Structural Insights into the Dynamic Assembly of a YFV sNS1 Tetramer.

Yellow fever virus (YFV) infections can cause severe diseases in humans, resulting in mass casualties in Africa and the Americas each year. Secretory NS1 (sNS1) is thought to be used as a diagnostic marker of flavivirus infections, playing an essential role in the flavivirus life cycle, but little is known about the composition and structure of YFV sNS1. Here, we present that the recombinant YFV sNS1 exists in a heterogeneous mixture of oligomerizations, predominantly in the tetrameric form. The cryoEM structures show that the YFV tetramer of sNS1 is stacked by the hydrophobic interaction between ß-roll domains and greasy fingers. According to the 3D variability analysis, the tetramer is in a semi-stable state that may contain multiple conformations with dynamic changes. We believe that our study provides critical insights into the oligomerization of NS1 and will aid the development of NS1-based diagnoses and therapies.

Light-Driven, Dynamic Assembly of Micron-To-Centimeter Parts, Micromachines and Microbot Swarms.

This work describes light-driven assembly of dynamic formations and functional particle swarms controlled by appropriately programmed light patterns. The system capitalizes on the use of a fluidic bed whose low thermal conductivity assures that light-generated heat remains "localized" and sets strong convective flows in the immediate vicinity of the particles being irradiated. In this way, even low-power laser light or light from a desktop slide projector can be used to organize dynamic formations of objects spanning four orders of magnitude in size (from microns to centimeters) and over nine orders of magnitude in terms of mass. These dynamic assemblies include open-lattice structures with individual particles performing intricate translational and/or rotational motions, density-gradient particle arrays, nested architectures of mechanical components (e.g., planetary gears), or swarms of light-actuated microbots controlling assembly of other objects.

The Microtubule End Binding Protein Mal3 Is Essential for the Dynamic Assembly of Microtubules during Magnaporthe oryzae Growth and Pathogenesis.

Cytoskeletal microtubules (MTs) play crucial roles in many aspects of life processes in eukaryotic organisms. They dynamically assemble physiologically important MT arrays under different cell conditions. Currently, aspects of MT assembly underlying the development and pathogenesis of the model plant pathogenic fungus Magnaporthe oryzae (M. oryzae) are unclear. In this study, we characterized the MT plus end binding protein MoMal3 in M. oryzae. We found that knockout of MoMal3 results in defects in hyphal polar growth, appressorium-mediated host penetration and nucleus division. Using high-resolution live-cell imaging, we further found that the MoMal3 mutant assembled a rigid MT in parallel with the MT during hyphal polar growth, the cage-like network in the appressorium and the stick-like spindle in nuclear division. These aberrant MT organization patterns in the MoMal3 mutant impaired actin-based cell growth and host infection. Taken together, these findings showed that M. oryzae relies on MoMal3 to assemble elaborate MT arrays for growth and infection. The results also revealed the assembly mode of MTs in M. oryzae, indicating that MTs are pivotal for M. oryzae growth and host infection and may be new targets for devastating fungus control.

Three Stages of Dynamic Assembly Process of Dipeptide-Based Supramolecular Gel Revealed by In Situ Infrared Spectroscopy.

The exploration of short peptide-based assembly is vital for understanding protein-misfolding-associated diseases and seeking strategies to attenuate aggregate formation. While, the molecular mechanism of their structural evolution remains poorly studied in view of the dynamic and unpredictable assembly process. Herein, infrared (IR) spectroscopy, which serves as an in situ and real-time analytical technique, was intelligently employed to investigate the mechanism of phase transition and aggregate formation during the dynamic assembly process of diphenylalanine. Combined with other spectroscopy and electron microscopy technologies, three stages of gel formation and the main driving forces in different stages were revealed. A variety of stoichiometric methods such as continuous wavelet transform, principal component analysis, and two-dimensional correlation spectroscopy techniques were conducted to analyze the original time-dependent IR spectra to obtain detailed information on the changes in the amide bands and hydration layer. The microenvironment of hydrogen bonding among amide bands was significantly changed with the addition of pyridine derivatives, resulting in great differences in the properties of co-assembled gels. This work not only provides a universal analytical way to reveal the dynamic assembly process of dipeptide-based supramolecular gel but also expands their applications in supramolecular regulation and high-throughput screens in situ.

