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A single amino acid in a peptide sequence can play an important role to tune the self‐assembly and hydrogelation behaviour. Here, a C‐terminal cysteine‐containing ultrashort peptide hydrogelator forms hydrogel through non‐covalent and covalent interactions. Interestingly, the hydrogel is insoluble in water and buffer solutions at different pH values (1‐13) and is thixotropic and injectable. In recent years, removing dyes from contaminated water has become a significant concern because of the shortage of freshwater resources. Therefore, the adsorption of dyes through a reliable, straightforward, nontoxic, cheap, and environmentally friendly adsorbent has become a popular topic. Hence, the hydrogelator was exploited to remove organic dyes from wastewater, harnessing its applicability in the gel phase and solid supports (filter paper and cotton). [ABSTRACT FROM AUTHOR]

The alteration of amino acid register in peptides could affect their folding properties and thus functions. The effect of sequence in metal ion induced folding of peptide/protein is important in the design of new functional protein structures, such as biomimetics. In this paper, a set of hairpin peptides with identical composition but different histidine locations have been designed to exploit the metal ion‐mediated peptide intramolecular folding transformation through the adjustment of histidine and lysine residue locations. The results demonstrated that the histidine positions in peptide sequence could dramatically affect the coordination modes between peptides and Cu(II) ion. The Cu(II) coordination could affect the secondary structure transformation and self‐assembly along with electrostatic interaction and hydrogen bonding synergistically. Three molecules with VHVH sequence at each side of the turn segment (VDPPT) were apt to coordinate with Cu(II) ion with three or four histidines. The closer the VHVH motifs were to the turn segment, the more easier the molecules were to form β sheet structure with the promotion of Cu(II) ions. These results demonstrated that the purposeful location of key amino acids in peptides could achieve the controllable conformation transformation of hairpin peptides, which provides useful strategies for biomimetic design, such as metalloenzymes. [ABSTRACT FROM AUTHOR]

A heating treatment method for the synthesis of fluorescent nanoparticles using simple N-(9-fluorenylmethoxycarbonyl) (Fmoc)-protected tripeptides is reported. Two pairs of Fmocprotected tripeptides (Fmoc FR1R2, R1=F or W, R2=H or Y) were designed by changing the amino acid sequences of the peptides. The peptides can self-assemble into nanofibers at lower temperatures, which will spontaneously transform into fluorescent nanoparticles under heating treatment. Moreover, the fluorescence properties of the self-assembled structures can be affected by changing amino acids in the middle of the tripeptide. Specifically, tryptophan (W) can promote fluorescence of the assemblies incubated at high temperatures. Thus, the temperatures and amino sequences of the Fmocprotected tripeptides have significant effects on the fluorescence of the assembled nanostructures. The results provide a design principle for self-assembled fluorescent peptide nanostructures with potential biomedical applications. [ABSTRACT FROM AUTHOR]

Nucleic acids play a pivotal role in life processes. The endeavours to shed light on the essential properties of these intriguing building blocks led us to the synthesis of different analogues and the investigation of their properties. First various peptide nucleic acid monomers and oligomers have been synthesized, using an Fmoc/acyl protecting group strategy, and their properties studied. The serendipitous discovery of a side reaction of coupling agents led us to the elaboration of a peptide sequencing method. The capricious behaviour of guanine derivatives spurred the determination of their substitution pattern using 13C, 15N NMR, and mass spectrometric methods. The properties of guanines initiated the logical transition to the study of supramolecular systems composed of purine analogues. Thus, xanthine and uracil derivatives have been obtained and their supramolecular self‐assembly properties scrutinized in gas, solid, and liquid states and at solid‐liquid interfaces. [ABSTRACT FROM AUTHOR]

