXenes, do not have inherent chirality in their planar geometry and cannot easily form such a structure. This study presents the macroscopic self‐assembly of 2D materials for helical screws with an Archimedean spiral arrangement. The naturally triggered spontaneous rotation upon the 1D fiber assembly of 2D materials forms helical screws consisting of multiple helices and perversions. For a clear understanding of the morphological evolution of helical screws, variations in the helical pitch and angle are systematically analyzed considering thermodynamic and kinetic conditions. Subsequently, the influence of spontaneous helix formation on the properties of the 2D assembled fibers is investigated in terms of the solvent‐driven actuator performance and electrical and electrothermal properties. The suggested approach provides a new perspective on the directed self‐assembly of inherently achiral 2D materials toward chiral helix formation.

Development of a Universal Cloning System for Reverse Genetics of Human Enteroviruses.

Enteroviruses (EVs) have been associated with several human diseases. Due to their continuous emergence and divergence, EV species have generated more than 100 types and recombinant strains, increasing the public health threat caused by them. Hence, an efficient and universal cloning system for reverse genetics (RG) of highly divergent viruses is needed to understand the molecular mechanisms of viral pathology and evolution. In this study, we generated a versatile human EV whole-genome cDNA template by enhancing the template-switching method and designing universal primers capable of simultaneous cloning and rapid amplification of cDNA ends (RACE)-PCR of EVs. Moreover, by devising strategies to overcome limitations of previous cloning methods, we simplified significant cloning steps to be completed within a day. Of note, we successfully verified our efficient universal cloning system enabling RG of a broad range of human EVs, including EV-A (EV-A71), EV-B (CV-B5, ECHO6, and ECHO30), EV-C (CV-A24), and EV-D (EV-D68), with viral titers and phenotypes comparable to those of their wild types. This rapid and straightforward universal EV cloning strategy will help us elucidate molecular characteristics, pathogenesis, and applications of a broad range of EV serotypes for further development of genetic vaccines and delivery tools using various replication systems. IMPORTANCE Due to the broad spread, incidence, and genetic divergence of enteroviruses (EVs), it has been challenging to deal with this virus that causes severe human diseases, including aseptic meningitis, myocarditis, encephalitis, and poliomyelitis. Therefore, an efficient and universal cloning system for the reverse genetics of highly divergent EVs contributes to an understanding of the viral pathology and molecular mechanisms of evolution. We have simplified the important cloning steps, hereby enhancing the template-switching method and designing universal primers, which enable the important cloning steps to be completed in a day. We have also successfully demonstrated recovery of a broad range of human EVs, including EV-A to -D types, using this advanced universal cloning system. This rapid and robust universal EV cloning strategy will aid in elucidating the molecular characteristics, pathogenesis, and applications of a wide range of EVs for further development of genetic vaccines and antiviral screening using various replication systems.

MIL-68 (In) and ZIF-8 assisted construction of n-n heterostructure for the effective sensing of trace-level ozone

The crucial challenge to exploit effective ozone (O3) gas sensors lies in developing novel functional sensing materials to meet the requirement of trace-level detection threshold (50 ppb). Metal oxide semiconductors (MOSs) with controllable heterogenous composites as high-performance sensing layers are expected to break through this bottleneck. This work proposes the hybridization of MIL-68 (In) and ZIF-8, which are employed as dual metal organic frameworks (MOFs) sacrificial templates to design n-n heterostructures. The derived In2O3 backbone showed a hexagonal prismatic structure with a large aspect ratio. The robust architecture enabled the uniform decoration of mass of ZnO nanoparticles (NPs) on the surfaces without the damage of high porosity for the gas diffusion. Consequently, the optimal sensor with appropriate ZnO NPs loading amount exhibited trace O3 detection ability as low as 15 ppb, which was attributed to the smart design of n-n heterostructure, rich active sites and improved oxygen-adsorbing capacity. Thus, this work inspires a new way to utilize the versatile dual MOFs template for constructing heterogenous composites as O3 sensing materials.

