scholarly journals Biocatalysis of d,l-Peptide Nanofibrillar Hydrogel

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 2995 ◽  
Author(s):  
Tiziano Carlomagno ◽  
Maria C. Cringoli ◽  
Slavko Kralj ◽  
Marina Kurbasic ◽  
Paolo Fornasiero ◽  
...  
Keyword(s):  
Self Assembly ◽  
Solid Phase ◽  
Building Blocks ◽  
Cd Spectroscopy ◽  
Tem Analysis ◽  
Design Rules ◽  
Self Assembling ◽  
Transmission Electron ◽  
Oscillatory Rheometry ◽  
The Many

Self-assembling peptides are attracting wide interest as biodegradable building blocks to achieve functional nanomaterials that do not persist in the environment. Amongst the many applications, biocatalysis is gaining momentum, although a clear structure-to-activity relationship is still lacking. This work applied emerging design rules to the heterochiral octapeptide sequence His–Leu–DLeu–Ile–His–Leu–DLeu–Ile for self-assembly into nanofibrils that, at higher concentration, give rise to a supramolecular hydrogel for the mimicry of esterase-like activity. The peptide was synthesized by solid-phase and purified by HPLC, while its identity was confirmed by 1H-NMR and electrospray ionization (ESI)-MS. The hydrogel formed by this peptide was studied with oscillatory rheometry, and the supramolecular behavior of the peptide was investigated with transmission electron microscopy (TEM) analysis, circular dichroism (CD) spectroscopy, thioflavin T amyloid fluorescence assay, and attenuated total reflectance (ATR) Fourier-transform infrared (FT-IR) spectroscopy. The biocatalytic activity was studied by monitoring the hydrolysis of p-nitrophenyl acetate (pNPA) at neutral pH, and the reaction kinetics followed an apparent Michaelis–Menten model, for which a Lineweaver–Burk plot was produced to determine its enzymatic parameters for a comparison with the literature. Finally, LC–MS analysis was conducted on a series of experiments to evaluate the extent of, if any, undesired peptide acetylation at the N-terminus. In conclusion, we provide new insights that allow gaining a clearer picture of self-assembling peptide design rules for biocatalysis.

scholarly journals Computationally designed peptides for self-assembly of nanostructured lattices

2016 ◽  
Vol 2 (9) ◽  
pp. e1600307 ◽  
Author(s):  
Huixi Violet Zhang ◽  
Frank Polzer ◽  
Michael J. Haider ◽  
Yu Tian ◽  
Jose A. Villegas ◽  
...  
Keyword(s):  
Self Assembly ◽  
Noncovalent Interactions ◽  
Building Blocks ◽  
Covalent Modification ◽  
Amino Acid Sequences ◽  
Peptide Sequence ◽  
Self Assembling ◽  
Transmission Electron ◽  
Wide Range ◽  
Micrometer Scale

Folded peptides present complex exterior surfaces specified by their amino acid sequences, and the control of these surfaces offers high-precision routes to self-assembling materials. The complexity of peptide structure and the subtlety of noncovalent interactions make the design of predetermined nanostructures difficult. Computational methods can facilitate this design and are used here to determine 29-residue peptides that form tetrahelical bundles that, in turn, serve as building blocks for lattice-forming materials. Four distinct assemblies were engineered. Peptide bundle exterior amino acids were designed in the context of three different interbundle lattices in addition to one design to produce bundles isolated in solution. Solution assembly produced three different types of lattice-forming materials that exhibited varying degrees of agreement with the chosen lattices used in the design of each sequence. Transmission electron microscopy revealed the nanostructure of the sheetlike nanomaterials. In contrast, the peptide sequence designed to form isolated, soluble, tetrameric bundles remained dispersed and did not form any higher-order assembled nanostructure. Small-angle neutron scattering confirmed the formation of soluble bundles with the designed size. In the lattice-forming nanostructures, the solution assembly process is robust with respect to variation of solution conditions (pH and temperature) and covalent modification of the computationally designed peptides. Solution conditions can be used to control micrometer-scale morphology of the assemblies. The findings illustrate that, with careful control of molecular structure and solution conditions, a single peptide motif can be versatile enough to yield a wide range of self-assembled lattice morphologies across many length scales (1 to 1000 nm).

