scholarly journals Coherent crystal branches: the impact of tetragonal symmetry on the 2D confined polymer nanostructure

IUCrJ ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 215-224
Author(s):  
Ziying Liang ◽  
Nan Zheng ◽  
Bo Ni ◽  
Ziwei Lai ◽  
Hui Niu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Helical Conformation ◽  
Tetragonal Symmetry ◽  
Polymer Crystals ◽  
Tetragonal Crystal ◽  
Tetragonal Crystals ◽  
Anisotropic Structures ◽  
The Impact ◽  
Tetragonal Cell ◽  
Coherent Crystal

The symmetry of polymer crystals greatly affects the optical, thermal conductivity and mechanical properties of the materials. Past studies have shown that the two-dimensional (2D) confined crystallization of polymer nanorods could produce anisotropic structures. However, few researchers have focused on understanding confined nanostructures from the perspective of crystal symmetry. In this research, we demonstrate the molecular chain self-assembly of tetragonal crystals under cylindrical confinement. We specifically selected poly(4-methyl-1-pentene) (P4MP1) with a 41 or 72 helical conformation (usually crystallizing with a tetragonal lattice) as the model polymer. We found a coherent crystal branching of the tetragonal crystal in the P4MP1 nanorods. The unusual 45°- and 135°-{200} diffractions and the meridional 220 diffraction (from 45°-tilted crystals) have shown a uniform crystal branching between the a 1-axis crystals and the 45°-tilted crystals in the rod long axis, which originates from a structural defect associated with tetragonal symmetry. Surprisingly, this chain packing defect in the tetragonal cell can be controlled to develop along the rod long axis in 2D confinement.

scholarly journals Virus-Like Particles Produced Using the Brome Mosaic Virus Recombinant Capsid Protein Expressed in a Bacterial System

2021 ◽  
Vol 22 (6) ◽  
pp. 3098
Author(s):  
Aleksander Strugała ◽  
Jakub Jagielski ◽  
Karol Kamel ◽  
Grzegorz Nowaczyk ◽  
Marcin Radom ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Mosaic Virus ◽  
Capsid Protein ◽  
Self Assembly ◽  
Environmental Changes ◽  
Expression System ◽  
Brome Mosaic Virus ◽  
Virus Like Particles ◽  
Assembly Principles ◽  
The Impact

Virus-like particles (VLPs), due to their nanoscale dimensions, presence of interior cavities, self-organization abilities and responsiveness to environmental changes, are of interest in the field of nanotechnology. Nevertheless, comprehensive knowledge of VLP self-assembly principles is incomplete. VLP formation is governed by two types of interactions: protein–cargo and protein–protein. These interactions can be modulated by the physicochemical properties of the surroundings. Here, we used brome mosaic virus (BMV) capsid protein produced in an E. coli expression system to study the impact of ionic strength, pH and encapsulated cargo on the assembly of VLPs and their features. We showed that empty VLP assembly strongly depends on pH whereas ionic strength of the buffer plays secondary but significant role. Comparison of VLPs containing tRNA and polystyrene sulfonic acid (PSS) revealed that the structured tRNA profoundly increases VLPs stability. We also designed and produced mutated BMV capsid proteins that formed VLPs showing altered diameters and stability compared to VLPs composed of unmodified proteins. We also observed that VLPs containing unstructured polyelectrolyte (PSS) adopt compact but not necessarily more stable structures. Thus, our methodology of VLP production allows for obtaining different VLP variants and their adjustment to the incorporated cargo.

scholarly journals Effects of Pathological Mutations on the Prion-Like Polymerisation of MyD88

2018 ◽  
Author(s):  
Ailís O’Carroll ◽  
Brieuc Chauvin ◽  
James Brown ◽  
Ava Meagher ◽  
Joanne Coyle ◽  
...  
Keyword(s):  
Single Molecule ◽  
Self Assembly ◽  
Point Mutations ◽  
Adaptor Protein ◽  
Full Length ◽  
Binary Response ◽  
Death Domain ◽  
Tir Domain ◽  
The Impact