A new and versatile template towards vertically oriented nanopillars and nanotubes.

Vertically oriented nanostructures bring unparalleled high surface area, light trapping capability, and high device density to electronic, optoelectronic, and energy storage devices. However, general methods to prepare such structures remain sparse and are typically based on anodized metal oxide templates. Here, we demonstrate a new approach: using vertically oriented tetraaniline nanopillar arrays as templates for creating nanopillars and nanotubes of other materials. The tetraaniline templates are scalable and easy to prepare. Vertical arrays of a variety of materials can be created by directly coating them onto the tetraaniline nanopillars via vapor, solution, or electrodeposition. Since the tetraaniline template is encased within the target material, it does not require post-deposition removal, thus enabling vertical structure formation of sensitive materials. Conversely, removal of the encased tetraaniline template provides vertically oriented nanotube arrays in a lost-wax-type operation. The resulting vertical structures exhibit a high degree of orientation and height uniformity, with tunable feature size, spacing, and array density. Furthermore, the deposition location and shape of the vertical arrays can be patterned at a resolution of 3 μm. Collectively, these attributes should broaden the material repertoire for vertically oriented structures, and lead to advancements in energy storage, electronics, and optoelectronics.

BSA-templated synthesis of Ir/Gd bimetallic oxide nanotheranostics for MR/CT imaging-guided photothermal and photodynamic synergistic therapy.

Precision medicine urges the development of theranostics which can efficiently integrate precise diagnosis and effective therapy. In this study, a facile synthesis of Ir/Gd bimetallic oxide nanotheranostics (termed BSA@Gd2O3/IrO2 NPs) with good biocompatibility was demonstrated using a biomineralization method where bovine serum albumin (BSA) served as a versatile template. BSA@Gd2O3/IrO2 NPs exhibited high longitudinal relaxivity (5.2 mM-1 s-1) and X-ray absorption capability (14.5 Hu mM-1), illustrating them to be a good contrast agent for magnetic resonance (MR) and computed tomography (CT) dual-modal imaging. Moreover, BSA@Gd2O3/IrO2 NPs can act as not only a photothermal conversion agent with ultrahigh efficiency (66.7%) as well as a good photosensitizer, but also an effective catalase to decompose endogenous H2O2 to produce O2, thus relieving hypoxia and enhancing the phototherapeutic effect. Both in vitro and in vivo experiments demonstrated the high effectiveness of BSA@Gd2O3/IrO2 NPs in MR/CT dual-modal imaging and photothermal and photodynamic synergistic tumor treatments. This work sheds new light on the development of versatile nanotheranostic systems using mild and robust biomineralization methods.

Atroposelective brominations to access chiral biaryl scaffolds using high-valent Pd-catalysis.

Compounds featuring atropisomerism are ubiquitous in natural products, therapeutics, advanced materials, and asymmetric synthesis. However, stereoselective preparation of these compounds presents many synthetic challenges. This article introduces streamlined access to a versatile chiral biaryl template through C-H halogenation reactions employing high-valent Pd catalysis in combination with chiral transient directing groups. This methodology is highly scalable, insensitive to moisture and air, and proceeds, in select cases, with Pd-loadings as low as 1 mol%. Chiral mono-brominated, dibrominated, and bromochloro biaryls are prepared in high yield and excellent stereoselectivity. These serve as remarkable building blocks bearing orthogonal synthetic handles for a gamut of reactions. Empirical studies elucidated regioselective C-H activation to be predicated on the oxidation state of Pd and diverging site-halogenation to result from cooperative effects of Pd and oxidant.

Hydrazine High-Performance Oxidation and Sensing Using a Copper Oxide Nanosheet Electrocatalyst Prepared via a Foam-Surfactant Dual Template.

