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Monoolein-based liquid crystal phases are established media that are researched for various biological applications, including drug delivery. While water is the most common solvent for self-assembly, some ionic liquids (ILs) can support lipidic self-assembly. However, currently, there is limited knowledge of IL-lipid phase behavior in ILs. In this study, the lyotropic liquid crystal phase behavior of monoolein was investigated in six protic ILs known to support amphiphile self-assembly, namely ethylammonium nitrate, ethanolammonium nitrate, ethylammonium formate, ethanolammonium formate, ethylammonium acetate, and ethanolammonium acetate. These ILs were selected to identify specific ion effects on monoolein self-assembly, specifically increasing the alkyl chain length of the cation or anion, the presence of a hydroxyl group in the cation, and varying the anion. The lyotropic liquid crystal phases with 20–80 wt. % of monoolein were characterized over a temperature range from 25 to 65 °C using synchrotron small angle x-ray scattering and cross-polarized optical microscopy. These results were used to construct partial phase diagrams of monoolein in each of the six protic ILs, with inverse hexagonal, bicontinuous cubic, and lamellar phases observed. Protic ILs containing the ethylammonium cation led to monoolein forming lamellar and bicontinuous cubic phases, while those containing the ethanolammonium cation formed inverse hexagonal and bicontinuous cubic phases. Protic ILs containing formate and acetate anions favored bicontinuous cubic phases across a broader range of protic IL concentrations than those containing the nitrate anion. [ABSTRACT FROM AUTHOR]

Regeneration of hyaline cartilage in human-sized joints remains a clinical challenge, and it is a critical unmet need that would contribute to longer healthspans. Injectable scaffolds for cartilage repair that integrate both bioactivity and sufficiently robust physical properties to withstand joint stresses offer a promising strategy. We report here on a hybrid biomaterial that combines a bioactive peptide amphiphile supramolecular polymer that specifically binds the chondrogenic cytokine transforming growth factor ß-1 (TGFß-1) and crosslinked hyaluronic acid microgels that drive formation of filament bundles, a hierarchical motif common in natural musculoskeletal tissues. The scaffold is an injectable slurry that generates a porous rubbery material when exposed to calcium ions once placed in cartilage defects. The hybrid material was found to support in vitro chondrogenic differentiation of encapsulated stem cells in response to sustained delivery of TGFß-1. Using a sheep model, we implanted the scaffold in shallow osteochondral defects and found it can remain localized in mechanically active joints. Evaluation of resected joints showed significantly improved repair of hyaline cartilage in osteochondral defects injected with the scaffold relative to defects injected with the growth factor alone, including implantation in the load-bearing femoral condyle. These results demonstrate the potential of the hybrid biomimetic scaffold as a niche to favor cartilage repair in mechanically active joints using a clinically relevant large-animal model. [ABSTRACT FROM AUTHOR]

Chemical Communications is a journal published by The Royal Society of Chemistry, which is a leading chemistry community. The journal features articles on various topics in the chemical sciences. The current issue includes articles on utilizing trees to produce advanced materials, the synthesis of borylated polyene building blocks, and the use of self-assembling short peptide amphiphiles as delivery agents in antibacterial research. It also includes communications on topics such as the reduction of SO2, the decomposition of ammonia, and the shaping of CPO-27-M through crystallization. The journal aims to provide original discoveries and contribute to scientific progress. [Extracted from the article]

Self-assembling short peptide amphiphiles, crafted through a minimalistic approach, spontaneously generate well-ordered nanostructures, facilitating the creation of precise nanostructured biomaterials for diverse biomedical applications. The seamless integration of bioactive metal ions and nanoparticles endows them with the potential to serve as pioneering materials in combating bacterial infections. Nanomanipulation of these molecules' binary structures enables effective penetration of membranes, forming structured nanoarchitectures with antibacterial properties. Through a comprehensive exploration, we attempt to reveal the innovative potential of short peptide amphiphiles, particularly in conjugation with metal cations and nanoparticles, offering insights for future research trajectories. [ABSTRACT FROM AUTHOR]

Amphiphilic peptides hold great potential as drug delivery systems. A popular peptide design approach has been to place amino acids in the peptide sequence based on their known properties. On the other hand, the directed discovery approach aims to screen a sequence space for a desired property. However, screening amphiphilic peptides for desirable drug delivery properties is not possible without a quantity that is predictive of these properties. We studied the predictive power of critical aggregation concentration (CAC) values on the drug delivery performance of a series of amphiphilic peptides with different hydrophobic tails and close CAC values. The CAC values were predicted by our previously developed model and doxorubicin was used as a model hydrophobic drug. All peptides showed close drug loading, entrapment efficiency, and release profile. They also formed similar spherical particles by assembling in reverse β -sheet arrangements regardless of drug presence. Moreover, the assembled particles were able to accumulate doxorubicin inside ordinary as well as drug-resistant breast cancer cells and enhance its toxicity up to 39 and 17 folds, respectively. It can be concluded that similar drug delivery properties displayed by the peptides can be attributed to their similar hydrophilic-lipophilic balance as reflected in their close CAC values. [Display omitted] • The designed amphiphilic peptides co-assembled with doxorubicin and decreased its IC50 in the ordinary and drug-resistant breast cancer cells up to 39 and 17 folds, respectively. • Amphiphilic peptides with different amino acids in their hydrophobic tails and close critical aggregation concentrations showed similar drug delivery performance. • Based on our results critical aggregation concentration can be an estimator of the drug delivery properties of self-assembling amphiphilic peptides. [ABSTRACT FROM AUTHOR]

Microvascular dysfunction following myocardial infarction exacerbates coronary flow obstruction and impairs the preservation of ventricular function. The apelinergic system, known for its pleiotropic effects on improving vascular function and repairing ischemic myocardium, has emerged as a promising therapeutic target for myocardial infarction. Despite its potential, the natural apelin peptide has an extremely short circulating half-life. Current apelin analogs have limited receptor binding efficacy and poor targeting, which restricts their clinical applications. In this study, we utilized an enzyme-responsive peptide self-assembly technique to develop an enzyme-responsive small molecule peptide that adapts to the expression levels of matrix metalloproteinases in myocardial infarction lesions. This peptide is engineered to respond to the high concentration of matrix metalloproteinases in the lesion area, allowing for precise and abundant presentation of the apelin motif. The changes in hydrophobicity allow the apelin motif to self-assemble into a supramolecular multivalent peptide ligand-SAMP. This self-assembly behavior not only prolongs the residence time of apelin in the myocardial infarction lesion but also enhances the receptor-ligand interaction through increased receptor binding affinity due to multivalency. Studies have demonstrated that SAMP significantly promotes angiogenesis after ischemia, reduces cardiomyocyte apoptosis, and improves cardiac function. This novel therapeutic strategy offers a new approach to restoring coronary microvascular function and improving damaged myocardium after myocardial infarction. [Display omitted] • An MMP-induced self-assembling Apelin ligand (SAMP) was developed for myocardial infarction (MI) therapy. • SAMP self-adaptively assembles in situ into stable, high-affinity Apelin-based nanofibers in the MI microenvironment. • SAMP multivalently activates AplnR, promotes angiogenesis, inhibits cardiomyocyte apoptosis, and improves cardiac function.SAMP multivalently activates AplnR, promotes angiogenesis, inhibits cardiomyocyte apoptosis, and improves cardiac function. [ABSTRACT FROM AUTHOR]

Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal interstitial lung disease, with limited therapeutic options available. Impaired autophagy resulting from aberrant TRB3/p62 protein‐protein interactions (PPIs) contributes to the progression of IPF. Restoration of autophagy by modulating the TRB3/p62 PPIs has rarely been reported for the treatment of IPF. Herein, peptide nanofibers are developed that specifically bind to TRB3 protein and explored their potential as a therapeutic approach for IPF. By conjugating with the self‐assembling fragment (Ac‐GFFY), a TRB3‐binding peptide motif A2 allows for the formation of nanofibers with a stable α‐helix secondary structure. The resulting peptide (Ac‐GFFY‐A2) nanofibers exhibit specific high‐affinity binding to TRB3 protein in saline buffer and better capacity of cellular uptake to A2 peptide. Furthermore, the TRB3‐targeting peptide nanofibers efficiently interfere with the aberrant TRB3/p62 PPIs in activated fibroblasts and fibrotic lung tissue of mice, thereby restoring autophagy dysfunction. The TRB3‐targeting peptide nanofibers inhibit myofibroblast differentiation, collagen production, and fibroblast migration in vitro is demonstrated, as well as bleomycin‐induced pulmonary fibrosis in vivo. This study provides a supramolecular method to modulate PPIs and highlights a promising strategy for treating IPF diseases by restoring autophagy. [ABSTRACT FROM AUTHOR]

Photodynamic therapy shows promise for glioma treatment with powerful efficacy and low resistance, however, its effectiveness is significantly lowered by inadequate light delivery through the skull. Herein, a needle‐type implantable microLED device and cathepsin B‐responsive prodrug nanoparticles (PNPs) are newly exploited for glioma's chemo‐photodynamic combination therapy. The microLED containing four small LEDs on the tip of its guide needle can be implanted into the center of glioma tissues without large area opening of skull, uniformly irradiating light to deep glioma tissues. PNPs are formulated via self‐assembly of heterobifunctional prodrug composed of doxorubicin, verteporfin, and cathepsin B‐cleavable peptide linker, wherein they stably maintain inactive nanoparticle structures in normal physiological conditions and specifically deliver therapeutic age to cathepsin B‐overexpressed glioma tissues. In vitro cellular assays, PNPs irradiated with showed the synergistic cytotoxicity of DOX and VFP only in cathepsin B‐overexpressed cancer cells rather than normal cells. In tumor‐bearing mice, PNPs showed high tumor accumulation via the nanoparticle‐driven enhanced permeation and retention (EPR) effect and they also exhibited remarkable therapeutic efficacy against glioma under microLED‐mediated light irradiation via chemo‐photodynamic combination therapy. Accordingly, applying microLED with PNPs is an outstanding strategy to defeat glioma with cooperative chemo‐photodynamic effects, minimal invasiveness, and desirable systemic/local safety. [ABSTRACT FROM AUTHOR]

Self‐assembling peptides have numerous applications in medicine, food chemistry, and nanotechnology. However, their discovery has traditionally been serendipitous rather than driven by rational design. Here, HydrogelFinder, a foundation model is developed for the rational design of self‐assembling peptides from scratch. This model explores the self‐assembly properties by molecular structure, leveraging 1,377 self‐assembling non‐peptidal small molecules to navigate chemical space and improve structural diversity. Utilizing HydrogelFinder, 111 peptide candidates are generated and synthesized 17 peptides, subsequently experimentally validating the self‐assembly and biophysical characteristics of nine peptides ranging from 1–10 amino acids—all achieved within a 19‐day workflow. Notably, the two de novo‐designed self‐assembling peptides demonstrated low cytotoxicity and biocompatibility, as confirmed by live/dead assays. This work highlights the capacity of HydrogelFinder to diversify the design of self‐assembling peptides through non‐peptidal small molecules, offering a powerful toolkit and paradigm for future peptide discovery endeavors. [ABSTRACT FROM AUTHOR]

The capability of peptide and amino acid‐based molecules to act as ionogelators and eutectogelators entrapping ionic liquids (ILs) and deep eutectic solvents (DESs) forming ionogels and eutectogels has gathered attention in recent decades. The self‐assembly process, primarily driven by non‐covalent interactions as hydrogen bonding, remains serendipitous in nature. This review provides a comprehensive and detailed report on self‐assembly of unmodified and modified amino acids and peptides in the non‐conventional solvents, ILs and DESs. Understanding these processes holds great promise for the development of innovative soft‐materials, and to the progress of supramolecular systems in non‐conventional solvent environments. [ABSTRACT FROM AUTHOR]

Alpha-helical AMPs' specific targeting on both cell wall and cytoplasmic membrane of Gram-positive S. aureus , and their obvious behaviour of inducing membrane microphase-separation in bacterial killing. [Display omitted] Multidrug resistance (MDR) is a rising threat to global health because the number of essential antibiotics used for treating MDR infections is increasingly compromised. In this work we report a group of new amphiphilic peptides (AMPs) derived from the well-studied G 3 (G(IIKK) 3 I-NH 2) to fight infections from Gram-positive bacteria including susceptible Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA), focusing on membrane interactions. Time-dependent killing experiments revealed that substitutions of II by WW (GWK), II by FF (GFK) and KK by RR (GIR) resulted in improved bactericidal efficiencies compared to G 3 (GIK) on both S. aureus and MRSA, with the order of GWK > GIR > GFK > GIK. Electronic microscopy imaging revealed structural disruptions of AMP binding to bacterial cell walls. Fluorescence assays including AMP binding to anionic lipoteichoic acids (LTA) in cell-free and cell systems indicated concentration and time-dependent membrane destabilization associated with bacterial killing. Furthermore, AMP's binding to anionic plasma membrane via similar fluorescence assays revealed a different extent of membrane depolarization and leakage. These observations were supported by the penetration of AMPs into the LTA barrier and the subsequent structural compromise to the cytoplasmic membrane as revealed from SANS (small angle neutron scattering). Both experiments and molecular dynamics (MD) simulations revealed that GWK and GIR could make the membrane more rigid but less effective in diffusive efficiency than GIK and GFK through forming intramembrane peptide nanoaggregates associated with hydrophobic mismatch and formation of fluidic and rigid patches. The reported peptide-aggregate-induced phase-separation emerged as a crucial factor in accelerated membrane disintegration and fast bacterial killing. This work has demonstrated the importance of membrane interactions to the development of more effective AMPs and the relevance of the approaches as reported in assisting this area of research. [ABSTRACT FROM AUTHOR]