scholarly journals Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

2018 ◽  
Vol 14 ◽  
pp. 1704-1722 ◽  
Author(s):  
Cristina Morar ◽  
Pedro Lameiras ◽  
Attila Bende ◽  
Gabriel Katona ◽  
Emese Gál ◽  
...  
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
Tem Analysis ◽  
Design Synthesis ◽  
Perylene Bisimide ◽  
Self Assembling ◽  
Chemoselective Synthesis ◽  
Azobenzene Mesogens ◽  
Vt Nmr ◽  
Peripheral Unit

Background: 4-(n-Octyloxy)aniline is a known component in the elaboration of organic materials with mesogenic properties such as N-substituted Schiff bases, perylene bisimide assemblies with a number of 2-amino-4,6-bis[4-(n-octyloxy)phenylamino]-s-triazines, amphiphilic azobenzene-containing linear-dendritic block copolymers and G-0 monomeric or dimeric dendritic liquid crystals with photochromic azobenzene mesogens. The present ab initio study explores a previously unknown use of 4-(n-octyloxy)aniline in the synthesis, structure and supramolecular behaviour of new dendritic melamines. Results: Starting from 4-(n-octyloxy)aniline, seven G-2 melamine-based dendrimers were obtained in 29–79% overall yields. Their iterative convergent- and chemoselective synthesis consisted of SN2-Ar aminations of cyanuric chloride and final triple N-acylations and Williamson etherifications (→ G-2 covalent trimers) or stoichiometric carboxyl/amino 1:3 neutralisations (→ G-2 ionic trimers). These transformations connected G-1 chloro- and amino-termini dendrons to m-trivalent cores (triazin-2,4,6-triyl and benzene-1,3,5-triyl units) or tripodands (central building blocks), such as N-substituted melamines with 4-hydroxyphenyl or phenyl-4-oxyalkanoic motifs. Owing to the diversity of cores and central building blocks, the structural assortment of the dendritic series was disclosed by solvation effects (affecting reactivity), rotational stereodynamism and self-organisation phenomena (determining a vaulted and/or propeller macromolecular shape in solution). DFT calculations (in solution), (VT) NMR and IR (KBr) spectroscopy supported these assignments. TEM analysis revealed the ability of the title compounds towards self-assembling into homogeneously packed spherical nano-aggregates. Conclusions: The (non)covalent synthesis and step-by-step structural elucidation of novel G-2 melamine dendrimers based on 4-(n-octyloxy)aniline are reported. Our study demonstrates the crucial influence of the nature (covalent vs ionic) of the dendritic construction in tandem with that of its central building blocks on the aptitude of dendrimers to self-organise in solution and to self-assembly in the solid state.

Factors Affecting Molecular Self-Assembly and Its Mechanism

2012 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Hueyling Tan
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
Molecular Engineering ◽  
Molecular Structures ◽  
Polymer Science ◽  
New Approach ◽  
Factors Affecting ◽  
Dna Structures ◽  
Self Assembling ◽  
Wide Range

Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use ofpeptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study ofbiological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries ofexisting disciplines. Many self-assembling systems are rangefrom bi- andtri-block copolymers to DNA structures as well as simple and complex proteins andpeptides. The ultimate goal is to harness molecular self-assembly such that design andcontrol ofbottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes oflife and non-life science applications. Such aspirations can be achievedthrough understanding thefundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.

Growth of Epitaxial IrSi3 Layers on Si(111)

1989 ◽  
Vol 160 ◽  
Author(s):  
T. L. Lin ◽  
C. W. Nieh
Keyword(s):  
Surface Morphology ◽  
Molecular Beam ◽  
Solid Phase ◽  
Single Mode ◽  
Growth Conditions ◽  
Tem Analysis ◽  
Mbe Growth ◽  
Good Surface ◽  
Transmission Electron