A Smart DNA-Based Nanosystem Containing Ribosome-Regulating siRNA for Enhanced mRNA Transfection.

Messenger RNA (mRNA) transfection is the prerequisite for the application of mRNA-based therapeutics. In hard-to-transfect cells, such as macrophages, the effective transfection of mRNA remains a long-standing challenge. Herein, a smart DNA-based nanosystem is reported containing ribosome biogenesis-promoting siRNA, realizing efficient mRNA transfection in macrophages. Four monomers are copolymerized to form a nanoframework (NF), including N-isopropylacrylamide (NIPAM) as the skeleton and acrydite-DNA as the initiator to trigger the cascade assembly of DNA hairpins (H1-polyT and H2-siRNA). By virtue of the phase transition characteristic of polymeric NIPAM, below the lower critical solution temperature (LCST, ≈34 °C), the NF swells to expose polyT sequences to hybridize with the polyA tail of mRNA. Above the LCST, the NF deswells to encapsulate mRNA. The disulfide bond in the NF responds to glutathione, triggering the disassembly of the nanosystem; the siRNA and mRNA are released in response to triphosadenine and RNase H. The siRNA down-regulates the expression of heat shock protein 27, which up-regulates the expression of phosphorylated ribosomal protein S6. The nanosystem shows satisfactory mRNA transfection and translation efficiency in a mouse model. It is envisioned that the DNA-based nanosystem will provide a promising carrier to deliver mRNA in hard-to-transfect cells and promote the development of mRNA-based therapeutics.

Endogenous dual miRNA-triggered dynamic assembly of DNA nanostructures for in-situ dual siRNA delivery.

A theranostic strategy of multiple microRNA (miRNA)-triggered in-situ delivery of small interfering RNA (siRNA) can effectively improve the precise therapy of cancer cells. Benefiting from the advantages of programmability, specific molecular recognition, easy functionalization and marked biocompatibility of DNA nanostructures, we designed a three-dimensional (3D) DNA nano-therapeutic platform for dual miRNA-triggered in-situ delivery of siRNA. The 3D DNA nanostructure (TY1Y2) was constructed based on the self-assembly of a DNA tetrahedra scaffold, two sets of Y-shaped DNA (Y1 and Y2), and EpCAM-aptamer which functionalized as the ligand molecule for the recognition of specific cancer cells. After being specifically internalized into the targeted cancer cells, TY1Y2 was triggered by two endogenous miRNAs (miR-21 and miR-122), resulting in the generation of strong fluorescence resonance energy transfer fluorescent signal for dual miRNAs imaging. Meanwhile, the therapeutic siRNAs (siSurvivin and siBcl2) could also be in-situ generated and released from TY1Y2 through the strand-displacement reactions for the synergistic gene therapy of cancer cells. This 3D DNA nanostructure integrated the specific imaging of endogenous biomarkers and the in-situ delivery of therapeutic genes into the multifunctional nanoplatform, revealing the promising applications for the diagnosis and treatment of cancer. Electronic Supplementary Material: Supplementary material is available in the online version of this article at 10.1007/s40843-022-2420-y.

Structural studies of the nucleus-like assembly of jumbo bacteriophage 201φ2-1.