A green strategy for the selective alkylation of cysteine-containing peptides in a continuous flow reactor has been developed, providing an efficient pathway to alkylated cysteine-containing peptides under mild conditions. This process does not need light, metal catalysts, or oxidative reagents. It provides a useful method for the modification of amino acids and peptides. As one of the low cost and synthetic versatile raw materials, the alkyl thianthenium salt can be used as an alkylation source in the preparation of alkylated cysteine-containing peptides. In addition, the microfluidics technology can shorten the reaction time and improve the efficiency, thus reducing the costs and energy consumption of the synthesis process. A series of alkylated cysteine-containing peptides (41 examples) has been synthesized here with a short residence time (14.0 min), and with good to excellent yields. [ABSTRACT FROM AUTHOR]

Fluorinated non‐natural amino acids are attracting considerable research interest, especially in the biomedical field and in materials science, thanks to their ability to self‐assemble into peculiar supramolecular structures. The conformational changes induced by the presence of fluorine atoms obviously affect their functions, as well as the biological activity of the deriving peptides and proteins. Here, we will briefly describe the main effects of fluorination on the aggregation behavior of such building blocks, focusing in particular on their improved tendency to form fibrils, and gels therefrom. Our aim is to underline the promising potential of fluorination as a tool to affect the self‐assembly features of amino acids, both when used alone and when inserted into polypeptide sequences. The ability of fluorine to influence physical, chemical, and structural properties of these substrates offers the possibility to engineer bioinspired materials with specific and tunable functions. [ABSTRACT FROM AUTHOR]

Based on the whole virus or spike protein of pigs, d coronavirus (PDCoV) as an immunogen may have unrelated antigenic epitope interference. Therefore, it is essential for screening and identifying advantageous protective antigen epitopes. In addition, immunoinformatic tools are described as an important aid in determining protective antigenic epitopes. In this study, the primary, secondary, and tertiary structures of vaccines were measured using ExPASy, PSIPRED 4.0, and trRosetta servers. Meanwhile, the molecular docking analysis and vector of the candidate nanovaccine were constructed. The immune response of the candidate vaccine was simulated and predicted using the C-ImmSim server. This experiment screened B cell epitopes with strong immunogenicity and high conservation, CTL epitopes, and Th epitopes with IFN-γ and IL-4 positive spike proteins. Ferritin is used as a self-assembled nanoparticle element for designing candidate nanovaccine. After analysis, it has been found to be soluble, stable, non-allergenic, and has a high affinity for its target receptor, TLR-3. The preliminary simulation analysis results show that the candidate nanovaccine has the ability to induce a humoral and cellular immune response. Therefore, it may provide a new theoretical basis for research on coronavirus self-assembled nanovaccines. It may be an effective candidate vaccine for controlling and preventing PDCoV. [ABSTRACT FROM AUTHOR]

[Display omitted] A benzoic acid (BA) disk was investigated as a novel self-propelled object whose driving force was the difference in surface tension. 4-Stearoyl amidobenzoic acid (SABA) was synthesized as an amphiphile to control the nature of motion based on intermolecular interactions between BA and SABA. The BA disk exhibited characteristic motion depending on the surface density of the SABA on the aqueous phase, that is, reciprocating motion as a one-dimensional motion and restricted and unrestricted motion as a two-dimensional motion. The trajectory of the reciprocating motion was determined by the initial direction of motion, and the boundary between an aqueous surface and the BA-SABA condensed molecular layer was used as the field's boundary. The presented results indicate that the characteristic nature of motion can be designed at the molecular level based on the intermolecular interactions between an energy-source molecule and an amphiphile. [ABSTRACT FROM AUTHOR]

Bacterial microcompartments are prokaryotic organelles comprising encapsulated enzymes within a thin protein shell. They facilitate metabolic processing including propanediol, choline, glycerol, and ethanolamine utilization, and they accelerate carbon fixation in cyanobacteria. Enzymes targeted to the inside of the microcompartment frequently possess a cargo-encapsulation peptide, but the site to which the peptide binds is unclear. We provide evidence that the encapsulation peptides bind to the hydrophobic groove formed between tessellating subunits of the shell proteins. In silico docking studies provide a compelling model of peptide binding to this prominent hydrophobic groove. This result is consistent with the now widely accepted view that the convex side of the shell oligomers faces the lumen of the microcompartment. The binding of the encapsulation peptide to the groove between tessellating shell protein tiles explains why it has been difficult to define the peptide binding site using other methods, provides a mechanism by which encapsulation-peptide bearing enzymes can promote shell assembly, and explains how the presence of cargo affects the size and shape of the bacterial microcompartment. This knowledge may be exploited in engineering microcompartments or disease prevention by hampering cargo encapsulation. [ABSTRACT FROM AUTHOR]

Targeting immunosuppressive metastatic cancer cells is a key challenge in therapy. We recently have shown that a rigid‐rod aromatic, pBP−NBD, that responds to enzymes and kill immunosuppressive metastatic osteosarcoma (mOS) and castration resistant prostate cancer (CRPC) cells in mimetic bone microenvironment. However, pBP−NBD demonstrated moderate efficacy against CRPC cells. To enhance activity, we incorporated the unnatural amino acid L‐ or D‐4,4′‐biphenylalanine (L‐ or D−BiP) into pBP−NBD, drastically increasing cellular uptake and CRPC inhibition. Specifically, we inserted BiP into pBP−NBD to target mOS (Saos2 and SJSA1) and CRPC (VCaP and PC3) cells with overexpressed phosphatases. Our results show that the D‐peptide backbone with an aspartate methyl diester at the C‐terminal offers the highest activity against these immunosuppressive mOS and CRPC cells. Importantly, imaging shows that the peptide assemblies almost instantly enter the cells and accumulate primarily within the endoplasmic reticulum of Saos2, SJSA1, and PC3 cells and at the lysosomes of VCaP cells. By using BiP to boost cellular uptake and self‐assembly within cancer cells, this work illustrates an unnatural hydrophobic amino acid as a versatile and effective residue to boost endocytosis of synthetic peptides for intracellular self‐assembly. [ABSTRACT FROM AUTHOR]

The rising prevalence of global antibiotic resistance evokes the urgent need for novel antimicrobial candidates. Cationic lipopeptides have attracted much attention due to their strong antimicrobial activity, broad‐spectrum and low resistance tendency. Herein, a library of fluoro‐lipopeptide amphiphiles was synthesized by tagging a series of cationic oligopeptides with a fluoroalkyl tail via a disulfide spacer. Among the lipopeptide candidates, R6F bearing six arginine moieties and a fluorous tag shows the highest antibacterial activity, and it exhibits an interesting fluorine effect as compared to the non‐fluorinated lipopeptides. The high antibacterial activity of R6F is attributed to its excellent bacterial membrane permeability, which further disrupts the respiratory chain redox stress and cell wall biosynthesis of the bacteria. By co‐assembling with lipid nanoparticles, R6F showed high therapeutic efficacy and minimal adverse effects in the treatment of MRSA‐induced sepsis and chronic wound infection. This work provides a novel strategy to design highly potent antibacterial peptide amphiphiles for the treatment of drug‐resistant bacterial infections. [ABSTRACT FROM AUTHOR]