AbstractEpitaxial IrSi3 films have been grown on Si (111) by molecular beam epitaxy (MBE) at temperatures ranging from 630 to 800 °C and by solid phase epitaxy (SPE) at 500 °C. Good surface morphology was observed for IrSi3 layers grown by MBE at temperatures below 680 °C, and an increasing tendency to form islands is noted in samples grown at higher temperatures. Transmission electron microscopy (TEM) analysis reveals that the IrSi3 layers grow epitaxially on Si(111) with three epitaxial modes depending on the growth conditions. For IrSi3 layers grown by MBE at 630 °C, two epitaxial modes were observed with ~ 50% area coverage for each mode. Single mode epitaxial growth was achieved at a higher MBE growth temperature, but with island formation in the IrSi3 layer. A template technique was used with MBE to improve the IrSi3 surface morphology at higher growth temperatures. Furthermore, single-crystal IrSi3 was grown on Si(111) at 500 °C by SPE, with annealing performed in-situ in a TEM chamber.

scholarly journals Synthesis and Self-assembly of Amphiphilic Precision Glycomacromolecules

2021 ◽  
Author(s):  
Alexander Banger ◽  
Julian Sindram ◽  
Marius Otten ◽  
Jessica Kania ◽  
Alexander Strzelczyk ◽  
...  
Keyword(s):  
Self Assembly ◽  
Solid Phase ◽  
Building Blocks ◽  
Polymer Synthesis

We present the synthesis of so called amphiphilic glycomacromolecules (APGs) by using solid-phase polymer synthesis. Based on tailor made building blocks, monosdisperse APGs with varying compositions are synthesized, introducing carbohydrate...

Self Assembling Nanostructured Delivery Vehicles for Biochemically Reactive Pairs

1994 ◽  
Vol 351 ◽  
Author(s):  
Nir Kossovsky ◽  
A. Gelman ◽  
H.J. Hnatyszyn ◽  
E. Sponsler ◽  
G.-M. Chow
Keyword(s):  
Physical Properties ◽  
Self Assembly ◽  
Materials Science ◽  
Technology Development ◽  
Biological Behavior ◽  
X Ray Diffraction ◽  
Self Assembling ◽  
Transmission Electron ◽  
Carbon Ceramic

ABSTRACTIntrigued by the deceptive simplicity and beauty of macromolecular self-assembly, our laboratory began studying models of self-assembly using solids, glasses, and colloidal substrates. These studies have defined a fundamental new colloidal material for supporting members of a biochemically reactive pair.The technology, a molecular transportation assembly, is based on preformed carbon ceramic nanoparticles and self assembled calcium-phosphate dihydrate particles to which glassy carbohydrates are then applied as a nanometer thick surface coating. This carbohydrate coated core functions as a dehydroprotectant and stabilizes surface immobilized members of a biochemically reactive pair. The final product, therefore, consists of three layers. The core is comprised of the ceramic, the second layer is the dehydroprotectant carbohydrate adhesive, and the surface layer is the biochemically reactive molecule for which delivery is desired.We have characterized many of the physical properties of this system and have evaluated the utility of this delivery technology in vitro and in animal models. Physical characterization has included standard and high resolution transmission electron microscopy, electron and x-ray diffraction and ζ potential analysis. Functional assays of the ability of the system to act as a nanoscale dehydroprotecting delivery vehicle have been performed on viral antigens, hemoglobin, and insulin. By all measures at present, the favorable physical properties and biological behavior of the molecular transportation assembly point to an exciting new interdisciplinary area of technology development in materials science, chemistry and biology.

Cryogenic Transmission Electron Microscopy: Aqueous Suspensions of Nanoscale Objects

2013 ◽  
Vol 19 (6) ◽  
pp. 1542-1553 ◽  
Author(s):  
Nathan D. Burrows ◽  
R. Lee Penn
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Self Assembly ◽  
Aqueous Samples ◽  
Liquid Media ◽  
Cryogenic Transmission Electron Microscopy ◽  
Transmission Electron ◽  
The Many

AbstractDirect imaging of nanoscale objects suspended in liquid media can be accomplished using cryogenic transmission electron microscopy (cryo-TEM). Cryo-TEM has been used with particular success in microbiology and other biological fields. Samples are prepared by plunging a thin film of sample into an appropriate cryogen, which essentially produces a snapshot of the suspended objects in their liquid medium. With successful sample preparation, cryo-TEM images can facilitate elucidation of aggregation and self-assembly, as well as provide detailed information about cells and viruses. This work provides an explanation of sample preparation, detailed examples of the many artifacts found in cryo-TEM of aqueous samples, and other key considerations for successful cryo-TEM imaging.

scholarly journals Classification of self-assembling protein nanoparticle architectures for applications in vaccine design

