Influence of Conventional Surfactants on the Self-Assembly of a Bola Type Amphiphilic Peptide

Mechanisms and influencing factors of peptide hydrogel formation and biomedicine applications of hydrogels

Self-assembled peptide-based hydrogels have shown great potential in bio-related applications due to their porous structure, strong mechanical stability, high biocompatibility, and easy functionalization. Herein, the structure and characteristics of hydrogels and the mechanism of action of several regular secondary structures during gelation are investigated. The factors influencing the formation of peptide hydrogels, especially the pH responsiveness and salt ion induction are analyzed and summarized. Finally, the biomedical applications of peptide hydrogels, such as bone tissue engineering, cell culture, antigen presentation, antibacterial materials, and drug delivery are reviewed.

Polar Zipper on a Peptide Nanomembrane: A Characterization by Potential of Mean Force

In this work, nanomembranes formed by the I₃XGK (X = Q, S, or N) polar peptides are studied to characterize the average force and energy required to separate two neighboring β-sheets laterally joined by polar zippers. The results presented are obtained using a methodology (state of the art) involving the pulling umbrella method to generate the samples (umbrella sampling) and the potential of mean force (PMF) to evaluate the energetic variation evolved in the process of separating the polar zipper. It was observed that the maximum force required to separate the regions linked by polar zippers is 1.48 kJ/mol nm for the I₃NGK nanomembrane and 1.22 kJ/mol nm [1.30 kJ/mol nm] for the I₃QGK [I₃SGK] nanomembranes, emphasizing that polar zippers play an important role in the interaction that interconnects β-sheets in broad and robust two-dimensional structures (tapes and membranes), offering an agile route to the construction of distinct nanomaterials from β-sheets. Also, negative values were obtained for energy as a function of the reaction coordinate for the regions where the formation of polar zippers occurs, showing that the lateral union of neighboring β-sheets is energetically favorable, with a value up to -3.0 kJ/mol, in the case of I₃NGK nanomembranes.

Advances in hybrid peptide-based self-assembly systems and their applications

Self-assembly of peptides demonstrates a great potential for designing highly ordered, finely tailored supramolecular arrangements enriched with high specificity, improved efficacy and biological activity. Along with natural peptides, hybrid peptide systems composed of natural and chemically diverse unnatural amino acids have been used in various fields, including drug delivery, wound healing, potent inhibition of diseases, and prevention of biomaterial related diseases to name a few. In this review, we provide a brief outline of various methods that have been utilized for obtaining fascinating structures that create an avenue to reproduce a range of functions resulting from these folds. An overview of different self-assembled structures as well as their applications will also be provided. We believe that this review is very relevant to the current scenario and will cover conformations of hybrid peptides and resulting self-assemblies from the late 20^th century through 2022. This review aims to be a comprehensive and reliable account of the hybrid peptide-based self-assembly owing to its enormous influence in understanding and mimicking biological processes.

Brij 30 Induced Transition of Rodlike Micelles to Wormlike Micelles and Gels in the Imidazole Ionic Liquid Surfactants: The Alkyl Chain Length Effect

The effect of the hydrocarbon chain length of ionic liquid surfactants 1-hexadecyl-3-alkyl imidazolium bromide [C₁₆imC_n]Br (n = 1-16) on their aggregation behavior with polyoxyethylene lauryl ether (Brij 30) in aqueous solution was inspected. The rheological behavior, thermal properties, and microstructures of the different samples were studied using freeze-fractured electron microscopy. The interactions between [C₁₆imC_n]Br and Brij 30 were studied using nuclear magnetic resonance spectroscopy and theoretical simulation. With the addition of Brij 30, the rodlike micelles of [C₁₆imC_n]Br (n = 1, 2, 4, and 6) transition into wormlike micelles. The effects of the molar ratio of Brij 30 and [C₁₆imC_n]Br and the hydrocarbon chain length of [C₁₆imC_n]Br on the Brij 30/[C₁₆imC_n]Br (n = 1, 2, 4, and 6) wormlike micelles were studied. When Brij 30 was mixed with the rodlike micelles of [C₁₆imC₈]Br, the Brij 30/[C₁₆imC₈]Br mixtures form wormlike micelles at low Brij 30 concentration and gels at high Brij 30 concentration. The [C₁₆imC_n]Br (n = 10, 12, 14, and 16) rodlike micelles were induced by Brij 30 to turn into the Brij 30/[C₁₆imC_n]Br gels. The effect of the [C₁₆imC_n]Br hydrocarbon chain length on their rodlike micelles with the addition of Brij 30 is also theoretically discussed.

