scholarly journals Engineering Peptide-Based Polyelectrolyte Complexes with Increased Hydrophobicity

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 868 ◽  
Author(s):  
Sara Tabandeh ◽  
Lorraine Leon
Keyword(s):  
Charge Density ◽  
Self Assembly ◽  
Rational Design ◽  
Hydrophobicity Index ◽  
Polyelectrolyte Complexes ◽  
Polyelectrolyte Complexation ◽  
Future Work ◽  
Oppositely Charged ◽  
H And F Nmr

Polyelectrolyte complexation is a versatile platform for the design of self-assembled materials. Here we use rational design to create ionic hydrophobically-patterned peptides that allow us to precisely explore the role of hydrophobicity on electrostatic self-assembly. Polycations and polyanions were designed and synthesized with an alternating sequence of d- and l-chiral patterns of lysine or glutamic acid with either glycine, alanine or leucine due to their increasing hydrophobicity index, respectively. Two motifs were considered for the oppositely charged patterned peptides; one with equal residues of charged and uncharged amino acids and the other with increased charge density. Mass spectroscopy, circular dichroism, H- and F-NMR spectroscopy were used to characterize the polypeptides. Polyelectrolyte complexes (PECs) formed using the sequences were characterized using turbidity measurements, optical microscopy and infrared spectroscopy. Our results show that the critical salt concentration, a key measure of PEC stability, increased with both increasing charge density as well as hydrophobicity. Furthermore, by increasing the hydrophobicity, the amount of PEC formed increased with temperature, contrary to purely ionic PECs. Lastly, we assessed the encapsulation behavior of these materials using a hydrophobic dye. Concluding that encapsulation efficiency increased with hydrophobic content of the complexes providing insight for future work on the application of these materials for drug delivery.

scholarly journals Polyelectrolyte Complexation of Oligonucleotides by Charged Hydrophobic—Neutral Hydrophilic Block Copolymers

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 83 ◽  
Author(s):  
Alexander E. Marras ◽  
Jeffrey R. Vieregg ◽  
Jeffrey M. Ting ◽  
Jack D. Rubien ◽  
Matthew V. Tirrell
Keyword(s):  
Charge Density ◽  
Self Assembly ◽  
Block Size ◽  
Structure Property ◽  
Shell Nanoparticles ◽  
Polyelectrolyte Complexes ◽  
Structure Property Relationships ◽  
Polyelectrolyte Complexation ◽  
The Rich ◽  
Core Shell Nanoparticles

Polyelectrolyte complex micelles (PCMs, core-shell nanoparticles formed by complexation of a polyelectrolyte with a polyelectrolyte-hydrophilic neutral block copolymer) offer a solution to the critical problem of delivering therapeutic nucleic acids, Despite this, few systematic studies have been conducted on how parameters such as polycation charge density, hydrophobicity, and choice of charged group influence PCM properties, despite evidence that these strongly influence the complexation behavior of polyelectrolyte homopolymers. In this article, we report a comparison of oligonucleotide PCMs and polyelectrolyte complexes formed by poly(lysine) and poly((vinylbenzyl) trimethylammonium) (PVBTMA), a styrenic polycation with comparatively higher charge density, increased hydrophobicity, and a permanent positive charge. All of these differences have been individually suggested to provide increased complex stability, but we find that PVBTMA in fact complexes oligonucleotides more weakly than does poly(lysine), as measured by stability versus added salt. Using small angle X-ray scattering and electron microscopy, we find that PCMs formed from both cationic blocks exhibit very similar structure-property relationships, with PCM radius determined by the cationic block size and shape controlled by the hybridization state of the oligonucleotides. These observations narrow the design space for optimizing therapeutic PCMs and provide new insights into the rich polymer physics of polyelectrolyte self-assembly.

scholarly journals Deciphering the Role of π-Interactions in Polyelectrolyte Complexes Using Rationally Designed Peptides

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2074
Author(s):  
Sara Tabandeh ◽  
Cristina Elisabeth Lemus ◽  
Lorraine Leon
Keyword(s):  
Hydrogen Bonding ◽  
Phase Separation ◽  
Liquid Phase ◽  
Charge Density ◽  
Secondary Structures ◽  
Liquid Phase Separation ◽  
Polyelectrolyte Complexes ◽  
Π Interactions ◽  
Liquid Liquid Phase Separation

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

Self-assembly of oppositely charged particles in dilute ceramic suspensions: predictive role of simulations

Soft Matter ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 370-382 ◽  
Author(s):  
M. Cerbelaud ◽  
A. Videcoq ◽  
P. Abélard ◽  
C. Pagnoux ◽  
F. Rossignol ◽  
...  
Keyword(s):  
Self Assembly ◽  
Charged Particles ◽  
Predictive Role ◽  
Ceramic Suspensions ◽  
Oppositely Charged

scholarly journals Multiscale Molecular Modelling of ATP-fueled Supramolecular Polymerisation and Depolymerisation