AbstractA novel concept has emerged whereby the higher-order self-assembly of proteins provides a simple and robust mechanism for signal amplification. This appears to be a universal signalling mechanism within the innate immune system, where the recognition of pathogens or danger-associated molecular patterns need to trigger a strong, binary response within cells. Previously, multiple structural studies have been limited to single domains, expressed and assembled at high protein concentrations. We therefore set out to develop new in vitro strategies to characterise the behaviour of full-length proteins at physiological levels. In this study we focus on the adaptor protein MyD88, which contains two domains with different self-assembly properties: a TIR domain that can polymerise similarly to the TIR domain of Mal, and a Death Domain that has been shown to oligomerise with helical symmetry in the Myddosome complex. To visualize the behaviour of full-length MyD88 without purification steps, we use single-molecule fluorescence coupled to eukaryotic cell-free protein expression. These experiments demonstrate that at low protein concentration, only full-length MyD88 forms prion-like polymers. We also demonstrate that the metastability of MyD88 polymerisation creates the perfect binary response required in innate signalling: the system is silenced at normal concentrations but upstream signalling creates a “seed” that triggers polymerisation and amplification of the response. These findings pushed us to re-interpret the role of polymerisation in MyD88-related diseases and we studied the impact of disease-associated point mutations L93P, R196C and L252P/L265P at the molecular level. We discovered that all mutations completely block the ability of MyD88 to polymerise. We also confirm that L252P, a gain-of-function mutation, allows the MyD88 mutant to form extremely stable oligomers, even when expressed at low nanomolar concentrations. Thus, our results are consistent with and greatly add to the findings on the Myddosomes digital ‘all-or-none’ responses and the behaviour of the oncogenic mutation of MyD88.

scholarly journals Size-Dependent Thermo- and Photoresponsive Plasmonic Properties of Liquid Crystalline Gold Nanoparticles

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 875
Author(s):  
Aleksander Promiński ◽  
Ewelina Tomczyk ◽  
Mateusz Pawlak ◽  
Agnieszka Jędrych ◽  
Józef Mieczkowski ◽  
...  
Keyword(s):  
Size Distribution ◽  
Long Range ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
High Yield ◽  
Condensed State ◽  
Organic Shell ◽  
Yield Production ◽  
Shell Composition ◽  
The Impact

Achieving remotely controlled, reversibly reconfigurable assemblies of plasmonic nanoparticles is a prerequisite for the development of future photonic technologies. Here, we obtained a series of gold-nanoparticle-based materials which exhibit long-range order, and which are controlled with light or thermal stimuli. The influence of the metallic core size and organic shell composition on the switchability is considered, with emphasis on achieving light-responsive behavior at room temperature and high yield production of nanoparticles. The latter translates to a wide size distribution of metallic cores but does not prevent their assembly into various, switchable 3D and 2D long-range ordered structures. These results provide clear guidelines as to the impact of size, size distribution, and organic shell composition on self-assembly, thus enhancing the smart design process of multi-responsive nanomaterials in a condensed state, hardly attainable by other self-assembly methods which usually require solvents.

Automated self-assembly programming paradigm: The impact of network topology

2009 ◽  
Vol 24 (7) ◽  
pp. 793-817 ◽  
Author(s):  
Lin Li ◽  
Jonathan M Garibaldi ◽  
Natalio Krasnogor
Keyword(s):  
Network Topology ◽  
Self Assembly ◽  
Programming Paradigm ◽  
The Impact

Self-Assembly of Cellulose in Super-Cooled Ionic Liquid under the Impact of Decelerated Antisolvent Infusion: An Approach toward Anisotropic Gels and Aerogels

2018 ◽  
Vol 19 (11) ◽  
pp. 4411-4422 ◽  
Author(s):  
Sven F. Plappert ◽  
Jean-Marie Nedelec ◽  
Harald Rennhofer ◽  
Helga C. Lichtenegger ◽  
Sigrid Bernstorff ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Self Assembly ◽  
The Impact

Supramolecular self-assembly of three-dimensional polyaniline and polypyrrole crystals

2014 ◽  
Vol 50 (84) ◽  
pp. 12757-12760 ◽  
Author(s):  
Yulun Tao ◽  
Juchuan Li ◽  
Anjian Xie ◽  
Shikuo Li ◽  
Ping Chen ◽  
...  
Keyword(s):  
Self Assembly ◽  
Room Temperature ◽  
Conductive Polymer ◽  
Three Dimensional ◽  
Polymer Crystals ◽  
Solvent Environment

Supramolecular self-assembly of 3D conductive polymer crystals in a suitable solvent environment at room temperature.

scholarly journals Investigating crosstalk among PTMs provides novel insight into the structural basis underlying the differential effects of Nt17 PTMs on mutant Httex1 aggregation

2021 ◽  
Author(s):  
Anass Chiki ◽  
Zhidian Zhang ◽  
Kolla Rajasekhar ◽  
Luciano A. Abriata ◽  
Iman Rostami ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Dynamics Simulation ◽  
Helical Conformation ◽  
Structural Basis ◽  
Similar Distribution ◽  
Post Translational Modifications ◽  
Differential Effects ◽  
The Impact ◽  
Insight Into

