3D Assembly Research Articles

Evolution of Electrocatalytic CO2 Reduction Activity Induced by Charge Segregation in Atomically Precise AuAg Nanoclusters Based on Icosahedral M13 Unit 3D Assembly.

The precise self-assembly of building blocks at atomic level provides the opportunity to achieve clusters with advanced catalytic properties. However, most of the current self-assembled materials are fabricated by 1/2D assembly of blocks. High dimensional (that is, 3D) assembly is widely believed to improve the performance of cluster. Herein, the effect of 3D assembly on the activity for electrocatalytic CO2 reduction reaction (CO2 RR) is investigated by using a range of clusters (Au8 Ag55 , Au8 Ag57 , Au12 Ag60 ) based on 3D assembly of M13 unit as models. Although three clusters have almost the same sizes and geometric structures, Au8 Ag55 exhibits the best CO2 RR performance due to the strong CO2 adsorption capacity and effective inhibition of H2 evolution competition reaction. The deep insight into the superior activity of Au8 Ag55 is the unique electronic structure attributed to the charge segregation. This study not only demonstrates that the assembly mode greatly affects the catalytic activity, but also offers an idea for rational designing and precisely constructing catalysts with controllable activities.

Highly Stable Triangular Single‐Layer 2D Assemblies: Synthesis and Their Stimuli‐Responsive Elastic and Anisotropic Curling

AbstractSynthesis of highly stable two‐dimensional single‐layer assemblies (SLAs) is a key challenge in supramolecular science, especially those with long‐range molecular order and well‐defined morphology. Here, thin (thickness <2 nm) triangular AuI‐thiolate SLAs with high thermo‐, solvato‐ and mechano‐ stability have been synthesized via a double‐ligand co‐assembly strategy. Furthermore, the SLAs show assembly‐level elastic and anisotropic deformation responses to external stimuli as a result of the long‐range anisotropic molecular packing, which provides SLAs with new application potentials in bio‐mimic nanomechanics.

Highly Stable Triangular Single-Layer 2D Assemblies: Synthesis and Their Stimuli-Responsive Elastic and Anisotropic Curling.

Synthesis of highly stable two-dimensional single-layer assemblies (SLAs) is a key challenge in supramolecular science, especially those with long-range molecular order and well-defined morphology. Here, thin (thickness <2 nm) triangular AuI -thiolate SLAs with high thermo-, solvato- and mechano- stability have been synthesized via a double-ligand co-assembly strategy. Furthermore, the SLAs show assembly-level elastic and anisotropic deformation responses to external stimuli as a result of the long-range anisotropic molecular packing, which provides SLAs with new application potentials in bio-mimic nanomechanics.

Structure Transformation and Morphologic Modulation of Supramolecular Frameworks for Nanoseparation and Enzyme Loading.

Supramolecular framework (SF) encourages the emergence of porous structures with molecular flexibility while the dimension and morphology controls are less involved even though critical factors are vital for various utilizations. Targeting this purpose, two isolated components are designed and their stepped combinations via ionic interaction, metal coordination, and hydrogen bond into framework assembly with two morphologic states are realized. The zinc coordination to an ionic complex of polyoxometalate with three cationic terpyridine ligands constructs 2D hexagonal SF structure. A further growth along perpendicular direction driven by hydrogen bonding between grafted mannose groups leads to 3D SF assemblies, providing a modulation superiority in one framework for multiple utilizations. The large area of multilayered SF sheet affords a filtration membrane for strict separation of nanoparticles/proteins under gently reduced pressures while the granular SF assembly demonstrates an efficient carrier to load and fix horse radish peroxidase with maintained activity for enzymatic catalysis.

2D Assembly of Atomically Oriented Gold Nanodisks Leads to Tunable Plasmonic Resonance

2D Assembly of Atomically Oriented Gold Nanodisks Leads to Tunable Plasmonic Resonance

3D Printed Polyimide Nanocomposite Aerogels for Electromagnetic Interference Shielding and Thermal Management

AbstractAerogels were listed among the top ten emerging technologies in chemistry by IUPAC in 2022. Their record‐breaking properties sparked the emergence of a thriving insulation market, but solutions are sought to promote additional applications. A 3D assembly process based on direct ink writing of “aerogel‐in‐aerogel” nanocomposites is presented. The printed polyimide‐silica aerogels are non‐brittle (E = 6.7 MPa) with a super‐insulating thermal conductivity (20.3 mW m−1 K−1) and high thermal stability (T5wt% 447 °C). In addition, they display excellent low‐loss dielectric properties and microwave transmission over all relevant communication bands and can be functionalized for electromagnetic interference (EMI) shielding. The high shape‐fidelity printing, combined with laser‐induced etching of thermally conductive graphene layers, enable precise thermal management for portable electronics or maintain an extreme temperature gradient (−40 to +50°C) across a millimeter‐scale partition.