This work demonstrates hydrazine electro-oxidation and sensing using an ultrathin copper oxide nanosheet (CuO-NS) architecture prepared via a versatile foam-surfactant dual template (FSDT) approach. CuO-NS was synthesised by chemical deposition of the hexagonal surfactant Brij®58 liquid crystal template containing dissolved copper ions using hydrogen foam that was concurrently generated by a sodium borohydride reducing agent. The physical characterisations of the CuO-NS showed the formation of a two-dimensional (2D) ultrathin nanosheet architecture of crystalline CuO with a specific surface area of ~39 m2/g. The electrochemical CuO-NS oxidation and sensing performance for hydrazine oxidation revealed that the CuO nanosheets had a superior oxidation performance compared with bare-CuO, and the reported state-of-the-art catalysts had a high hydrazine sensitivity of 1.47 mA/cm2 mM, a low detection limit of 15 μM (S/N = 3), and a linear concentration range of up to 45 mM. Moreover, CuO-NS shows considerable potential for the practical use of hydrazine detection in tap and bottled water samples with a good recovery achieved. Furthermore, the foam-surfactant dual template (FSDT) one-pot synthesis approach could be used to produce a wide range of nanomaterials with various compositions and nanoarchitectures at ambient conditions for boosting the electrochemical catalytic reactions.

Postsynthetic Thiol-Induced Reshaping of Copper Sulfide Nanoparticles

Nanoparticles of copper sulfide, including roxbyite Cu1.8S, are important materials for many applications, and they also serve as versatile templates for cation exchange reactions that transform them into derivative metal sulfide compounds and complex heterostructures. The sizes and shapes of roxbyite nanoparticles are generally determined during synthesis, and their morphologies are retained during postsynthetic modifications such as cation exchange. Here, we demonstrate postsynthetic morphological modification of roxbyite nanoparticles by treating them with 1-dodecanethiol (1-DDT) and tert-dodecanethiol (t-DDT) at temperatures ranging from 90 to 160 °C. These thiols, which are typically used as ligands and/or sulfur reagents in nanoparticle synthesis, induce morphological reshaping while maintaining composition, crystal structure, and particle volume. For example, 56 nm × 21 nm roxbyite nanorods transform to 32 nm spherical particles in the presence of 1-DDT at 130 °C for two or more hours. The nanorods progressively decrease in length and increase in width, forming a series of ellipsoids having tunable aspect ratios at intermediate time points. Control experiments point to a single-crystal-to-single-crystal pathway that involves material diffusion and migration, which can be accelerated by increasing the density of cation vacancies in the nanoparticles. Because of this pathway, the thiol-induced morphology changes are selective to the copper sulfide regions of heterostructured nanorods containing roxbyite and ZnS, Co9S8, or CuInS2 made using partial cation exchange reactions, providing access to a library of derivative nanoparticles having otherwise inaccessible morphologies.

Tannic Acid as a Versatile Template for Silica Monoliths Engineering with Catalytic Gold and Silver Nanoparticles.

Tannic acid in alkaline solutions in which sol-gel synthesis is usually performed with tetraethoxysilane is susceptible to various modifications, including formation of reactive radicals, oxidation under the action of atmospheric oxygen, self-association, and self-polymerization. Here, a precursor with ethylene glycol residues instead of ethanol was used, which made it possible to synthesize bionanocomposites of tannic acid and silica in one stage in neutral media under normal conditions without the addition of acid/alkali and organic solvents. Silica was fabricated in the form of optically transparent monoliths of various shapes with 2-4 nm pores, the radius of which well correlated with the size of a tannic acid macromolecule in a non-aggregated state. Polyphenol, which was remained in pores of silica matrix, served then as reducing agent to synthesize in situ gold and silver nanoparticles. As shown, these Au@SiO2 and Ag@SiO2 nanocomposites possessed localized surface plasmon resonance and high catalytic activity.