L / D -Phenylglycine amphiphiles and metal ions with peroxidase-like activity self-assembled into chiral nanoribbons, which act as efficient chiral supramolecular nanozymes for catalyzing the 3,4-dihydroxy- L / D -phenylalanine (L / D -DOPA) oxidation reactions. The catalytic efficiency and enantioselectivity are dominated by the chirality transfer and the synergistic effect between the metal ions and chiral nanoribbons. [ABSTRACT FROM AUTHOR]

In recent decades, peptide amphiphiles (PAs) have established themselves as promising self-assembling bioinspired materials in a wide range of medical fields. Herein, we report a dual-therapeutic system constituted by an antimicrobial PA and a cylindrical protease inhibitor (LJC) to achieve broad antimicrobial spectrum and to enhance therapeutic efficacy. We studied two strategies: PA-LJC nanostructures (Encapsulation) and PA nanostructures + free LJC (Combination). Computational modeling using a molecular theory for amphiphile self-assembly captures and explains the morphology of PA-LJC nanostructures and the location of encapsulated LJC in agreement with transmission electron microscopy and two-dimensional (2D) NMR observations. The morphology and release profile of PA-LJC assemblies are strongly correlated to the PA:LJC ratio: high LJC loading induces an initial burst release. We then evaluated the antimicrobial activity of our nanosystems toward gram-positive and gram-negative bacteria. We found that the Combination broadens the spectrum of LJC, reduces the therapeutic concentrations of both agents, and is not impacted by the inoculum effect. Further, the Encapsulation provides additional benefits including bypassing water solubility limitations of LJC and modulating the release of this molecule. The different properties of PA-LJC nanostructures results in different killing profiles, and reduced cytotoxicity and hemolytic activity. Meanwhile, details in membrane alterations caused by each strategy were revealed by various microscopy and fluorescent techniques. Last, in vivo studies in larvae treated by the Encapsulation strategy showed better antimicrobial efficacy than polymyxin B. Collectively, this study established a multifunctional platform using a versatile PA to act as an antibiotic, membrane-penetrating assistant, and slow-release delivery vehicle. [ABSTRACT FROM AUTHOR]

Cell therapies offer great promise in the treatment of diseases and tissue regeneration, but their clinical use has many challenges including survival, optimal performance in their intended function, or localization at sites where they are needed for effective outcomes. We report here on a method to coat a biodegradable matrix of biomimetic nanofibers on single cells that could have specific functions ranging from cell signaling to targeting and helping cells survive when used for therapies. The fibers are composed of peptide amphiphile (PA) molecules that self-assemble into supramolecular nanoscale filaments. The PA nanofibers were able to create a mesh-like coating for a wide range of cell lineages with nearly 100 % efficiency, without interrupting the natural cellular phenotype or functions. The targeting abilities of this system were assessed in vitro using human primary regulatory T (hTreg) cells coated with PAs displaying a vascular cell adhesion protein 1 (VCAM-1) targeting motif. This approach provides a biocompatible method for single-cell coating that does not negatively alter cellular phenotype, binding capacity, or immunosuppressive functionality, with potential utility across a broad spectrum of cell therapies. Cell therapies hold great promise in the treatment of diseases and tissue regeneration, but their clinical use has been limited by cell survival, targeting, and function. We report here a method to coat single cells with a biodegradable matrix of biomimetic nanofibers composed of peptide amphiphile (PA) molecules. The nanofibers were able to coat cells, such as human primary regulatory T cells, with nearly 100 % efficiency, without interrupting the natural cellular phenotype or functions. The approach provides a biocompatible method for single-cell coating that does not negatively alter cellular phenotype, binding capacity, or immunosuppressive functionality, with potential utility across a broad spectrum of cell therapies. [Display omitted] [ABSTRACT FROM AUTHOR]

Antimicrobial peptide amphiphiles (PAs) are a promising class of molecules that can disrupt the bacterial membrane or act as drug nanocarriers. In this study, we prepared 33 PAs to establish supramolecular structure‐activity relationships. We studied the morphology and activity of the nanostructures against different Gram‐positive and Gram‐negative bacterial strains (such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii). Next, we used principal component analysis (PCA) to determine the key contributors to activity. We found that for S. aureus, the zeta potential was the major contributor to the activity while Gram‐negative bacteria were more influenced by the partition coefficient (LogP) with the following order P. aeruginosa>E. coli>A. baumannii. We also performed a study of the mechanism of action of selected PAs on the bacterial membrane assessing the membrane permeability and depolarization, changes in zeta potential and overall integrity. We studied the toxicity of the nanostructures against mammalian cells. Finally, we performed an in vivo study using the wax moth larvae to determine the therapeutic efficacy of the active PAs. This study shows cationic PA nanostructures can be an intriguing platform for the development of nanoantibacterials. [ABSTRACT FROM AUTHOR]

Non-viral vectors have been developing in gene delivery due to their safety and low immunogenicity. But their transfection effect is usually very low, thus limiting the application. Hence, we designed eight peptides (compounds 1–8). We compared their performances; compound 8 had the best transfection efficacy and biocompatibility. The transfection effect was similar with that of PEI, a most-widely-employed commercial transfection reagent. Atomic force microscope (AFM) images showed that the compound could self-assemble and the self-assembled peptide might encapsulate DNA. Based on these results, we further analyzed the inhibitory result in cancer cells and found that compound 8 could partially fight against Hela cells. Therefore, the compound is promising to pave the way for the development of more effective and less toxic transfection vectors. [ABSTRACT FROM AUTHOR]

Developing peptide‐based materials with controlled morphology is a critical theme of soft matter research. Herein, we report the formation of a novel, patterned cross‐β structure formed by self‐assembled C3‐symmetric peptide amphiphiles based on diphenylalanine and benzene‐1,3,5‐tricarboxamide (BTA). The cross‐β motif is an abundant structural element in amyloid fibrils and aggregates of fibril‐forming peptides, including diphenylalanine. The incorporation of topological constraints on one edge of the diphenylalanine fragment limits the number of β‐strands in β‐sheets and leads to the creation of an unconventional offset‐patterned cross‐β structure consisting of short 3×2 parallel β‐sheets stabilized by phenylalanine zippers. In the reported assembly, two patterned cross‐β structures bind parallel arrays of BTA stacks in a superstructure within a single‐molecule‐thick nanoribbon. In addition to a threefold network of hydrogen bonds in the BTA stack, each molecule becomes simultaneously bound by hydrogen bonds from three β‐sheets and four phenylalanine zippers. The diffuse layer of alkyl chains with terminal polar groups prevents the nanoribbons from merging and stabilizes cross‐β‐structure in water. Our results provide a simple approach to the incorporation of novel patterned cross‐β motifs into supramolecular superstructures and shed light on the general mechanism of β‐sheet formation in C3‐symmetric peptide amphiphiles. [ABSTRACT FROM AUTHOR]