Insight into the role of pseudo-halides as multiple hydrogen bond acceptors in the formation of supramolecular 1D assembly of di and trinuclear zinc complexes

In this manuscript we report the synthesis of two new zinc(II) complexes, [(DMSO)2 ZnL1Zn(NCS)2] (1), and [{(N3)ZnL2}2Zn(DMSO)2] (2) that were characterized by elemental and spectral analyses {H2L1 is 2,2-dimethyl-1,3-propanediylbis(iminomethylene)bis(phenol), and H2L2 is 1,2-propanediylbis(iminomethylene)bis(4-chlorophenol)}. The structures have been confirmed by single crystal X-ray diffraction analysis. Both complexes form 1D supramoelcular assemblies where the pseudohalides act as multiple H-bond acceptors (CH•••S,N and NH•••S,N). These assemblies have been analyzed theoretically using DFT calculations, and the energy associated to each contact has been estimated using the quantum theory of atoms-in-molecules. The importance of long-range van der Waals interactions is emphasized. This manuscript, where two new complexes are synthesized and the H-bonding contacts individually estimated, is expected to attract the attention not only of synthetic inorganic chemists, but also theoreticians and chemists working in crystal engineering and supramolecular chemistry.

Shell engineering in soft alginate-based capsules for culturing liver spheroids.

Functional interaction between cancer cells and the surrounding microenvironment is still not sufficiently understood, which motivates the tremendous interest for the development of numerous in vitro tumor models. Diverse parameters, for example, transport of nutrients and metabolites, availability of space in the confinement, etc. make an impact on the size, shape, and metabolism of the tumoroids. We demonstrate the fluidics-based low-cost methodology to reproducibly generate the alginate and alginate-chitosan microcapsules and apply it to grow human hepatoma (HepG2) spheroids of different dimensions and geometries. Focusing specifically on the composition and thickness of the hydrogel shell, permeability of the microcapsules was selectively tuned. The diffusion of the selected benchmark molecules through the shell has been systematically investigated using both, experiments and simulations, which is essential to ensure efficient mass transfer and/or filtering of the biochemical species. Metabolic activity of spheroids in microcapsules was confirmed by tracking the turnover of testosterone to androstenedione with chromatography studies in a metabolic assay. Depending on available space, phenotypically different 3D cell assemblies have been observed inside the capsules, varying in the tightness of cell aggregations and their shapes. Conclusively, we believe that our system with the facile tuning of the shell thickness and permeability, represents a promising platform for studying the formation of cancer spheroids and their functional interaction with the surrounding microenvironment.

Spin Polarization of Polyalanine Molecules in 2D and Dimer-Row Assemblies Adsorbed on Magnetic Substrates: The Role of Coupling, Chirality, and Coordination.

Propagation of electrons along helical molecules adsorbed on surfaces comes along with a robust spin polarization effect called chirality induced spin selectivity CISS. However, experiments on the molecular scale that allow a true correlation of spin effects with the molecular structure are quite rare. Here we have studied the structure of self-assembled chiral molecules and the electronic transmission and spin polarization of the current through the system by means of ambient scanning tunneling microscopy and spectroscopy in heterostructures of various α-helix polyalanine-based molecules (PA) adsorbed on Al2O3/Pt/Au/Co/Au substrates with perpendicular magnetic anisotropy. We have found a phase separation of the molecules into well-ordered enantiopure 2D hexagonal phases and quasi-1D heterochiral-dimer structures, which allows for the analysis of the spin polarization with almost atomic precision of PA in different phases. The spin polarization reaches up to 75% for chemisorbed molecules arranged in a hexagonal phase. On the contrary, for weakly coupled PA molecules without cysteine anchoring groups in a quasi-1D phase, a spin polarization of around 50% was found. Our results show that both the intermolecular interaction as well as the coupling to the substrate are important and point out that collective effects within the molecules and at the interfaces are required to achieve a high chiral induced spin selectivity.

Tissue Engineering Challenges for Cultivated Meat to Meet the Real Demand of a Global Market.