In situ observation of compressive deformation of an interconnected network of zinc oxide tetrapods

Zinc oxide tetrapods have remarkable functional and mechanical properties with potential applications in different fields including nanoelectronic and optoelectronic sensing, functional composites and coatings, as well as energy harvesting and storage. Based on the 3D shape of these microparticles, they can be assembled into highly porous (up to 98%) macroscopic ceramic framework structures that can be utilized as a versatile template for the fabrication of other multi-scaled foam-like materials. Here we investigated the three-dimensional structure of low density interconnected zinc oxide tetrapod networks by high resolution X-ray computed tomography. In situ observations during mechanical loading show inhomogeneous development of anelastic strain (damage) during compression, and homogeneous elastic recovery on unloading. Individual tetrapods are observed to deform by arm rotation to accommodate strain.

Boosters for adeno-associated virus (AAV) vector (r)evolution

Adeno-associated virus (AAV) is one of the most exciting and most versatile templates for engineering of gene-delivery vectors for use in human gene therapy, owing to the existence of numerous naturally occurring capsid variants and their amenability to directed molecular evolution. As a result, the field has witnessed an explosion of novel “designer” AAV capsids and ensuing vectors over the last two decades, which have been isolated from comprehensive capsid libraries generated through technologies such as DNA shuffling or peptide display, and stratified under stringent positive and/or negative selection pressures. Here, we briefly highlight a panel of recent, innovative and transformative methodologies that we consider to have exceptional potential to advance directed AAV capsid evolution and to thereby accelerate AAV vector revolution. These avenues comprise original technologies for (i) barcoding and high-throughput screening of individual AAV variants or entire capsid libraries, (ii) selection of transduction-competent AAV vectors on the DNA level, (iii) enrichment of expression-competent AAV variants on the RNA level, as well as (iv) high-resolution stratification of focused AAV capsid libraries on the single-cell level. Together with other emerging AAV engineering stratagems, such as rational design or machine learning, these pioneering techniques promise to provide an urgently needed booster for AAV (r)evolution.

Design and Synthesis of Arylpiperazine Serotonergic/Dopaminergic Ligands with Neuroprotective Properties.

Long-chain arylpiperazine scaffold is a versatile template to design central nervous system (CNS) drugs that target serotonin and dopamine receptors. Here we describe the synthesis and biological evaluation of ten new arylpiperazine derivatives designed to obtain an affinity profile at serotonin 5-HT1A, 5-HT2A, 5-HT7 receptor, and dopamine D2 receptor of prospective drugs to treat the core symptoms of autism spectrum disorder (ASD) or psychosis. Besides the structural features required for affinity at the target receptors, the new compounds incorporated structural fragments with antioxidant properties to counteract oxidative stress connected with ASD and psychosis. All the new compounds showed CNS MultiParameter Optimization score predictive of desirable ADMET properties and cross the blood–brain barrier. We identified compound 12a that combines an affinity profile compatible with antipsychotic activity (5-HT1A Ki = 41.5 nM, 5-HT2A Ki = 315 nM, 5-HT7 Ki = 42.5 nM, D2 Ki = 300 nM), and compound 9b that has an affinity profile consistent with studies in the context of ASD (5-HT1A Ki = 23.9 nM, 5-HT2A Ki = 39.4 nM, 5-HT7 Ki = 45.0 nM). Both compounds also had antioxidant properties. All compounds showed low in vitro metabolic stability, the only exception being compound 9b, which might be suitable for studies in vivo.

Cationic peptides template the assembly of polyoxometalates into ultrathin nanosheets with in-plane ordered arrangements.

Ultrathin polyoxometalate nanosheets with an in-plane alignment have been constructed in aqueous solution with the assistance of cationic peptides. Different POMs varying in topology, size, and charges could be templated into ordered 2D nanostructures based on this generalized approach, allowing the fabrication of customizable 2D materials.

Textural control of ionosilicas by ionic liquid templating.