Supramolecular Peptide Assemblies as Antimicrobial Scaffolds

Antimicrobial discovery in the age of antibiotic resistance has demanded the prioritization of non-conventional therapies that act on new targets or employ novel mechanisms. Among these, supramolecular antimicrobial peptide assemblies have emerged as attractive therapeutic platforms, operating as both the bactericidal agent and delivery vector for combinatorial antibiotics. Leveraging their programmable inter- and intra-molecular interactions, peptides can be engineered to form higher ordered monolithic or co-assembled structures, including nano-fibers, -nets, and -tubes, where their unique bifunctionalities often emerge from the supramolecular state. Further advancements have included the formation of macroscopic hydrogels that act as bioresponsive, bactericidal materials. This systematic review covers recent advances in the development of supramolecular antimicrobial peptide technologies and discusses their potential impact on future drug discovery efforts.

Modular self-assembly of gamma-modified peptide nucleic acids in organic solvent mixtures

Nucleic acid-based materials enable sub-nanometer precision in self-assembly for fields including biophysics, diagnostics, therapeutics, photonics, and nanofabrication. However, structural DNA nanotechnology has been limited to substantially hydrated media. Transfer to organic solvents commonly used in polymer and peptide synthesis results in the alteration of DNA helical structure or reduced thermal stabilities. Here we demonstrate that gamma-modified peptide nucleic acids (γPNA) can be used to enable formation of complex, self-assembling nanostructures in select polar aprotic organic solvent mixtures. However, unlike the diameter-monodisperse populations of nanofibers formed using analogous DNA approaches, γPNA structures appear to form bundles of nanofibers. A tight distribution of the nanofiber diameters could, however, be achieved in the presence of the surfactant SDS during self-assembly. We further demonstrate nanostructure morphology can be tuned by means of solvent solution and by strand substitution with DNA and unmodified PNA. This work thereby introduces a science of γPNA nanotechnology.

Effects of Conventional Surfactants on the Activity of Designed Antimicrobial Peptide

In this article, the interaction between a designed antimicrobial peptide (AMP) G(IIKK)₃I-NH₂ (G₃) and four typical conventional surfactants (sodium dodecyl sulfonate (SDS), hexadecyl trimethyl ammonium bromide (C₁₆TAB), polyoxyethylene (23) lauryl ether (C₁₂EO₂₃), and tetradecyldimethylamine oxide (C₁₄DMAO)) has been studied through surface tension measurement and circular dichroism (CD) spectroscopy. The antimicrobial activities of AMP/surfactant mixtures have also been studied with Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and the fungus Candida albicans. The cytotoxicity of the AMP/surfactant mixtures has also been assessed with NIH 3T3 and human skin fibroblast (HSF) cells. The surface tension data showed that the AMP/SDS mixture was much more surface-active than SDS alone. CD results showed that G₃ conformation changed from random coil, to β-sheet, and then to α-helix with increasing SDS concentration, showing a range of structural transformation driven by the different interactions with SDS. The antimicrobial activity of G₃ to Gram-negative and Gram-positive bacteria decreased in the presence of SDS due to the strong interaction of electrostatic attraction between the peptide and the surfactant. The interactions between G₃ and C₁₆TAB, C₁₂EO₂₃, and C₁₄DMAO were much weaker than SDS. As a result, the surface tension of surfactants with G₃ did not change much, neither did the secondary structures of G₃. The antimicrobial activities of G₃ were little affected in the presence of C₁₂EO₂₃, slightly improved by C₁₄DMAO, and clearly enhanced by cationic surfactant C₁₆TAB due to its strong cationic and antimicrobial nature, consistent with their surface physical activities as binary mixtures. Although AMP G₃ did not show activity to fungus, the mixtures of AMP/C₁₆TAB and AMP/C₁₄DMAO could kill C. albicans at high surfactant concentrations. The mixtures had rather high cytotoxicity to NIH 3T3 and HSF cells although G₃ is nontoxic to cells. Cationic AMPs can be formulated with nonionic, cationic, and zwitterionic surfactants during product development, but care must be taken when AMPs are formulated with anionic surfactants, as the strong electrostatic interaction may undermine their antimicrobial activity.

The design and biomedical applications of self-assembled two-dimensional organic biomaterials

Self-assembling 2D organic biomaterials exhibit versatile abilities for structural and functional tailoring, as well as high potential for biomedical applications.

Amphiphilic hydrogels for biomedical applications

We highlight the recent advances in the fabrication and biomedical application of amphiphilic hydrogels.

Click Synthesis of Shape-Persistent Azodendrimers and their Orthogonal Self-Assembly to Nanofibres

The copper(i)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction has been efficiently utilized to synthesize a series of dendrons with amino functionalities. The aminodendrons successfully underwent azodimerization to furnish a series of pyridyl- and phenyl-based azodendrimers with peripheral alkyl or ether side chain substituents. The molecular structures of the azodendrimers were fully assigned using different spectroscopic techniques, such as 1H NMR and 13C NMR, and the molecular weights were determined using MALDI-TOF mass spectrometry. The molecular self-assembly of the azodendrimers was investigated by scanning electron microscopy and transmission electron microscopy, which revealed the formation of highly ordered and uniform self-assembled nanofibres.