[Display omitted] Semifluorinated alkanes amphiphiles spontaneously form highly monodispersed hemimicelles at the surface of water. The origin of the formation and complex structure of these surprising supramolecular aggregates were only recently clarified using molecular dynamics simulations (MD). The existence of a pit at the center of these aggregates made up of almost 3000 molecules was indeed reproduced by the MD simulations, but not understood. A careful strategy of atomistic MD simulations comparing non-electrostatic force fields with force fields that include electrostatic forces, thus bearing an implicit or explicit dipole, allowed demonstrating the roles of dipolar interactions and interactions with the liquid subphase on the morphology of the aggregates. The simulation results clearly show that within the hemimicelles the strong molecular dipoles located at the CH 2 -CF 2 junctions tend to align, leading to a collective shift of the PFAA molecules relatively to each other. This shift is responsible for the curvature of the hemimicelles and originates the central pit, provided the possibility of deforming the surface of the water sub-phase. Comparisons with non-electrostatic force field results further contribute to understand the origin of the self-assembling process. The results directly connect for the first time a molecular property with a mesoscopic structural feature. Given the molecular simplicity of these "primitive" amphiphiles compared to the common hydrophilic/hydrophobic surfactants, the results contribute to understand self-assembly in general. [ABSTRACT FROM AUTHOR]

Anion-induced self-assembly is one of the growing research fields as it provides a better understanding of natural self-assemblies such as DNA, proteins, peptides, etc. Peptides are well known for their aggregation properties owing to their hydrogen bonding interactions. Herein, nanohybrids of the glutathione tripeptide and naphthalimide based compounds were fabricated, in order to explore their self-assembly behaviour. The naphthalimide based compounds were processed into organic nanoparticles using a re-precipitation method and then into nanohybrids with a tripeptide under ultrasonication conditions to get nanohybrids NH-1, NH-2 and NH-3. The morphology of prepared nanohybrids was studied by HRTEM analysis. The photophysical studies of these nanohybrids were carried out by adding various anions. NH-1 shows enhanced fluorescence intensity with bisulphate anions and the rest of the anions do not induce any change in the fluorescence intensity. Furthermore, the morphology of these nanohybrids was monitored using HRTEM and STEM. With bisulphate anions, a beautiful butterfly shaped self-assembly was observed for NH-1. The increase in intensity was a result of the aggregation induced enhanced emission mechanism. These self-assemblies have potential applications in the recognition of bisulphate with a limit of detection (LOD) of 3 nM and a limit of quantification of 10 nM respectively. [ABSTRACT FROM AUTHOR]

DNA is self-assembled with Fmoc-amino acids and Cu2+ to construct a supramolecular catechol oxidase-mimetic catalyst, which exhibits remarkable activity in catalyzing colorimetric reactions. This catalytic system is used for the detection of DNA hybridization with a high selectivity and a low detection limit. [ABSTRACT FROM AUTHOR]

[Display omitted] Self-assembly of macroscopic membranes at the interface between self-assembling peptides and aqueous polymer solutions of opposite charge has been explored mostly due to the membranes' unique hierarchical structure of three distinct regions, including a layer of perpendicular fibers. We report here on the formation and characterization of self-assembled membranes made with λ-carrageenan and the cationic β-sheet peptides, Pro-Lys-(Phe-Lys) 5 -Pro (PFK). Using SAXS, SEM, ITC, and rheology, we compared these membranes' morphology and physical properties to membranes made with alginate. We recognized that the polysaccharide's single chain conformation, its solution's viscosity, the potential of hydrogen bonding and electrostatic interactions between the polysaccharides and the peptides charged groups, and the strength of these interactions all affect the properties of the resulting membranes. As a result, we identified that an interplay between the polymer-peptide strength of interactions and the stiffness of the polysaccharide's single chain could be used as a route to control the structure–function relationship of the membranes. These results provide valuable information for creating guidelines to design self-assembly membranes with specific properties. [ABSTRACT FROM AUTHOR]

In our ongoing quest to design effective antimicrobial peptides (AMPs), this study aimed to elucidate the mechanisms governing cyclic amphiphilic AMPs and their interactions with membranes. The objective was to discern the nature of these interactions and understand how peptide sequence and structure influence antimicrobial activity. We introduced modifications into the established cyclic AMP peptide, [W4R4], incorporating an extra aromatic hydrophobic residue (W), a positively charged residue (R), or the unique 2,5-diketopiperazine (DKP). This study systematically explored the structure–activity relationships (SARs) of a series of cyclic peptides derived from the [W4R4] scaffold, including the first synthesis and evaluation of [W4R4(DKP)]. Structural, dynamic, hydrophobic, and membrane-binding properties of four cyclic peptides ([W4R4], [W5R4], [W4R5], [W4R4(DKP)]) were explored using molecular dynamics simulations within a DOPC/DOPG lipid bilayer that mimics the bacterial membrane. The results revealed distinct SARs linking antimicrobial activity to parameters such as conformational plasticity, immersion depth in the bilayer, and population of the membrane binding mode. Notably, [W4R5] exhibited an optimal "activity/binding to the bacterial membrane" pattern. This multidisciplinary approach efficiently decoded finely regulated SAR profiles, laying a foundation for the rational design of novel antimicrobial peptides. [ABSTRACT FROM AUTHOR]

Pseudopeptide-based soft bioinspired materials have recently emerged as state-of-the-art soft matter for recognition and supramolecular self-assembly. Therefore, we synthesized L -valine and L -phenylalanine-based C2-symmetric pseudo-peptidic soft bioinspired materials for the selective and sensitive detection of Cu(II) ions in aqueous-organic media through the CHEQ mechanism. These pseudopeptides show 2 : 1 stoichiometry with Cu(II), with a high value of binding constant (Ka = 0.035 × 105 M−1, 0.02 × 105 M−1) and low detection (0.053 ppm and 0.0047 ppm), respectively, for 1 and 2. Also, the Cu(II) guided tuning of supramolecular nano-assembly is a promising field for material nano-architectonics applications. [ABSTRACT FROM AUTHOR]

Herein, we designed alkylated lysine-dendron oxytocin amphiphiles (ALOAs) 1G-OTK and 2G-OTK, which were self-assembled into spherical nanoparticles and nanostrips, respectively, and showed superior stability compared to native oxytocin. We found similar trends in the functional activity of ALOAs and native OT for human oxytocin receptor. This work may inspire the development of peptide drugs for clinical applications. [ABSTRACT FROM AUTHOR]

