Self-assembling short peptide amphiphiles as versatile delivery agents: a new frontier in antibacterial research

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.

Shape control of Au nanostructures using peptides for biotechnological applications

Metallic gold (Au) nanostructures have attracted attentions in various fields of materials science and electrical science in terms of catalysts, sensing systems, photonic devices, and drug delivery systems because of their characteristic physical, chemical, and biocompatible properties. Recently, Au nanostructures with near-infrared light absorbing properties have shown potential for applications such as biological imaging and thermotherapy in biotechnological fields. However, fabrication of Au nanostructures with complex shapes often requires the use of highly biotoxic substances such as surfactants and reducing agents. Peptides are promising compounds for controlling the shape of Au nanostructures by mineralization with several advantages for this purpose. In this highlight, we focus on the shapes with respect to the fabrication of Au nanostructures using biocompatible peptides. We classify the peptides that form Au nanostructures into three broad categories: those that bind Au ions, those that reduce Au ions, and those that control the direction of Au crystal growth. Then, we briefly summarize the correlations between peptide sequences and their roles, and propose future strategies for fabricating Au nanostructures using peptides for biotechnological applications.

Lipopeptides as tools in catalysis, supramolecular, materials and medicinal chemistry

Lipopeptides are amphiphilic peptides in which an aliphatic chain is attached to either the C or N terminus of peptides. Their self-assembly - into micelles, vesicles, nanotubes, fibres or nanobelts - leads to applications in nanotechnology, catalysis or medicinal chemistry. Self-organization of lipopeptides is dependent on both the length of the lipid tail and the amino acid sequence, in which the chirality of the peptide sequence can be transmitted into the supramolecular species. This Review describes the use of lipopeptides to design synthetic advanced dynamic supramolecular systems, nanostructured materials or self-responsive delivery systems in the area of medical biotechnology. We examine the influence of external stimuli, the ability of lipopeptide-derived structures to adapt over time and their application as medicinal agents with antibacterial, antifungal, antiviral or anticancer activities. Finally, we discuss the catalytic efficiency of lipopeptides, with the aim of building minimal synthetic enzymes, and recent efforts to incorporate metals into lipopeptide assemblies.

Short peptide amphiphile nanostructures facilitate sunlight-induced nanowelding of gold nanosheets

An effortless thermoplasmonic welding of multi-shaped gold nanosheets is achieved by ordinary and simple sunlight irradiation. A light-matter interaction occurred via the nanogaps of smaller nanosheets, leading to the enhancement of the electromagnetic field and thus effectively concentrating the heat at the welding point. The sPA peptide nanostructure facilitates the nanowelding of small caged gold nanostructures.

Role of gold nanoparticles in advanced biomedical applications

Gold nanoparticles (GNPs) have generated keen interest among researchers in recent years due to their excellent physicochemical properties. In general, GNPs are biocompatible, amenable to desired functionalization, non-corroding, and exhibit size and shape dependent optical and electronic properties. These excellent properties of GNPs exhibit their tremendous potential for use in diverse biomedical applications. Herein, we have evaluated the recent advancements of GNPs to highlight their exceptional potential in the biomedical field. Special focus has been given to emerging biomedical applications including bio-imaging, site specific drug/gene delivery, nano-sensing, diagnostics, photon induced therapeutics, and theranostics. We have also elaborated on the basics, presented a historical preview, and discussed the synthesis strategies, functionalization methods, stabilization techniques, and key properties of GNPs. Lastly, we have concluded this article with key findings and unaddressed challenges. Overall, this review is a complete package to understand the importance and achievements of GNPs in the biomedical field.

Self-assembly of a Sequence-shuffled Short Peptide Amphiphile Triggered by Metal Ions into Terraced Nanodome-like Structures

We highlight the structural diversity of strategically designed two short peptide amphiphiles (sPAs) and describe their structure-function relationship studies. The shuffling of two key amino acids, that is, tyrosine and phenylalanine, in a designed sPA lead to a pair of constitutional isomers. Such small and strategic alteration can bring a substantial change in the self-assembling pattern. Inspired from the naturally occurring metallopeptides, bioactive transition-metal ions were used for constructing the unusual nanostructures. Use of appropriate metal ions created bigger differences between the properties of these isomers and hence the self-assembly. Coordination of appropriate transition metal ions modifies the internal nanoscale structures of sPA, thus leading to the formation of vertically stacked terraced layers with decreasing size, which possess a high degree of dimensional regularity. We propose that such metal-induced terraced nanodome-like hierarchical self-assembly may have relevance for specific biotechnology applications.

Transition metal ions induced secondary structural transformation in a hydrophobized short peptide amphiphile

Transition metal ions mediate the secondary structural transformation of hydrophobized sPA and can be applied to the design and development of stimuli-responsive nanomaterials.

Transition Metal Ion-Mediated Tyrosine-Based Short-Peptide Amphiphile Nanostructures Inhibit Bacterial Growth

We report the design and synthesis of a biocompatible small-peptide-based compound for the controlled and targeted delivery of encapsulated bioactive metal ions through transformation of the internal nanostructures of its complexes. A tyrosine-based short-peptide amphiphile (sPA) was synthesized and observed to self-assemble into β-sheet-like secondary structures. The self-assembly of the designed sPA was modulated by application of different bioactive transition-metal ions, as was confirmed by spectroscopic and microscopic techniques. These bioactive metal-ion-conjugated sPA hybrid structures were further used to develop antibacterial materials. As a result of the excellent antibacterial activity of zinc ions the growth of clinically relevant bacteria such as Escherichia coli was inhibited in the presence of zinc⋅sPA conjugate. Bacterial testing demonstrated that, due to high biocompatibility with bacterial cells, the designed sPA acted as a metal ion delivery agent and might therefore show great potential in locally addressing bacterial infections.

Biotin–avidin interaction triggers conversion of triskelion peptide nanotori into nanochains

Triskelion biotinylated peptide is self-assembled into nanotorus structures followed by dimerization and chain formation in the presence of avidin.