2020 ◽  
Author(s):  
Claudio Perego ◽  
Luca Pesce ◽  
Riccardo Capelli ◽  
Subi J. George ◽  
Giovanni M. Pavan
Keyword(s):  
Molecular Modelling ◽  
Self Assembly ◽  
Rational Design ◽  
Atp Hydrolysis ◽  
Grand Challenge ◽  
Molecular Systems ◽  
Artificial Materials ◽  
Profound Knowledge ◽  
General Aspects

Fuel-regulated self-assembly is a key principle by which Nature creates spatiotemporally controlled materials and dynamic molecular systems that are in continuous communication (molecular exchange) with the external environment. Designing artificial materials that self-assemble and disassemble via conversion/consumption of a chemical fuel is a grand challenge in supramolecular chemistry, which requires a profound knowledge of the factors governing these complex systems. Here we focus on recently reported metal-coordinated monomers that polymerise in the presence of ATP and depolymerise upon ATP hydrolysis, exploring their fuel-regulated self-assembly/disassembly via multiscale molecular modelling. We use all-atom simulations to assess the role of ATP in stabilising these monomers in assemblies, and we then build on a minimalistic model to investigate their fuel-driven polymerization and depolymerization on a higher scale. In this way, we elucidate general aspects of fuel-regulated self-assembly that are important toward the rational design of new types of bioinspired materials.

scholarly journals Geometrical frustration as a potential design principle for peptide-based assemblies

2017 ◽  
Vol 7 (6) ◽  
pp. 20160141 ◽  
Author(s):  
Tao Jiang ◽  
Elizabeth L. Magnotti ◽  
Vincent P. Conticello
Keyword(s):  
Self Assembly ◽  
Rational Design ◽  
Structural Parameters ◽  
Two Dimensional ◽  
Protein Assemblies ◽  
Geometrical Frustration ◽  
Protein Motifs ◽  
Planar Shapes ◽  
And Function

Two-dimensional peptide and protein assemblies have been the focus of increased scientific research as they display significant potential for the creation of functional nanomaterials. Soluble subunits derived from a variety of protein motifs have been demonstrated to self-assemble into structurally defined nanosheets under environmentally benign conditions in which the components often retain their native structure and function. These types of two-dimensional assemblies may have an advantage for nanofabrication in that their extended planar shapes can be more straightforwardly incorporated into the current formats of nanoscale devices. However, significant challenges remain in the fabrication of these materials, particularly in devising methods to control the size, shape and internal structure of the resultant materials. Geometrical frustration may be envisioned as a possible mechanism to exert control over these structural parameters through rational design. While this objective has yet to be realized in practice, we discuss in this article the potential role of geometrical frustration as a principle to rationalize unusual self-assembly behaviour in several examples of two-dimensional peptide assemblies.

scholarly journals Multiscale Molecular Modelling of ATP-fueled Supramolecular Polymerisation and Depolymerisation

2020 ◽  
Author(s):  
Claudio Perego ◽  
Luca Pesce ◽  
Riccardo Capelli ◽  
Subi J. George ◽  
Giovanni M. Pavan
Keyword(s):  
Molecular Modelling ◽  
Self Assembly ◽  
Rational Design ◽  
Atp Hydrolysis ◽  
Grand Challenge ◽  
Molecular Systems ◽  
Artificial Materials ◽  
Profound Knowledge ◽  
General Aspects

Fuel-regulated self-assembly is a key principle by which Nature creates spatiotemporally controlled materials and dynamic molecular systems that are in continuous communication (molecular exchange) with the external environment. Designing artificial materials that self-assemble and disassemble via conversion/consumption of a chemical fuel is a grand challenge in supramolecular chemistry, which requires a profound knowledge of the factors governing these complex systems. Here we focus on recently reported metal-coordinated monomers that polymerise in the presence of ATP and depolymerise upon ATP hydrolysis, exploring their fuel-regulated self-assembly/disassembly via multiscale molecular modelling. We use all-atom simulations to assess the role of ATP in stabilising these monomers in assemblies, and we then build on a minimalistic model to investigate their fuel-driven polymerization and depolymerization on a higher scale. In this way, we elucidate general aspects of fuel-regulated self-assembly that are important toward the rational design of new types of bioinspired materials.