Cultivated meat (CM) technology has the potential to disrupt the food industry-indeed, it is already an inevitable reality. This new technology is an alternative to solve the environmental, health and ethical issues associated with the demand for meat products. The global market longs for biotechnological improvements for the CM production chain. CM, also known as cultured, cell-based, lab-grown, in vitro or clean meat, is obtained through cellular agriculture, which is based on applying tissue engineering principles. In practice, it is first necessary to choose the best cell source and type, and then to furnish the necessary nutrients, growth factors and signalling molecules via cultivation media. This procedure occurs in a controlled environment that provides the surfaces necessary for anchor-dependent cells and offers microcarriers and scaffolds that favour the three-dimensional (3D) organisation of multiple cell types. In this review, we discuss relevant information to CM production, including the cultivation process, cell sources, medium requirements, the main obstacles to CM production (consumer acceptance, scalability, safety and reproducibility), the technological aspects of 3D models (biomaterials, microcarriers and scaffolds) and assembly methods (cell layering, spinning and 3D bioprinting). We also provide an outlook on the global CM market. Our review brings a broad overview of the CM field, providing an update for everyone interested in the topic, which is especially important because CM is a multidisciplinary technology.

Biomolecular 1D Necklace-like Nanostructures Tailoring 2D Janus Interfaces for Controllable 3D Enteric Biomaterials.

Construction of well-ordered two-dimensional (2D) and three-dimensional (3D) assemblies using one-dimensional (1D) units is a hallmark of many biointerfaces such as skin. Mimicking the art of difunctional properties of biointerfaces, which skin exhibits as defense and shelter materials, has inspired the development of smart and responsive biomimetic interfaces. However, programming the long-range ordering of 1D base materials toward vigorous control over 2D and 3D hierarchical structures and material properties remains a daunting challenge. In this study, we put forward construction of 3D enteric biomaterials with a two-strata 2D Janus interface assembled from self-adaptation of 1D protein-polysaccharide nanostructures at an oil-water interface. The biomaterials feature a protein dermis accommodating oil droplets as a reservoir for bioactive compounds and a polysaccharide epidermis protecting them from gastric degradation. Furthermore, the epidermis can be fine-tuned with different thicknesses rendering enteric delivery of a bioactive cargo (coumarin-6) with controllable retention in the intestinal tract from 6 to 24 h. The results highlight a skin-inspired construction of enteric biomaterials by self-adaptation of 1D nanostructures at the oil-water interface toward 2D Janus biointerfaces and 3D microdevices, which can be tailored for intestinal treatments with intentional therapeutic efficacies.

Design, synthesis, and characterization of protein origami based on self-assembly of a brick and staple artificial protein pair

A versatile strategy to create an inducible protein assembly with predefined geometry is demonstrated. The assembly is triggered by a binding protein that staples two identical protein bricks together in a predictable spatial conformation. The brick and staple proteins are designed for mutual directional affinity and engineered by directed evolution from a synthetic modular repeat protein library. As a proof of concept, this article reports on the spontaneous, extremely fast and quantitative self-assembly of two designed alpha-repeat (αRep) brick and staple proteins into macroscopic tubular superhelices at room temperature. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM with staining agent and cryoTEM) elucidate the resulting superhelical arrangement that precisely matches the a priori intended 3D assembly. The highly ordered, macroscopic biomolecular construction sustains temperatures as high as 75 °C thanks to the robust αRep building blocks. Since the α-helices of the brick and staple proteins are highly programmable, their design allows encoding the geometry and chemical surfaces of the final supramolecular protein architecture. This work opens routes toward the design and fabrication of multiscale protein origami with arbitrarily programmed shapes and chemical functions.

Development and verification of a Monte Carlo two-step method for lead-based fast reactor neutronics analysis

With the rise of economic and safety standards for nuclear reactors, new concepts of Gen-IV reactors and modular reactors showed more complex designs that challenge current tools for reactor physics analysis. A Monte Carlo (MC) two-step method was proposed in this work. This calculation scheme uses the continuous-energy MC method to generate multi-group cross-sections from heterogeneous models. The multi-group MC method, which can adapt locally-heterogeneous models, is used in the core calculation step. This calculation scheme is verified using a Gen-IV modular lead-based fast reactor (LFR) benchmark case. The influence of homogenized patterns, scatter approximations, flux separable approximation, and local heterogeneity in core calculation on simulation results are investigated. Results showed that the cross-sections generated using the 3D assembly model with a locally heterogeneous representation of control rods lead to an accurate estimation with less than 270 pcm bias in core reactivity, 0.5% bias in control rod worth, and 1.5% bias on power distribution. The study verified the applicability of multi-group cross-sections generated with the MC method for LFR analysis. The study also proved the feasibility of multi-group MC in core calculation with local heterogeneity, which saves 85% time compared to the continuous-energy MC.

Magnetically Tunable One-Dimensional Plasmonic Photonic Crystals.