Co-assembling peptides can be crafted into supramolecular biomaterials for use in biotechnological applications, such as cell culture scaffolds, drug delivery, biosensors, and tissue engineering. Peptide co-assembly refers to the spontaneous organization of two different peptides into a supramolecular architecture. Here we use molecular dynamics simulations to quantify the effect of anionic amino acid type on co-assembly dynamics and nanofiber structure in binary CATCH(+/-) peptide systems. CATCH peptide sequences follow a general pattern: CQCFCFCFCQC, where all C's are either a positively charged or a negatively charged amino acid. Specifically, we investigate the effect of substituting aspartic acid residues for the glutamic acid residues in the established CATCH(6E-) molecule, while keeping CATCH(6K+) unchanged. Our results show that structures consisting of CATCH(6K+) and CATCH(6D-) form flatter β-sheets, have stronger interactions between charged residues on opposing β-sheet faces, and have slower co-assembly kinetics than structures consisting of CATCH(6K+) and CATCH(6E-). Knowledge of the effect of sidechain type on assembly dynamics and fibrillar structure can help guide the development of advanced biomaterials and grant insight into sequence-to-structure relationships. Author summary: Peptides are great building blocks for supramolecular biomaterials—with applications in drug delivery, tissue engineering, and so forth. Peptide co-assembly refers to the spontaneous coming together of mixtures containing two different peptides to form organized structures. CATCH (Co-Assembly Tags based on CHarge complementarity) are mixtures of oppositely charged peptides that co-assemble into β-sheet nanofibers. CATCH peptide sequences follow a general pattern: CQCFCFCFCQC, where all C's are either a positively charged or a negatively charged amino acid. In this study, we use molecular dynamics simulations to determine the effect of negative amino acid type on co-assembly dynamics and nanofiber structure, specifically the difference between incorporating glutamic acid (E-) and aspartic acid (D-). Our results show that structures created using aspartic acid (D-) form flatter β-sheets and have slower co-assembly kinetics than structures created with glutamic acid (E-). Understanding the effect of different amino acid types on peptide assembly and nanofiber properties will allow us to design biomaterials with predetermined structural properties. [ABSTRACT FROM AUTHOR]

Degenerative spine disease is increasing in prevalence as the global population ages, indicating a need for targeted therapies and continued innovations. While autograft and allograft have historically demonstrated robust results in spine fusion surgery, they have significant limitations and associated complications such as infection, donor site morbidity and pain, and neurovascular injury. Synthetic grafts may provide similar success while mitigating negative outcomes. A narrative literature review was performed to review available synthetic materials that aim to optimize spinal fusion. The authors specifically address the evolution of synthetics and comment on future trends. Novel synthetic materials currently in use include ceramics, synthetic polymers and peptides, bioactive glasses, and peptide amphiphiles, and the authors focus on their success in both human and animal models, physical properties, advantages, and disadvantages. Advantages include properties of osteoinduction, osteoconduction, and osteogenesis, whereas disadvantages encompass a lack of these properties or growth factor-induced complications. Typically, the use of synthetic materials results in fewer complications and lower costs. While the development and tuning of synthetic materials are ongoing, there are many beneficial alternatives to autografts and allografts with promising fusion results. [ABSTRACT FROM AUTHOR]

Bio‐inspired design of peptides represents one facile strategy for development of supramolecular monomers for self‐assembly into well‐defined nanostructures. Inspired by methylation of arginine during post‐translational modification for manipulating protein functions, herein, the controllable self‐assembly of peptides via rational incorporation of methylated arginine residues into bola‐amphiphilic peptides is reported. A series of bola‐amphiphilic peptides are designed and synthesized either containing natural arginine or methylated arginine and investigate the influence of arginine methylation on peptide assembly. This study finds that incorporation of symmetrically di‐methylated arginine into oppositely charged hexapeptide hex‐SDMAE leads to distinct assembling performance compare to natural peptide hex‐RE. The findings demonstrate that the methylation of rationally designed peptide sequences allows for regulation of self‐assembly of peptides, thus implying the great potential of arginine methylation in establishing controllable peptide assembling systems and creating in situ formulation of biomedical materials in the future. [ABSTRACT FROM AUTHOR]

Proteins and peptides with hydrophobic and amphiphilic segments are responsible for many biological functions. The sensing and generation of membrane curvature are the functions of several protein domains or motifs. While some specific membrane proteins play an essential role in controlling the curvature of distinct intracellular membranes, others participate in various cellular processes such as clathrin-mediated endocytosis, where several proteins sort themselves at the neck of the membrane bud. A few membrane-inserting proteins form nanopores that permeate selective ions and water to cross the membrane. In addition, many natural and synthetic small peptides and protein toxins disrupt the membrane by inducing nonspecific pores in the membrane. The pore formation causes cell death through the uncontrolled exchange between interior and exterior cellular contents. In this article, we discuss the insertion depth and orientation of protein/peptide helices, and their role as a sensor and inducer of membrane curvature as well as a pore former in the membrane. We anticipate that this extensive review will assist biophysicists to gain insight into curvature sensing, generation, and pore formation by membrane insertion. [ABSTRACT FROM AUTHOR]

The development of straightforward synthetic and characterization methods for selenopeptides is essential to discovering hierarchical structured functional materials. Here, the synthesis of a series of homo-selenopeptides 1-4, having the benzyl (Bzl) group-protected selenocysteine [(Bzl)SeCH2CH(NH2)COOH] monomer units in the sequence, is reported. The homo-selenopeptides 1-4 are characterized by 1D (1H, 13C, and 77Se) and 2D (1H-1H COSY, 1H-1H NOESY, and 1H-1H TOCSY) NMR spectroscopy, and ESI-MS spectrometry. The triselenopeptide 1 shows a propensity for self-assembly into β-sheet amyloid-like fibril structure in acetonitrile (ACN) solution at room temperature. This has systematically been analyzed and established through the spectroscopic techniques; FT-IR, CD, and ThT-based fluorescence spectroscopy for secondary bonding analyses and microscopic techniques; SEM and TEM for the amyloid-like fibril structure in ACN solution. The amide I band vibrational stretching frequencies observed in the range 1600-1700 cm−1 confirm that all peptides in the homologous series have a strong propensity to form amyloid-like fibril structures. Synthesis of a series of homo-selenopeptides 1-4 through the solid-phase peptide synthesis (SPPS), using Fmoc protected Sec(Bzl)-OH as a source of amino acid, has been described. Spectroscopic and morphological imaging studies revealed that the homo-selenopeptides have a high propensity to get self-organized into amyloid-like fibrillar structures. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides are promising alternatives to conventional antibiotics. Herein, we report a class of "tadpole-like" peptides consisting of an amphipathic α-helical head and an aromatic tail. A structure-activity relationship (SAR) study of "tadpole-like" temporin-SHf and its analogs revealed that increasing the number of aromatic residues in the tail, introducing Arg to the α-helical head and rearranging the peptide topology dramatically increased antimicrobial activity. Through progressive structural optimization, we obtained two peptides, HT2 and RI-HT2, which exhibited potent antimicrobial activity, no hemolytic activity and cytotoxicity, and no propensity to induce resistance. NMR and molecular dynamics simulations revealed that both peptides indeed adopted "tadpole-like" conformations. Fluorescence experiments and electron microscopy confirmed the membrane targeting mechanisms of the peptides. Our studies not only lead to the discovery of a series of ultrashort peptides with potent broad-spectrum antimicrobial activities, but also provide a new strategy for rational design of novel "tadpole-like" antimicrobial peptides. Here, through progressive structural optimization, two "tadpole-like" antimicrobial peptides are constructed with an amphipathic α-helical head and an aromatic tail activity. These exhibit potent antimicrobial activity, no hemolytic activity and cytotoxicity, and no propensity to induce resistance. [ABSTRACT FROM AUTHOR]