The jumbo phages encode proteins that assemble to form a nucleus-like compartment in infected cells. Here we report the cryo-EM structure and biochemistry characterization of gp105, a protein that is encoded by the jumbo phage 201φ2-1 and is involved in the formation of the nucleus-like compartment in phage 201φ2-1 infected Pseudomonas chlororaphis. We found that, although most gp105 molecules are in the monomeric state in solution, a small portion of gp105 assemble to form large sheet-like assemblies and small cube-like particles. Reconstruction of the cube-like particles showed that the particle consists of six flat head-to-tail tetramers arranged into an octahedral cube. The four molecules at the contact interface of two head-to-tail tetramers are 2-fold symmetry-related and constitute a concave tetramer. Further reconstructions without applying symmetry showed that molecules in the particles around the distal ends of a 3-fold axis are highly dynamic and have the tendency to open up the assembly. Local classifications and refinements of the concave tetramers in the cube-like particle resulted in a map of the concave tetramer at a resolution of 4.09 Å. Structural analysis of the concave tetramer indicates that the N and C terminal fragments of gp105 are important for mediating the intermolecular interactions, which was further confirmed by mutagenesis studies. Biochemistry assays showed that, in solution, the cube-like particles of gp105 are liable to either disassemble to form the monomers or recruit more molecules to form the high molecular weight lattice-like assembly. We also found that monomeric gp105s can self-assemble to form large sheet-like assemblies in vitro, and the assembly of gp105 in vitro is a reversible dynamic process and temperature-dependent. Taken together, our results revealed the dynamic assembly of gp105, which helps to understand the development and function of the nucleus-like compartment assembled by phage-encoded proteins.

Dynamic DNA Nanostructures for Cell Manipulation.

Dynamic DNA nanostructures are DNA nanostructures with reconfigurable elements that can undergo structural transformations in response to specific stimuli. Thus, anchoring dynamic DNA nanostructures on cell membranes is an attractive and promising strategy for well-controlled cell manipulation. Here, we review the latest progress in dynamic DNA nanostructures for cell manipulation. Commonly used mechanisms for dynamic DNA nanostructures are first introduced. Subsequently, we summarize the anchoring strategies for dynamic DNA nanostructures on cell membranes and list possible applications (including programming cell membrane receptors, controlling ligand activity and drug delivery, capturing and releasing cells, and assembling cells into clusters). Finally, insights into the remaining challenges are presented.

Lysosome Interference Enabled by Proton-Driven Dynamic Assembly of DNA Nanoframeworks inside Cells.

Coupling materials chemistry systems to biological processes is a promising way to rationally modulate lysosomal functions. A proton-driven dynamic assembly of a DNA nanoframework inside cells coupled with the lysosome-mediated endocytosis pathways/lysosomal maturation, gives the rational modulation of lysosomal functions, which we term "lysosome interference". Through lysosome-mediated endocytosis, the DNA nanoframework with acid-responsive semi-i-motif enters the lysosome and assembles into an aggregate in a process triggered by lysosomal acidity. The aggregate is suitable for long-term retention. The consumption of protons resulted in lysosomal acidity reduction and hydrolase activity attenuation, thus hindering the degradation of nucleic acid drugs in the lysosome and improving gene silencing effects. This study shows a new way to achieve lysosome interference by coupling the subcellular microenvironment with a precisely programmable assembly system.

Dispersing swimming microalgae in self-assembled nanocellulose suspension: Unveiling living colloid dynamics in cholesteric liquid crystals.

Active matter comprises individual energy-consuming components that convert locally stored energy into mechanical motion. Among these, liquid crystal dispersed self-propelled colloids have displayed fascinating dynamic effects and nonequilibrium behaviors. In this work, we introduce a new type of active soft matter based on swimming microalgae and lyotropic nanocellulose liquid crystal. Cellulose is a kind of biocompatible polysaccharide that nontoxic to living biological colloids. In contrast to microalgae locomotion in isotropic and low viscosity media, we demonstrate that the propulsion force of swimming microalgae can overcome the stabilizing elastic force in cholesteric nanocellulose liquid crystal, with the displacement dynamics (gait, direction, frequency, and speed) be altered by the surrounding medium. Simultaneously, the active stress and shear flow exerted by swimming microalgae can introduce local perturbation in surrounding liquid crystal orientation order. The latter effect yields hydrodynamic fluctuations in bulk phase as well as layer undulations, helicoidal axis splay deformation and director bending in the cholesteric assembly, which finally followed by a recovery according to the inherent viscoelasticity of liquid crystal matrix. Our results point to an unorthodox design concept to generate a new type of hybrid soft matter that combines nontoxic cholesteric liquid crystal and active particles, which are expected to open opportunities in biosensing and biomechanical applications.

Dynamic Transformation of DNA Nanostructures inside Living Cells.