Integrating plasmonic resonance into photonic bandgap nanostructures promises additional control over their optical properties. Here, one-dimensional (1D) plasmonic photonic crystals with angular-dependent structural colors are fabricated by assembling magnetoplasmonic colloidal nanoparticles under an external magnetic field. Unlike conventional 1D photonic crystals, the assembled 1D periodic structures show angular-dependent colors based on the selective activation of optical diffraction and plasmonic scattering. They can be further fixed in an elastic polymer matrix to produce a photonic film with angular-dependent and mechanically tunable optical properties. The magnetic assembly enables precise control over the orientation of the 1D assemblies within the polymer matrix, producing photonic films with designed patterns displaying versatile colors from the dominant backward optical diffraction and forward plasmonic scattering. The combination of optical diffraction and plasmonic properties within a single system holds the potential for developing programmable optical functionalities for applications in various optical devices, color displays, and information encryption systems.

On the Advent of Super-Resolution Microscopy in the Realm of Polycomb Proteins.

The genomes of metazoans are organized at multiple spatial scales, ranging from the double helix of DNA to whole chromosomes. The intermediate genomic scale of kilobases to megabases, which corresponds to the 50-300 nm spatial scale, is particularly interesting, as the 3D arrangement of chromatin is implicated in multiple regulatory mechanisms. In this context, polycomb group (PcG) proteins stand as major epigenetic modulators of chromatin function, acting prevalently as repressors of gene transcription by combining chemical modifications of target histones with physical crosslinking of distal genomic regions and phase separation. The recent development of super-resolution microscopy (SRM) has strongly contributed to improving our comprehension of several aspects of nano-/mesoscale (10-200 nm) chromatin domains. Here, we review the current state-of-the-art SRM applied to PcG proteins, showing that the application of SRM to PcG activity and organization is still quite limited and mainly focused on the 3D assembly of PcG-controlled genomic loci. In this context, SRM approaches have mostly been applied to multilabel fluorescence in situ hybridization (FISH). However, SRM data have complemented the maps obtained from chromosome capture experiments and have opened a new window to observe how 3D chromatin topology is modulated by PcGs.

Structural Spectrum of 2D Materials in Solution: Toward Establishing 2D Assemblies’ Digital Factory

AbstractThe numerous hierarchical architectures of 2D assemblies endow them with a new dimension to realize novel properties. From theoretical perspective, freedoms stem from in‐plane and out‐plane mechanical properties of 2D materials separately, which makes 2D materials embrace more than one “persistence length” giving rise to the diverse morphologies. However, the understanding of 3D architecture formation in 2D assemblies is still in its infancy. In fact, there is even no theoretical classification or reference to help clarify structural difference among numerous experimental obtained 2D assemblies. Based on the theoretical model composed by 2D sheets and Lennard‐Jones liquids, solution concentration dependence of 2D materials conformation is systematically studied, and a ln K behavior is uncovered that can realize the theoretical conformation prediction of 2D materials. More importantly, the digital production line (solution processing procedure) is set up toward establishing the 2D assemblies’ digital factory. The obtained structures may provide a reference to 2D assemblies, which benefits the understanding of the structural difference among different experiments and even help to guide the experimental design of 2D assemblies with targeted architectures and properties.

Hyperbranched Au Nanocorals for SERS Detection of Dye Pollutants

Gold (Au) nanomaterials having branched morphologies are recently attracting interest as surface-enhanced Raman scattering (SERS) substrates due to the abundance of hot spot regions in their structures. However, they are typically prepared through laborious experimental protocols that often make use of hazardous and expensive chemical reagents. In this study, we explored the use of environmentally compatible and low-cost organic acids that are known to occur naturally in plants (e.g., ascorbic acid, oxalic acid, tartaric acid) as alternative reagents to render the process greener. Aside from being environmentally friendly, the methodology presented here is convenient, direct, rapid, and inexpensive. The synthesis can be carried out in aqueous media at ambient conditions, does not require complicated setups, and the entire experimental procedure can be completed in less than an hour. Different organic acid combinations were tested, and it was found that the combination of ascorbic acid and oxalic acid can lead to the formation of hyperbranched Au nanocorals with distinct and extensive branching. Investigation of the formation mechanism revealed that the nanocorals are formed through a series of aggregation stages that begins with a one-dimensional (1D) assembly of branched Au nanoparticles, followed by aggregative growth into more expanded branched structures, which further merge to produce a densely packed three-dimensional (3D) network of nanocorals. The numerous tips and junctions in these hyperbranched nanocorals are plasmonic hot spots that allow for the SERS-based detection of rhodamine 6G, a toxic organic dye pollutant.

