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.

This study demonstrates the beneficial role of di-tryptophan containing short peptide amphiphiles (sPA), for the synthesis and stabilization of AgNPs in the presence of sunlight followed by garlanding of AgNPs along the fibrous network of sPA. Such hybrid structures were precisely and selectively moulded into a nanowreath-type morphology due to the thermoplasmonic effect of AgNPs, and can be used for several bio-nanotechnological applications.

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

Engineering of nanomaterials for nanotechnological applications is always in high demand. In this work, we have designed four special classes of short peptide amphiphiles (sPA) consisting hydrophobic palmitoyl tail which is conjugated with ditryptophan unit followed by a nonaromatic acid(s). We observed that variation in head group of sPA according to the hydrophobicity scale provide variation in their self assembly too, therefore used for the engineering of the especial class of metal-organic nanohybrids. The sPA containing highly hydrophobic head exhibit vesicular morphology in organic and aqueous organic solvents and exposure of sunlight to the solution of sPA with Au(III) ions leads to the formation of multi-shaped AuNPs followed by encapsulation by sPA envelope. The purified gold colliod was further irradiated by continuous wave (CW) laser of 532 nm wavelength which leads to the conversion of multi-shaped AuNPs into uniform shape and size as confirmed by spectroscopic and microscopic investigations. Prolonged irradiation by laser, leads to the plasmonic welding of AuNPs which is mainly guided by sPA envelope produced, nanorods of submicron length. Such template guided laser induced engineering of AuNRs can show the potential applications in the field of nano-medicine, bio-nanotechnology and theranostics.

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