A minimal length rigid helical peptide motif allows rational design of modular surfactants

Abstract

Extensive work has been invested in the design of bio-inspired peptide emulsifiers. Yet, none of the formulated surfactants were based on the utilization of the robust conformation and self-assembly tendencies presented by the hydrophobins, which exhibited highest surface activity among all known proteins. Here we show that a minimalist design scheme could be employed to fabricate rigid helical peptides to mimic the rigid conformation and the helical amphipathic organization. These designer building blocks, containing natural non-coded α-aminoisobutyric acid (Aib), form superhelical assemblies as confirmed by crystallography and microscopy. The peptide sequence is amenable to structural modularity and provides the highest stable emulsions reported so far for peptide and protein emulsifiers. Moreover, we establish the ability of short peptides to perform the dual functions of emulsifiers and thickeners, a feature that typically requires synergistic effects of surfactants and polysaccharides. This work provides a different paradigm for the molecular engineering of bioemulsifiers.

Redox‐Active Peptide‐Functionalized Quinquethiophene‐Based Electrochromic π‐Gel

“…The significant shifto fa mide Ib and from 1653 cm À1 to 1660 cm À1 supportsaconformationalc hange from unordered structuret os upramolecular helical structure by peptidic segment during self-assembly in the gel matrix. [68] This characteristic observation is also corroborated with CD spectroscopy.C ircular dichroism( CD) was used to scrutinise the supramolecular-aggregation preferences of self-assembled compound 1. Hydrogel of compound 1 shows strong CD absorption bands in the range of 350-550 nm primarily with ab isignated Cotton effect (Figure 2c).…”

“…The corresponding bands of compound 1 shifted to 1660 cm −1 , 1633 cm −1 and 1546 cm −1 in the hydrogel state. The significant shift of amide I band from 1653 cm −1 to 1660 cm −1 supports a conformational change from unordered structure to supramolecular helical structure by peptidic segment during self‐assembly in the gel matrix . This characteristic observation is also corroborated with CD spectroscopy.…”

From self‐assembled peptide‐ynes to peptide polyacetylenes and polydiacetylenes

“…The presence of a propargyl unit at the C‐terminus of 2 ‐ 4 allowed us to investigate for the first time formation of peptide‐based polyacetylene ( PAs ) and polydiacetylene ( PdAs ) organogels. According with the schematic representation reported in Figure , both PA and PdA backbones are able to template formation of parallelly oriented β‐sheet structures within their respective polymeric systems, thanks to the onset of geometrically perfect repetitions of highly conjugated double and double‐triple bonds, respectively . We are currently exploring the limits (dictated by the negative steric hindrance) and potentialities (governed by the positive template effect of well‐ordered networks) of the organogel‐forming peptide‐acetylene hybrid compounds for a further development of this fascinating opto‐electronic‐active, stimuli‐responsive, peptide‐based, polymer field …”

A Natural Triterpene Saponin‐Based Pickering Emulsion

“…Commercial pesticides like emulsifiable concentrates (ECs) and microemulsions (MEs) normally contain substantial amounts of surfactants and organic solvents, which cause serious environmental damage . In recent years, Pickering emulsions, which are stabilized by nano‐ or microscale particles instead of small‐molecule surfactants, have attracted immense attention . The particles adsorbed at the interface between two phases endow the emulsion system with ultrastability, biocompatibility, and adjustable permeability .…”

“…[4,5] In recent years, Pickering emulsions,w hich are stabilized by nano-or microscale particles insteado fs mall-molecule surfactants, have attracted immense attention. [6][7][8] The particles adsorbed at the interface betweent wo phases endow the emulsion system with ultrastability,b iocompatibility,a nd adjustable permeability. [9,10] To date, the particlesu sed for Pickering emulsions have mainly included silica, alumina, titanium oxides, clay,polysaccharides, and bio-nanoparticles.…”