Molecular Modeling of Self-Assembling Peptides.

Peptide epitopes mediate as many as 40% of protein-protein interactions and fulfill signaling, inhibition, and activation roles within the cell. Beyond protein recognition, some peptides can self- or coassemble into stable hydrogels, making them a readily available source of biomaterials. While these 3D assemblies are routinely characterized at the fiber level, there are missing atomistic details about the assembly scaffold. Such atomistic detail can be useful in the rational design of more stable scaffold structures and with improved accessibility to functional motifs. Computational approaches can in principle reduce the experimental cost of such an endeavor by predicting the assembly scaffold and identifying novel sequences that adopt said structure. Yet, inaccuracies in physical models and inefficient sampling have limited atomistic studies to short (two or three amino acid) peptides. Given recent developments in machine learning and advances in sampling strategies, we revisit the suitability of physical models for this task. We use the MELD (Modeling Employing Limited Data) approach to drive self-assembly in combination with generic data in cases where conventional MD is unsuccessful. Finally, despite recent developments in machine learning algorithms for protein structure and sequence predictions, we find the algorithms are not yet suited for studying the assembly of short peptides.

Modeling the three-dimensional connectivity of in vitro cortical ensembles coupled to Micro-Electrode Arrays.

Nowadays, in vitro three-dimensional (3D) neuronal networks are becoming a consolidated experimental model to overcome most of the intrinsic limitations of bi-dimensional (2D) assemblies. In the 3D environment, experimental evidence revealed a wider repertoire of activity patterns, characterized by a modulation of the bursting features, than the one observed in 2D cultures. However, it is not totally clear and understood what pushes the neuronal networks towards different dynamical regimes. One possible explanation could be the underlying connectivity, which could involve a larger number of neurons in a 3D rather than a 2D space and could organize following well-defined topological schemes. Driven by experimental findings, achieved by recording 3D cortical networks organized in multi-layered structures coupled to Micro-Electrode Arrays (MEAs), in the present work we developed a large-scale computational network model made up of leaky integrate-and-fire (LIF) neurons to investigate possible structural configurations able to sustain the emerging patterns of electrophysiological activity. In particular, we investigated the role of the number of layers defining a 3D assembly and the spatial distribution of the connections within and among the layers. These configurations give rise to different patterns of activity that could be compared to the ones emerging from real in vitro 3D neuronal populations. Our results suggest that the introduction of three-dimensionality induced a global reduction in both firing and bursting rates with respect to 2D models. In addition, we found that there is a minimum number of layers necessary to obtain a change in the dynamics of the network. However, the effects produced by a 3D organization of the cells is somewhat mitigated if a scale-free connectivity is implemented in either one or all the layers of the network. Finally, the best matching of the experimental data is achieved supposing a 3D connectivity organized in structured bundles of links located in different areas of the 2D network.

A Practice-Oriented Proposal to Consider the Flange Effect in Equivalent Frame Modeling of Masonry Buildings

This paper focuses on the so-called “flange effect” in unreinforced masonry buildings when the connection among walls is good, thus forming a 3D assembly of intersecting piers (with L-, C-, T-, or I-shaped cross-sections). Given the direction of the horizontal seismic action, the presence of such flanges (the piers loaded out-of-plane) can influence the response of the in-plane loaded pier (the web) in terms of failure modes, maximum strength, and displacement capacity. Specific rules are proposed in codes to evaluate the effective width of the flange, for the in-plane verification of a single masonry wall. However, in the case of 3D equivalent frame (EF) modeling of the whole building, all the intersecting piers should be considered entirely, to model the response in both the orthogonal directions as well as the torsional behavior, but this may lead to overestimating the flange effect if a perfect connection is assumed. This paper investigates the capability of simulating the actual behavior in EF models by introducing an elastic shear connection at the intersection between two piers using an “equivalent beam”, coupling the nodes at the top of piers. A practice-oriented analytical formulation is proposed to calibrate such a flange effect on the basis of the geometric features and material properties of the web and the flange. Its reliability is tested at the scale of simple 3D assemblies and entire buildings as well. Finite element parametric analyses on masonry panels with symmetrical I- and T-shaped cross-sections have been performed to investigate the axial load redistribution between the flanges and the web and the consequent repercussion on the overall performance of the web. The results have proven that, after a calibration of the shear connection, the variation of axial force between the web and the flanges is correctly reproduced and the strength criteria for 2D panels provide reliable results. Finally, in the conclusions, some practical hints for simulating an imperfect wall-to-wall connection are also provided, since this case is relevant in historic masonry buildings, which are characterized by different masonry types, transformations over time, and already-cracked conditions.