DNA nanostructures, that show sequence programmable responsiveness to intracellular signals, have been explored as potential candidates of artificial dynamic functional structures in living cells. Recently, we developed a series of intracellular signals responding DNA nanostructures in living cells to perform a special mission. In this review, the developed DNA nanostructures and their dynamic transformation properties are summarized and discussed. The DNA nanostructures are generally categorized into DNA-inorganic nanomaterials and DNA-organic nanomaterials depending on the composition. At the end of this review, the challenges and prospects on instructing dynamic DNA nanostructures in living cells are discussed. We believe that this review will contribute to the further development of stimuli-responsive nanomaterials, which is of great potential in biomedical applications.

Ultrastretchable and Self-Healing Conductors with Double Dynamic Network for Omni-Healable Capacitive Strain Sensors.

Skin-mountable capacitive-type strain sensors with great linearity and low hysteresis provide inspiration for the interactions between human and machine. For practicality, high sensing performance, large stretchability, and self-healing are demanded but limited by stretchable electrode and dielectric and interfacial compatibility. Here, we demonstrate an extremely stretchable and self-healing conductor via both hard and soft tactics that combine conductive nanowire assemblies with double dynamic network based on π-π attractions and Ag-S coordination bonds. The obtained conductor outperforms the reported stretchable conductors by delivering an elongation of 3250%, resistance change of 223% at 2000% strain, high durability, and multiresponsive self-healability. Especially, this conductor accommodates large strain of 1500% at extremely knotted and twisted deformations. By sandwiching hydrogel conductors with a newly developed dielectric, ultrahigh stretchability and omni-healability are simultaneously achieved for the first time for a capacitive strain sensor inspired by metal-thiolate coordination chemistry, showing great potentials in wearable electronics and soft robotics.

Entropy Versus Enthalpy Controlled Temperature/Redox Dual-Triggered Cages for Selective Anion Encapsulation and Release.

New C3 -symmetric imidazole ligands were designed with phosphine and phosphine oxide linkers (LP and LPO , respectively) to demonstrate a dual-triggered dynamic closed coordination cage. Both LP and LPO form discrete Zn4 L4 -closed cages (1P and 1PO , respectively) with excellent selectively for BPh4 - , whereas 1P and 1PO encapsulate neither a slightly larger size anion [B(C6 H4 CH3 )4 - ] nor smaller size anions (BF4 - , PF6 - , SbF6 - , and OSO2 CF3 - ). 1PO exhibits more negative enthalpy and entropy changes upon anion encapsulation, thus releasing almost all of the encapsulated anions at high temperature (343 K) (trigger 1: BPh4 - ⊂1PO ← → 1PO +BPh4 - ). In contrast 1P has less negative enthalpy and entropy changes, thus preserving the captured anion over a wide range of temperatures (298 K to 343 K). The 1P cage can be quantitatively oxidized to the 1PO cage by a mild oxidant (Ox.=H2 O2 ), and therefore the captured anion can be released by a redox triggering event (trigger 2: BPh4 - ⊂1P +Ox.→1PO +BPh4 - ).

Controllable assembly of skeletal muscle-like bundles through 3D bioprinting.

3D printing is an effective technology for recreating skeletal muscle tissuein vitro. To achieve clinical skeletal muscle injury repair, relatively large volumes of highly aligned skeletal muscle cells are required; obtaining these is still a challenge. It is currently unclear how individual skeletal muscle cells and their neighbouring components co-ordinate to establish anisotropic architectures in highly homogeneous orientations. Here, we demonstrated a 3D printing strategy followed by sequential culture processes to engineer skeletal muscle tissue. The effects of confined printing on the skeletal muscle during maturation, which impacted the myotube alignment, myogenic gene expression, and mechanical forces, were observed. Our findings demonstrate the dynamic changes of skeletal muscle tissue duringin vitro3D construction and reveal the role of physical factors in the orientation and maturity of muscle fibres.

Understanding and Controlling the Crystallization Process in Reconfigurable Plasmonic Superlattices.