Due to their unique self-assembly properties, ionic liquids (ILs) are versatile soft templates for the formation of mesoporous materials. Here, we report the use of ionic liquids as soft templates for the straightforward formation of mesoporous ionosilica phases. Ionosilicas are highly polyvalent functional materials that are constituted of ionic building blocks that are covalently immobilized within a silica hybrid matrix. Ionosilicas have attracted significant interest in the last few years due to their high potential for applications in water treatment and upgrading, separation and drug delivery. The straightforward and reproducible formation of mesoporous ionosilica phases is therefore highly desirable. In this context, we report the formation of mesoporous ionosilica phases via non-hydrolytic sol-gel procedures in the presence of ionic liquids. Ionic liquids appear as particularly versatile templates for mesoporous ionosilicas due to their high chemical similarity and affinity between ILs and silylated ionic precursors. We therefore studied the textures of the resulting ionosilica phases, after IL elimination, using nitrogen sorption, small angle X-ray scattering (SAXS) and transmission and scanning electron microscopies. All these techniques give concordant results and show that the textures of ionosilica scaffolds in terms of specific surface area, pore size, pore size distribution and connectivity can be efficiently controlled by the nature and the quantity of the ionic liquid that is used in the ionothermal sol-gel procedure.

Recent Progress of Magnetically Actuated DNA Micro/Nanorobots.

In the past few decades, the field of DNA origami-based micro/nanotechnology has developed dramatically and spawned attention increasingly, as its high integrality, rigid structure, and excellent resistance ability to enzyme digestion. Many two-dimensional and three-dimensional DNA nanostructures coordinated with optical, chemical, or magnetic triggers have been designed and assembled, extensively used as versatile templates for molecular robots, nanosensors, and intracellular drug delivery. The magnetic field has been widely regarded as an ideal driving and operating system for micro/nanomaterials, as it does not require high-intensity lasers like light control, nor does it need to change the chemical composition similar to chemical activation. Herein, we review the recent achievements in the induction and actuation of DNA origami-based nanodevices that respond to magnetic fields. These magnetic actuation-based DNA nanodevices were regularly combined with magnetic beads or gold nanoparticles and applied to generate single-stranded scaffolds, assemble various DNA nanostructures, and purify specific DNA nanostructures. Moreover, they also produced artificial magnetism or moved regularly driven by external magnetic fields to explain deeper scientific issues.

Conversion of Whey Protein Aerogel Particles into Oleogels: Effect of Oil Type on Structural Features.

Protein aerogel particles prepared by supercritical-CO2-drying (SCD) of ground whey protein (WP) hydrogels (20% w/w, pH 5.7) were converted into oleogels by dispersion in selected edible oils (castor, cod liver, corn, flaxseed, MCT, peanut and sunflower oil). The obtained oleogels were analysed for oil content, microstructure, rheological properties, and ATR-FTIR spectra. Except for castor oil, solid-like, plastic materials with comparable composition (80% oil, 20% WP) and rheological properties (G′~3.5 × 105 Pa, G″~0.20 × 105 Pa, critical stress~800 Pa, tanδ~0.060) were obtained. Optical and confocal microscopy showed that the generated structure was associated with the capillary-driven absorption of oil into the porous aerogel particles interconnected via particle-particle interactions. In this structure, the oil was stably entrapped. Results evidenced the reduced role of edible oil characteristics with the exception of castor oil, whose high polarity probably favoured particle–oil interactions hindering particle networking. This work demonstrates that WP aerogels could be regarded as versatile oleogel templates allowing the structuring of many edible oils into solid-like materials.

Nanometals Templated by Tobacco Mosaic Virus Coat Protein with Enhanced Catalytic Activity

Bio-nano hybrid materials feature eco-friendly synthesis, various self-assembly patterns and numerous possibilities of surface functionalization. Owing to these unique advantages, biological scaffolds have been be regarded as green alternatives to fabricate metallic nanomaterials for catalytic applications. In this study, a bulky tobacco mosaic virus coat protein (TMVCP) has been employed as a versatile template to synthesize nanometals (Pd, Pt and Au) in alkaline buffer at room temperature. Protein-functionalized nanoparticles (NPs) with ca. 3 nm in diameter were obtained with uniform size distributions. These materials are green catalytic systems with exceptional performance for small organic molecule transformations in water. Remarkably, while Au NPs showed rapid kinetics in 4-nitrophenol reduction (rate constant with Au NPs: 0.01862 s-1), Pd NPs exhibited superior catalytic activity towards hydrogenation of allyl alcohol (Turnover frequency of Pd NPs: 6382 ± 200 mol product (mol Pd * h)-1) and a set of derivatives. The enhanced catalytic performance is strongly related to the protein ligand. To ascertain the protein structure-function effect on the catalytic performance, an in-depth analysis was performed for the TMVCP-Pd NP system via molecular dynamic (MD) simulations. Our results suggest that due to the moderate interaction between Pd and protein and the steric hindrance of the bulky protein, a large portion of the Pd NP surface remains approachable for the reactant molecules, thus resulting in enhanced reaction rate.