2017 ◽  
Vol 4 (4) ◽  
pp. 161092 ◽  
Author(s):  
G. Indelicato ◽  
P. Burkhard ◽  
R. Twarock
Keyword(s):  
Self Assembly ◽  
Vaccine Design ◽  
Building Blocks ◽  
Coiled Coils ◽  
Specific Class ◽  
Regular Graphs ◽  
Humoral Immune ◽  
Self Assembling ◽  
Display Systems

We introduce here a mathematical procedure for the structural classification of a specific class of self-assembling protein nanoparticles (SAPNs) that are used as a platform for repetitive antigen display systems. These SAPNs have distinctive geometries as a consequence of the fact that their peptide building blocks are formed from two linked coiled coils that are designed to assemble into trimeric and pentameric clusters. This allows a mathematical description of particle architectures in terms of bipartite (3,5)-regular graphs. Exploiting the relation with fullerene graphs, we provide a complete atlas of SAPN morphologies. The classification enables a detailed understanding of the spectrum of possible particle geometries that can arise in the self-assembly process. Moreover, it provides a toolkit for a systematic exploitation of SAPNs in bioengineering in the context of vaccine design, predicting the density of B-cell epitopes on the SAPN surface, which is critical for a strong humoral immune response.

scholarly journals Free-standing supramolecular hydrogel objects by reaction-diffusion

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Matija Lovrak ◽  
Wouter E. J. Hendriksen ◽  
Chandan Maity ◽  
Serhii Mytnyk ◽  
Volkert van Steijn ◽  
...  
Keyword(s):  
Structure Formation ◽  
Self Assembly ◽  
Reaction Diffusion ◽  
Building Blocks ◽  
Assembly Process ◽  
Supramolecular Hydrogel ◽  
Free Standing ◽  
Spatial Control ◽  
Self Assembling ◽  
Vast Range

Abstract Self-assembly provides access to a variety of molecular materials, yet spatial control over structure formation remains difficult to achieve. Here we show how reaction–diffusion (RD) can be coupled to a molecular self-assembly process to generate macroscopic free-standing objects with control over shape, size, and functionality. In RD, two or more reactants diffuse from different positions to give rise to spatially defined structures on reaction. We demonstrate that RD can be used to locally control formation and self-assembly of hydrazone molecular gelators from their non-assembling precursors, leading to soft, free-standing hydrogel objects with sizes ranging from several hundred micrometres up to centimeters. Different chemical functionalities and gradients can easily be integrated in the hydrogel objects by using different reactants. Our methodology, together with the vast range of organic reactions and self-assembling building blocks, provides a general approach towards the programmed fabrication of soft microscale objects with controlled functionality and shape.

Peptide α-helices for synthetic nanostructures

2007 ◽  
Vol 35 (3) ◽  
pp. 487-491 ◽  
Author(s):  
M.G. Ryadnov
Keyword(s):  
Self Assembly ◽  
De Novo ◽  
Three Dimensional ◽  
Functional Materials ◽  
Protein Assemblies ◽  
Helical Peptides ◽  
Design Rules ◽  
Natural Protein ◽  
Self Assembling ◽  
Recent Developments

Supramolecular structures arising from a broad range of chemical archetypes are of great technological promise. Defining such structures at the nanoscale is crucial to access principally new types of functional materials for applications in bionanotechnology. In this vein, biomolecular self-assembly has emerged as an efficient approach for building synthetic nanostructures from the bottom up. The approach predominantly employs the spontaneous folding of biopolymers to monodisperse three-dimensional shapes that assemble into hierarchically defined mesoscale composites. An immediate interest here is the extraction of reliable rules that link the chemistry of biopolymers to the mechanisms of their assembly. Once established these can be further harnessed in designing supramolecular objects de novo. Different biopolymer classes compile a rich repertoire of assembly motifs to facilitate the synthesis of otherwise inaccessible nanostructures. Among those are peptide α-helices, ubiquitous folding elements of natural protein assemblies. These are particularly appealing candidates for prescriptive supramolecular engineering, as their well-established and conservative design rules give unmatched predictability and rationale. Recent developments of self-assembling systems based on helical peptides, including fibrous systems, nanoscale linkers and reactors will be highlighted herein.

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