The crystallization of nanomaterials is a primary source of solid-state, photonic structures. Thus, a detailed understanding of this process is of paramount importance for the successful application of photonic nanomaterials in emerging optoelectronic technologies. While colloidal crystallization has been thoroughly studied, for example, with advanced in situ electron microscopy methods, the noncolloidal crystallization (freezing) of nanoparticles (NPs) remains so far unexplored. To fill this gap, in this work, we present proof-of-principle experiments decoding a crystallization of reconfigurable assemblies of NPs at a solid state. The chosen material corresponds to an excellent testing bed, as it enables both in situ and ex situ investigation using X-ray diffraction (XRD), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), atomic force microscopy (AFM), and optical spectroscopy in visible and ultraviolet range (UV-vis) techniques. In particular, ensemble measurements with small-angle XRD highlighted the dependence of the correlation length in the NPs assemblies on the number of heating/cooling cycles and the rate of cooling. Ex situ TEM imaging further supported these results by revealing a dependence of domain size and structure on the sample preparation route and by showing we can control the domain size over 2 orders of magnitude. The application of HAADF-STEM tomography, combined with in situ thermal control, provided three-dimensional single-particle level information on the positional order evolution within assemblies. This combination of real and reciprocal space provides insightful information on the anisotropic, reversibly reconfigurable assemblies of NPs. TEM measurements also highlighted the importance of interfaces in the polydomain structure of nanoparticle solids, allowing us to understand experimentally observed differences in UV-vis extinction spectra of the differently prepared crystallites. Overall, the obtained results show that the combination of in situ heating HAADF-STEM tomography with XRD and ex situ TEM techniques is a powerful approach to study nanoparticle freezing processes and to reveal the crucial impact of disorder in the solid-state aggregates of NPs on their plasmonic properties.

Dynamic emulsion droplets enabled by interfacial assembly of azobenzene-functionalized nanoparticles under light and magnetic field.

HYPOTHESIS: The ability to control the assembly of micro/nanosized particles at liquid-liquid interface with external inputs promises new opportunities in nanofabrication and biomedicines. This work aims to demonstrate a way to control of dynamic assembly of nanoparticles at liquid-liquid interface by light and magnetic field, which consequently enables the formation of dynamic emulsion droplets. EXPERIMENTS: Magnetic Fe3O4 nanoparticles functionalized with azobenzene moieties (Fe3O4@AZO) were synthesized and were dispersed in toluene/(N,N-dimethylformamide, DMF) binary solvent. After irradiation with UV or visible light, the assembly behavior of these Fe3O4 nanoparticles were evaluated by electron microscopy and fluorescent microscopy. FINDINGS: Under UV light, Fe3O4@AZO nanoparticles were self-assembled due to the increase of dipolar interaction from the photoisomerization of azobenzene and polar molecules, DMF, were harvested from a binary solvent of DMF/toluene. While under visible light, a relief of dipolar interactions between Fe3O4@AZO nanoparticles can induce the secondary assembly of these Fe3O4@AZO nanoparticles at DMF-toluene interface, resulting in DMF droplets covered by a layer of nanoparticle superlattices. More importantly, coupled with a magnetic field, these emulsion droplets can be shaped into one dimensional ones during the interfacial assembly process, thereby giving rise to dynamic emulsions controlled by light and magnetic field.

EBV-miR-BART12 accelerates migration and invasion in EBV-associated cancer cells by targeting tubulin polymerization-promoting protein 1.

Epstein-Barr virus (EBV) infection leads to cancers with an epithelial origin, such as nasopharyngeal cancer and gastric cancer, as well as multiple blood cell-based malignant tumors, such as lymphoma. Interestingly, EBV is also the first virus found to carry genes encoding miRNAs. EBV encodes 25 types of pre-miRNAs which are finally processed into 44 mature miRNAs. Most EBV-encoded miRNAs were found to be involved in the occurrence and development of EBV-related tumors. However, the function of EBV-miR-BART12 remains unclear. The findings of the current study revealed that EBV-miR-BART12 binds to the 3'UTR region of Tubulin Polymerization-Promoting Protein 1 (TPPP1) mRNA and downregulates TPPP1, thereby promoting the invasion and migration of EBV-related cancers, such as nasopharyngeal cancer and gastric cancer. The mechanism underlying this process was found to be the inhibition of TPPP1 by EBV-miRNA-BART12, which, in turn, inhibits the acetylation of α-tubulin, and promotes the dynamic assembly of microtubules, remodels the cytoskeleton, and enhances the acetylation of ß-catenin. ß-catenin activates epithelial to mesenchymal transition (EMT). These two processes synergistically promote the invasion and metastasis of tumor cells. To the best of our knowledge, this is the first study to reveal the role of EBV-miRNA-BART12 in the development of EBV-related tumors as well as the mechanism underlying this process, and suggests potential targets and strategies for the treatment of EBV-related tumors.