Evaporation kinetics in highly porous tetrapodal zinc oxide networks studied using in situ SR\xb5CT

Tetrapodal zinc oxide (t-ZnO) is used to fabricate polymer composites for many different applications ranging from biomedicine to electronics. In recent times, macroscopic framework structures from t-ZnO have been used as a versatile sacrificial template for the synthesis of multi-scaled foam structures from different nanomaterials such as graphene, hexagonal boron nitride or gallium nitride. Many of these fabrication methods rely on wet-chemical coating processes using nanomaterial dispersions, leading to a strong interest in the actual coating mechanism and factors influencing it. Depending on the type of medium (e.g. solvent) used, different results regarding the homogeneity of the nanomaterial coating can be achieved. In order to understand how a medium influences the coating behavior, the evaporation process of water and ethanol is investigated in this work using in situ synchrotron radiation-based micro computed tomography (SRµCT). By employing propagation-based phase contrast imaging, both the t-ZnO network and the medium can be visualized. Thus, the evaporation process can be monitored non-destructively in three dimensions. This investigation showed that using a polar medium such as water leads to uniform evaporation and, by that, a homogeneous coating of the entire network.

Nitrogen-Doped Carbon Composites with Ordered Macropores and Hollow Walls.

Metal-organic frameworks provide versatile templates for the fabrication of various metal/carbon materials, but most of the derived composites possess only microspores, limiting the accessibility of embedded active sites. Herein, we report the construction of cobalt/nitrogen-doped carbon composites with a three-dimensional (3D) ordered macroporous and hollow-wall structure (H-3DOM-Co/NC) using a single-crystal ordered macropore (SOM)-ZIF-8@ZIF-67 as precursor. During the pyrolysis, the interconnected macroporous structure of SOM-ZIF-8@ZIF-67 is mostly preserved, whereas the pore wall achieves a solid-to-hollow transformation with Co nanoparticles formed in the hollow walls. The 3D-ordered macroporous carbon skeleton may effectively promote long-range mass transfer and the hollow wall can facilitate local accessibility of active sites. This unique structure can greatly boost its catalytic activity in the selective hydrogenation of biomass-derived furfural to cyclopentanol, much superior to its counterparts without this well-designed hierarchically porous structure.

Nitrogen‐Doped Carbon Composites with Ordered Macropores and Hollow Walls

AbstractMetal‐organic frameworks provide versatile templates for the fabrication of various metal/carbon materials, but most of the derived composites possess only microspores, limiting the accessibility of embedded active sites. Herein, we report the construction of cobalt/nitrogen‐doped carbon composites with a three‐dimensional (3D) ordered macroporous and hollow‐wall structure (H‐3DOM‐Co/NC) using a single‐crystal ordered macropore (SOM)‐ZIF‐8@ZIF‐67 as precursor. During the pyrolysis, the interconnected macroporous structure of SOM‐ZIF‐8@ZIF‐67 is mostly preserved, whereas the pore wall achieves a solid‐to‐hollow transformation with Co nanoparticles formed in the hollow walls. The 3D‐ordered macroporous carbon skeleton may effectively promote long‐range mass transfer and the hollow wall can facilitate local accessibility of active sites. This unique structure can greatly boost its catalytic activity in the selective hydrogenation of biomass‐derived furfural to cyclopentanol, much superior to its counterparts without this well‐designed hierarchically porous structure.