Quenching of fully symmetric mixtures of oppositely charged microgels: the role of soft stiffness

Soft Matter ◽  
2018 ◽  
Vol 14 (24) ◽  
pp. 5106-5120 ◽  
Author(s):  
Thiago Colla ◽  
Ronald Blaak ◽  
Christos N. Likos
Keyword(s):  
Molecular Dynamics ◽  
Binary System ◽  
Molecular Dynamics Simulations ◽  
Self Assembly ◽  
The Self ◽  
Coarse Grained ◽  
Dynamics Simulations ◽  
Oppositely Charged

Using molecular dynamics simulations, we investigate the self-assembly of a coarse-grained binary system of oppositely charged microgels, symmetric in size and concentration.

Effect of High Salt Concentration on Ion Clustering and Transport in Polymer Solid Electrolytes: a Molecular Dynamics Study of PEO-LiTFSI

2018 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky
Keyword(s):  
Polymer Electrolyte ◽  
Salt Concentration ◽  
Rational Design ◽  
Material System ◽  
Ion Dynamics ◽  
High Concentration ◽  
Anion Clusters ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

<div> <div> <div> <p>The model and analysis methods developed in this work are generally applicable to any polymer electrolyte/cation-anion combination, but we focus on the currently most prominent polymer electrolyte material system: poly(ethylene) oxide/Li- bis(trifluoromethane) sulfonamide (PEO + LiTFSI). The obtained results are surprising and challenge the conventional understanding of ionic transport in polymer electrolytes: the investigation of a technologically relevant salt concentration range (1 - 4 M) revealed the central role of the anion in coordinating and hindering Li ion movement. Our results provide insights into correlated ion dynamics, at the same time enabling rational design of better PEO-based electrolytes. In particular, we report the following novel observations. 1. Strong binding of the Li cation with the polymer competes with significant correlation of the cation with the salt anion. 2. The appearance of cation-anion clusters, especially at high concentration. 3. The asymmetry in the composition (and therefore charge) of such clusters; specifically, we find the tendency for clusters to have a higher number of anions than cations.</p> </div> </div> </div>

Effect of High Salt Concentration on Ion Clustering and Transport in Polymer Solid Electrolytes: a Molecular Dynamics Study of PEO-LiTFSI

2018 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky
Keyword(s):  
Polymer Electrolyte ◽  
Salt Concentration ◽  
Rational Design ◽  
Material System ◽  
Ion Dynamics ◽  
High Concentration ◽  
Anion Clusters ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

<div> <div> <div> <p>The model and analysis methods developed in this work are generally applicable to any polymer electrolyte/cation-anion combination, but we focus on the currently most prominent polymer electrolyte material system: poly(ethylene) oxide/Li- bis(trifluoromethane) sulfonamide (PEO + LiTFSI). The obtained results are surprising and challenge the conventional understanding of ionic transport in polymer electrolytes: the investigation of a technologically relevant salt concentration range (1 - 4 M) revealed the central role of the anion in coordinating and hindering Li ion movement. Our results provide insights into correlated ion dynamics, at the same time enabling rational design of better PEO-based electrolytes. In particular, we report the following novel observations. 1. Strong binding of the Li cation with the polymer competes with significant correlation of the cation with the salt anion. 2. The appearance of cation-anion clusters, especially at high concentration. 3. The asymmetry in the composition (and therefore charge) of such clusters; specifically, we find the tendency for clusters to have a higher number of anions than cations.</p> </div> </div> </div>

Directive Effect of Chain Length in Modulating Peptide Nano-assemblies

2020 ◽  
Vol 27 (9) ◽  
pp. 923-929
Author(s):  
Gaurav Pandey ◽  
Prem Prakash Das ◽  
Vibin Ramakrishnan
Keyword(s):  
Electron Microscopy ◽  
Amino Acids ◽  
Light Scattering ◽  
Chain Length ◽  
Self Assembly ◽  
The Self ◽  
Ionic Charge ◽  
Self Assembling ◽  
Biophysical Techniques

Background: RADA-4 (Ac-RADARADARADARADA-NH2) is the most extensively studied and marketed self-assembling peptide, forming hydrogel, used to create defined threedimensional microenvironments for cell culture applications. Objectives: In this work, we use various biophysical techniques to investigate the length dependency of RADA aggregation and assembly. Methods: We synthesized a series of RADA-N peptides, N ranging from 1 to 4, resulting in four peptides having 4, 8, 12, and 16 amino acids in their sequence. Through a combination of various biophysical methods including thioflavin T fluorescence assay, static right angle light scattering assay, Dynamic Light Scattering (DLS), electron microscopy, CD, and IR spectroscopy, we have examined the role of chain-length on the self-assembly of RADA peptide. Results: Our observations show that the aggregation of ionic, charge-complementary RADA motifcontaining peptides is length-dependent, with N less than 3 are not forming spontaneous selfassemblies. Conclusion: The six biophysical experiments discussed in this paper validate the significance of chain-length on the epitaxial growth of RADA peptide self-assembly.

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