Membraneless organelles formed via the self-assembly of intrinsically disordered proteins (IDPs) play a crucial role in regulating various physiological functions. Elucidating the mechanisms behind IDP self-assembly is of great interest not only from a biological perspective but also for understanding how amino acid mutations in IDPs contribute to the development of neurodegenerative diseases and other disorders. Currently, two proposed mechanisms explain IDP self-assembly: (1) the sticker-and-spacer framework, which considers amino acid residues as beads to simulate the intermolecular interactions, and (2) the cross-β hypothesis, which focuses on the β-sheet interactions between the molecular surfaces constructed by multiple residues. This review explores the advancement of new models that provide higher resolution insights into the IDP self-assembly mechanism based on new findings obtained from structural studies of IDPs. [ABSTRACT FROM AUTHOR]

Pseudopeptides are a versatile class of organic building blocks having potential applications in a wide range of domains. In the current study, N and C termini protected l-alanine based short pseudopeptide was synthesized, where 5-aminoisophthalic acid (5-AIA), a rigid non-proteogenic γ-amino butyric acid was incorporated as C-terminal residue. The single crystal X-ray analysis revealed that the l-Ala residue of the aforesaid peptide adopts ϕ and ψ values characteristic of polyproline II conformation. Self-assembly of the pseudopeptide seems to represent a supramolecular helical architecture via NH⋯O, CH⋯O hydrogen bonding and π–π interactions. [ABSTRACT FROM AUTHOR]

Infections from antimicrobial resistant pathogens have been considered as lethal threats to human health if antibiotic treatments become ineffective. Antimicrobial peptides (AMPs) show broad‐spectrum antimicrobial activity against resistant strains via a membrane disruptive mechanism without developing further resistance and are promising candidates to combat resistant microbes. However, currently developed small molecular AMPs are limited by weak antimicrobial efficacy and potential cytotoxicity. Herein, an antimicrobial AMP hydrogel based on supramolecular self‐assembly is developed. The hydrogel shows strong antimicrobial activity and high potency against antimicrobial resistant microbes. It also possesses high cytocompatibility and immunoregulative activity. The synergistic effects lead to its significant healing of the skin abscess disease induced by the methicillin‐resistant Staphylococcus aureus infection. This study not only sheds light on the design strategies and immune‐related antimicrobial actions of supramolecular AMP hydrogels, but also advances the development of self‐assembly peptide platform to fight against antimicrobial resistant infections. [ABSTRACT FROM AUTHOR]

Organoids are an emerging technology with great potential in human disease modelling, drug development, diagnosis, tissue engineering, and regenerative medicine. Organoids as 3D-tissue culture systems have gained special attention in the past decades due to their ability to faithfully recapitulate the complexity of organ-specific tissues. Despite considerable successes in culturing physiologically relevant organoids, their real-life applications are currently limited by challenges such as scarcity of an appropriate biomimetic matrix. Peptide amphiphiles (PAs) due to their well-defined chemistry, tunable bioactivity, and extracellular matrix (ECM)-like nanofibrous architecture represent an attractive material scaffold for organoids development. Using cerebral organoids (COs) as exemplar, we demonstrate the possibility to create bio-instructive hydrogels with tunable stiffness ranging from 0.69 kPa to 2.24 kPa to culture and induce COs growth. We used orthogonal chemistry involving oxidative coupling and supramolecular interactions to create two-component hydrogels integrating the bio-instructive activity and ECM-like nanofibrous architecture of a laminin-mimetic PAs (IKVAV-PA) and tunable crosslinking density of hyaluronic acid functionalized with tyramine (HA-Try). Multi-omics technology including transcriptomics, proteomics, and metabolomics reveals the induction and growth of COs in soft HA-Tyr hydrogels containing PA-IKVAV such that the COs display morphology and biomolecular signatures similar to those grown in Matrigel scaffolds. Our materials hold great promise as a safe synthetic ECM for COs induction and growth. Our approach represents a well-defined alternative to animal-derived matrices for the culture of COs and might expand the applicability of organoids in basic and clinical research. Synthetic bio-instructive materials which display tissue-specific functionality and nanoscale architecture of the native extracellular matrix are attractive matrices for organoids development. These synthetic matrices are chemically defined and animal-free compared to current gold standard matrices such as Matrigel. Here, we developed hydrogel matrices with tunable stiffness, which incorporate laminin-mimetic peptide amphiphiles to grow and expand cerebral organoids. Using multi-omics tools, the present study provides exciting data on the effects of neuro-inductive cues on the biomolecular profiles of brain organoids. [Display omitted] [ABSTRACT FROM AUTHOR]

Peptide‐ and polypeptide‐based self‐assembling gene delivery systems have received considerable attention owing to their inherent biocompatibility and bioactivity. Gene carriers based on elastin‐like polypeptides (ELPs) have been extensively studied because of their controllability and unique temperature responsiveness. The (EK)10‐PLGLAG‐Tat polypeptide sequence was selected for tumor gene delivery, with ELP serving as the hydrophobic core. In this sequence, a hydration layer can be formed on the surface of the carrier using the zwitterionic peptide segment (EK)10, which helps prevent the nonspecific adsorption of plasma proteins. Additionally, the MMP‐2 enzyme‐responsive PLGLAG peptide segment is responsible for exposing the cell‐penetrating peptide Tat specifically near tumor cells, facilitating the penetration of tumor cells. To introduce (EK)10‐PLGLAG‐Tat into the self‐assembling carrier while ensuring its bioactivity, a leucine zipper ZR/ZE with opposite charges was used to link it to the ELP. Because of its high specificity and low systemic toxicity, the carrier was named environmentally responsive gene carrier (ERGV). Experimental results demonstrated that the ERGV effectively removed (EK)10 in MMP‐2 overexpressed environments, altering the surface charge from negative to positive and facilitating ssDNA delivery into tumor cells. These findings highlight the potential of ERGVs as a safe and efficient method for targeted gene delivery to tumors. [ABSTRACT FROM AUTHOR]