AbstractPost-translational modifications (PTMs) within the first 17 amino acids (Nt17) of the Huntingtin protein (Htt) have been shown to inhibit the aggregation and attenuate the toxicity of mutant Htt proteins in vitro and in various models of Huntington’s disease. Our group’s previous studies suggested that the Nt17 PTM code is a combinatorial code that involves a complex interplay between different PTMs. Here, we expand on these studies by investigating the effect of methionine 8 oxidation (oxM8) and crosstalk between this PTM and either lysine 6 acetylation (AcK6) or threonine 3 phosphorylation (pT3) on the aggregation of mutant Httex1. We show that M8 oxidation delays but does not inhibit the aggregation and has no effect on the final morphologies of mutant Httex1 aggregates. This delay in aggregation kinetics could be attributed to the transient accumulation of oligomeric aggregates, which disappear upon the formation of Httex1 oxM8 fibrils. Interestingly, the presence of both oxM8 and AcK6 resulted in dramatic inhibition of Httex1 fibrillization, whereas the presence of oxM8 did not influence the aggregation inhibitory effect of pT3. To gain insight into the structural basis underlying these proteins’ aggregation properties, we investigated the impact of each PTM and the combination of these PTMs on the conformational properties of the Nt17 peptide by circular dichroism spectroscopy and molecular dynamics simulation. These studies show that M8 oxidation decreases the helicity of the Nt17 in the presence or absence of PTMs and provides novel insight into the structural basis underlying the effects of different PTMs on mutant Httex1 aggregation. PTMs that lower the mutant Httex1 aggregation rate (oxM8, AcK6/oxM8, pT3, pT3/oxM8, and phosphorylation at Serine 13) result in stabilization and increased population of a short N-terminal helix (first eight residues) in Nt17 or decreased abundance of other helical forms, including long helix and short C-terminal helix. PTMs that did not alter the aggregation of mutant Httex1 exhibit a similar distribution of helical conformation as the unmodified peptides. These results show that the relative abundance of N- vs. C-terminal helical conformations and long helices, rather than the overall helicity of Nt17, better explains the effect of different Nt17 PTMs on mutant Httex1; thus, explaining the lack of correlation between the effect of PTMs on the overall helicity of Nt17 and mutant Httex1 aggregation in vitro. Taken together, our results provide novel structural insight into the differential effects of single PTMs and crosstalk between different PTMs in regulating mutant Httex1 aggregation.TOC Figure

scholarly journals Self-sustained Marangoni Flows Driven by Chemical Reactions

2021 ◽  
Author(s):  
Anne-Déborah C. Nguindjel ◽  
Peter A. Korevaar
Keyword(s):  
Chemical Reactions ◽  
Self Assembly ◽  
Marangoni Flow ◽  
Chemical Systems ◽  
Fuel Delivery ◽  
Threshold Conditions ◽  
The Impact ◽  
Assembly Pathways ◽  
Equilibrium Chemical ◽  
Photoacid Generator

Out-of-equilibrium chemical systems, comprising reaction networks and molecular self-assembly pathways, rely on the delivery of reagents. Rather than via external flow, diffusion or convection, we aim at self-sustained reagent delivery. Therefore, we explore how the coupling of Marangoni flow with chemical reactions can generate self-sustained flows, driven by said chemical reactions, and – in turn – sustained by the delivery of reagents for this reaction. We combine a photoacid generator with a pH-responsive surfactant, such that local UV exposure decreases the pH, increases the surface tension and triggers the emergence of a Marangoni flow. We study the impact of reagent concentrations and identify threshold conditions at which flow can emerge. Surprisingly, we unraveled an antagonistic influence of the reagents on key features of the flow such as interfacial velocity and duration, and rationalize these findings via a kinetic model. Our study displays the potential of reaction-driven flow to establish autonomous control in fuel delivery of out-of-equilibrium systems.

scholarly journals Breath-Figures Self-Assembly, the Versatile Method of Manufacturing Membranes and Porous Structures: Physical, Chemical and Technological Aspects

2017 ◽  
Author(s):  
Edward Bormashenko
Keyword(s):  
Self Assembly ◽  
Interfacial Phenomena ◽  
Physical Parameters ◽  
Porous Structures ◽  
Temporal Scales ◽  
Breath Figures ◽  
Spatial And Temporal Scales ◽  
Multi Scale ◽  
Physical Chemical ◽  
The Impact

The review is devoted to the physical, chemical and technological aspects of the breath-figures self-assembly process. Main stages of the process and the impact of the polymer architecture and physical parameters of the breath-figures self-assembly on the eventual pattern are covered. The review is focused on the hierarchy of spatial and temporal scales inherent for the breath-figures self-assembly. Multi-scale patterns arising from the process are addressed. The characteristic spatial lateral scales of patterns vary from nanometers to dozens of micrometers. The temporal scales of the process span from micro-seconds to seconds. The qualitative analysis performed in the paper demonstrates that the process is mainly governed by the interfacial phenomena, whereas the impact of inertia and gravity is negligible. Characterization and applications of polymer films manufactured with breath-figures self-assembly are discussed.

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