Although chiral nanostructures have been fabricated at various structural levels, the transfer and amplification of chirality from molecules to supramolecular self‐assemblies are still puzzling, especially for heterochiral molecules. Herein, four series of C2‐symmetrical dipeptide‐based derivatives bearing various amino acid sequences and different chiralities are designed and synthesized. The transcription and amplification of molecular chirality to supramolecular assemblies are achieved. The results show that supramolecular chirality is only determined by the amino acid adjacent to the benzene core, irrespective of the absolute configuration of the C‐terminal amino acid. In addition, molecular chirality also has a significant influence on the gelation behavior. For the diphenylalanine‐based gelators, the homochiral gelators can be gelled through a conventional heating–cooling process, whereas heterochiral gelators form translucent stable gels under sonication. The racemic gels possess higher mechanical properties than those of the pure enantiomers. All of these results contribute to an increasing knowledge over control of the generation of specific chiral supramolecular structures and the development of new optimized strategies to achieve functional supramolecular organogels through heterochiral and racemic systems. [ABSTRACT FROM AUTHOR]

The rational design of self‐assembling organic materials is extremely challenging due to the difficulty in precisely predicting solid‐state architectures from first principles, especially if synthons are conformationally flexible. A tractable model system to study self‐assembly was constructed by appending cyclopropanoyl caps to the N termini of helical α/β‐peptide foldamers, designed to form both N−H⋅⋅⋅O and Cα−H⋅⋅⋅O hydrogen bonds, which then rapidly self‐assembled to form foldectures (foldamer architectures). Through a combined analytical and computational investigation, cyclopropanoyl capping was observed to markedly enhance self‐assembly in recalcitrant substrates and direct the formation of a single intermolecular N−H⋅⋅⋅O/Cα−H⋅⋅⋅O bonding motif in single crystals, regardless of peptide sequence or foldamer conformation. In contrast to previous studies, foldamer constituents of single crystals and foldectures assumed different secondary structures and different molecular packing modes, despite a conserved N−H⋅⋅⋅O/Cα−H⋅⋅⋅O bonding motif. DFT calculations validated the experimental results by showing that the N−H⋅⋅⋅O/Cα−H⋅⋅⋅O interaction created by the cap was sufficiently attractive to influence self‐assembly. This versatile strategy to harness secondary noncovalent interactions in the rational design of self‐assembling organic materials will allow for the exploration of new substrates and speed up the development of novel applications within this increasingly important class of materials. Premeditated bonding: A model system to study self‐assembly was constructed by appending cyclopropanoyl caps to the N termini of helical α/β‐peptide foldamers, which were designed to form hydrogen bonds and then rapidly self‐assemble into foldectures (see figure). DFT calculations validated the experimental results by showing that the N−H⋅⋅⋅O/Cα−H⋅⋅⋅O interaction was sufficiently attractive to influence self‐assembly. [ABSTRACT FROM AUTHOR]

Infections caused by Staphylococcal and Micrococcal species represent a major public health burden. Although treatments do exist, these tend to be associated with cytotoxic effects; furthermore, the emergence of antimicrobial resistance presents an immediate challenge. New classes of active compounds are required to address these threats to human health. Here we present a de novo peptidomimetic strategy that produces self‐assembling cationic antimicrobials. To identify a candidate compound with bactericidal activity, a small library of 8 peptidomimetics comprising ultrashort peptide sequences attached to a 3,5‐diaminobenzoic acid scaffold was generated and tested against Micrococcus luteus and Staphylococcus aureus. Self‐assembly appears to be the driving force for increased potency, likely by contributing to increased local surface charge density and peptide mass and producing a multivalent effect that enhances electrostatic interactions with negatively charged bacterial membranes, causing membrane disruption. The most active library member C7 forms patched micellar nanoparticles and has an activity higher than that of known natural antimicrobial peptides against M luteus. C7 also shows activity comparable to that of gramicidin S and the standard antibiotic vancomycin used in antibacterial therapy, but with a greater selectivity index. Importantly, C7 is also nontoxic and nonhemolytic, unlike the currently administered vancomycin, which can cause acute renal failure, and gramicidin S, which is highly hemolytic in nature. The short sequence length, ease of design, convenient synthesis strategy, and presence of a substitutable hydrophobic residue that enables self‐assembly into different nanostructures make this model compound highly attractive for generating cost‐effective, rapid‐acting peptide‐based antimicrobials. [ABSTRACT FROM AUTHOR]