Redox–enzyme‐mediated electrochemical processes such as hydrogen production, nitrogen fixation, and CO2 reduction are at the forefront of the green chemistry revolution. To scale up, the inefficient two‐dimensional (2D) immobilization of redox enzymes on working electrodes must be replaced by an efficient dense 3D system. Fabrication of 3D electrodes was demonstrated by embedding enzymes in polymer matrices. However, several requirements, such as simple immobilization, prolonged stability, and resistance to enzyme leakage, still need to be addressed. The study presented here aims to overcome these gaps by immobilizing enzymes in a supramolecular hydrogel formed by the self‐assembly of the peptide hydrogelator fluorenylmethyloxycarbonyl‐diphenylalanine. Harnessing the self‐assembly process avoids the need for tedious and potentially harmful chemistry, allowing the rapid loading of enzymes on a 3D electrode under mild conditions. Using the [FeFe] hydrogenase enzyme, high enzyme loads, prolonged resistance against electrophoresis, and highly efficient hydrogen production are demonstrated. Further, this enzyme retention is shown to arise from its interaction with the peptide nanofibrils. Finally, this method is successfully used to retain other redox enzymes, paving the way for a variety of enzyme‐mediated electrochemical applications. [ABSTRACT FROM AUTHOR]

Background: Protein purification remains a critical need for biosciences and biotechnology. It frequently requires multiple rounds of chromatographic steps that are expensive and time-consuming. Our lab previously reported a cleavable self-aggregating tag (cSAT) scheme for streamlined protein expression and purification. The tag consists of a self-assembling peptide (SAP) and a controllable self-cleaving intein. The SAP drives the target protein into an active aggregate, then by intein-mediated cleavage, the target protein is released. Here we report a novel cSAT scheme in which the self-assembling peptide is replaced with a salt inducible self-assembling peptide. This allows a target protein to be expressed first in the soluble form, and the addition of salt then drives the target protein into the aggregated form, followed by cleavage and release. Results: In this study, we used MpA (MKQLEDKIEELLSKAAMKQLEDKIEELLSK) as a second class of self-assembling peptide in the cSAT scheme. This scheme utilizes low salt concentration to keep the fusion protein soluble, while eliminating insoluble cellular matters by centrifugation. Salt then triggers MpA-mediated self-aggregation of the fusion, removing soluble background host cell proteins. Finally, intein-mediated cleavage releases the target protein into solution. As a proof-of-concept, we successfully purified four proteins and peptides (human growth hormone, 22.1 kDa; LCB3, 7.7 kDa; SpyCatcherΔN-ELP-SpyCatcherΔN, 26.2 kDa; and xylanase, 45.3 kDa) with yields ranging from 12 to 87 mg/L. This was comparable to the classical His-tag method both in yield and purity (72–97%), but without the His-tag. By using a further two-step column purification process that included ion-exchange chromatography and size-exclusion chromatography, the purity was increased to over 99%. Conclusion: Our results demonstrate that a salt-inducible self-assembling peptide can serve as a controllable aggregating tag, which might be advantageous in applications where soluble expression of the target protein is preferred. This work also demonstrates the potential and advantages of utilizing salt inducible self-assembling peptides for protein separation. [ABSTRACT FROM AUTHOR]

De novo designed peptides that self-assemble into cross-β rich fibrillar biomaterials have been pursued as an innovative platform for the development of adjuvant- and inflammation-free vaccines. However, they share structural and morphological properties similar to amyloid species implicated in neurodegenerative diseases, which has been a long-standing concern for their successful translation. Here, we comprehensively characterize the amyloidogenic character of the amphipathic self-assembling cross-β peptide KFE 8 , compared to pathological amyloid and amyloid-like proteins α-synuclein (α-syn) and TDP-43. Further, we developed plasmid-based DNA vaccines with the KFE 8 backbone serving as a scaffold for delivery of a GFP model antigen. We find that expression of tandem repeats of KFE 8 is non-toxic and efficiently cleared by autophagy. We also demonstrate that preformed KFE 8 fibrils do not cross-seed amyloid formation of α-syn in mammalian cells compared to α-syn preformed fibrils. In mice, vaccination with plasmids encoding the KFE 32 -GFP fusion protein elicited robust immune responses, inducing production of significantly higher levels of anti-GFP antibodies compared to soluble GFP. Antigen-specific CD8+T cells were also detected in the spleens of vaccinated mice and cytokine profiles from antigen recall assays indicate a balanced Th1/Th2 response. These findings illustrate that cross-β-rich peptide nanofibers have distinct physicochemical properties from those of pathological amyloidogenic proteins, and are an attractive platform for the development of DNA vaccines with self-adjuvanting properties and improved safety profiles. Biomaterials comprised of self-assembling peptides hold great promise for the development of new vaccines that do not require use of adjuvants. However, these materials have safety concerns, as they self-assemble into cross-β rich fibrils that are structurally similar to amyloid species implicated in disease. Here, we comprehensively study the properties of these biomaterials. We demonstrate that they have distinct properties from pathological proteins. They are non-toxic and do not trigger amyloidogenesis. Vaccination of these materials in mice elicited a robust immune response. Most excitingly, our work suggests that this platform could be used to develop DNA-based vaccines, which have few storage requirements. Further, due to their genetic encoding, longer sequences can be generated and the vaccines will be amenable to modification. [Display omitted] [ABSTRACT FROM AUTHOR]

Although the relationship between molecular and supramolecular chirality remains elusive, the existing results have demonstrated the vital role of hydrophilic motifs in controlling the supramolecular handedness of peptide nanofibrils compared with hydrophobic ones. However, unlike conventional hydrophobic residues, we speculate that aromatic hydrophobic residues are mostly likely to play a unique role in regulating the supramolecular handedness because the π−π stacking interactions of their side chains are directional like hydrogen bonding and can direct high levels of self-assembly due to the geometric confining of aromatic rings. To confirm this hypothesis, we here design a series of amphiphilic short peptides, with their hydrophobic motifs being composed of aromatic residues. Their short lengths not only favor their structural stability, synthesis, and sequence variation but also enable us to readily link their molecular and supramolecular structures. Through the combination of experiments and theoretical simulations, we demonstrate that the peptides containing L-form aromatic residues form left-handed nanofibrils while those containing D-form aromatic residues assemble into right-handed ones, irrespective of the chirality of their C-terminal hydrophilic residue. Theoretical calculations revealed that the stacking of aromatic side chains between β-strands directed the twisting direction of the β-sheets formed, with L- and D-form phenylalanine side chains stacking in a clockwise and anti-clockwise way, and more ordered and stronger aromatic stacking for homochiral peptides facilitated the formation of nanofibrils with a marked tubular feature. This study has bridged the knowledge gap in our understanding of how aromatic residues affect the supramolecular chirality of short peptides. [ABSTRACT FROM AUTHOR]

We investigate the effect of mobile polymer brushes on proteins embedded in biological membranes by employing both Asakura–Oosawa type of theoretical model and coarse-grained molecular dynamics simulations. The brush polymer-induced depletion attraction between proteins changes non-monotonically with the size of brush. The depletion interaction, which is determined by the ratio of the protein size to the grafting distance between brush polymers, increases linearly with the brush size as long as the polymer brush height is shorter than the protein size. When the brush height exceeds the protein size, however, the depletion attraction among proteins is slightly reduced. We also explore the possibility of the brush polymer-induced assembly of a large protein cluster, which can be related to one of many molecular mechanisms underlying recent experimental observations of integrin nanocluster formation and signaling. [ABSTRACT FROM AUTHOR]