Precise Macroscopic Supramolecular Assemblies: Strategies and Applications.

Macroscopic supramolecular assembly (MSA) is a new concept in supramolecular science with a focus on interfacial assembly of macroscopic building blocks, which has largely extended the applicable materials of supramolecular assembly and provided new solutions to fabricating tissue scaffolds, soft devices, etc. The precision of the assembled structures is of great interest; unlike molecular assemblies, MSA precision is highly dependent on the matching degree of assembled surfaces because of the large interactive area and group number, which result in remarkably increased kinetic possibilities and metastable assemblies. This Concept introduces the principle, history, and development of MSA, elaborates the low-precision challenge in MSA, summarizes the strategies for precise MSA based on the different thermodynamic stability of precise/imprecise structures and control over assembly kinetics, and finally demonstrates the applications of precise MSA structures in advanced manufacture such as tissue scaffolds.

Dynamic Open Coordination Cage from Nonsymmetrical Imidazole-Pyridine Ditopic Ligands for Turn-On/Off Anion Binding.

This work demonstrates a new nonconventional ligand design, imidazole/pyridine-based nonsymmetrical ditopic ligands (1 and 1S ), to construct a dynamic open coordination cage from nonsymmetrical building blocks. Upon complex formation with Pd2+ at a 1:4 molar ratio, 1 and 1S initially form mononuclear PdL4 complexes (Pd2+ (1)4 and Pd2+ (1S )4 ) without formation of a cage. The PdL4 complexes undergo a stoichiometrically controlled structural transition to Pd2 L4 open cages ((Pd2+ )2 (1)4 and (Pd2+ )2 (1S )4 ) capable of anion binding, leading to turn-on anion binding. The structural transitions between the Pd2 L4 open cage and the PdL4 complex are reversible. Thus, stoichiometric addition (2 equiv) of free 1S to the (Pd2+ )2 (1S )4 open cage holding a guest anion ((Pd2+ )2 (1S )4 ⋅G- ) enables the structural transition to the Pd2+ (1S )4 complex, which does not have a cage and thus causes the release of the guest anion (Pd2+ (1S )4 +G- ).

Supramolecular Nanopumps with Chiral Recognition for Moving Organic Pollutants from Water.

Since organic pollutants in water resources have raised concerns on aquatic ecosystems and human health, mechanical machines such as a nanopump for rapid and efficient removal of pollutants from water with regeneration properties remains a challenge. Here, a pH-responsive artificial pump from left-handed porous tubules into right-handed solid fibers was presented by the self-assembly of bent-shaped aromatic amphiphiles. The bent-shaped amphiphile with a pH-sensitive segment was demonstrated in aromatic hexameric macrocycles, which could contract into dimeric disks. Such a switchable aromatic pore with superhydrophobicity was well-suited for an efficient removal and controlled release of organic pollutants from water through pulsating motion. The removal efficiency is found to be 78% for ethinyloestradiol and 82% for bisphenol. Additionally, the pumping accompanied by chiral inversion was endowed with a rapid removal and convenient regenerable ability. The inflation from right-handed solid fibers into left-handed tubules for efficient removal pollutants was remarkably promoted by (-)-acidic enantiomer of malic acid, whereas the contraction with full desorption of pollutants was incisively responsive to alkaline with (+)-conformation. The kinetically regulable porous device with a chiral recognition will provide a promising platform for the construction of rapid responsible machine for sewage treatment.