Co-assembly, spatiotemporal control and morphogenesis of a hybrid protein–peptide system

Abstract

ature uses self-assembly to create a widespread variety of complex structures with elaborate geometries and outstanding properties 1 such as hierarchical order, adaptability, selfhealing and bioactivity. Developing new bioinspired processes based on dynamic self-assembly could facilitate the fabrication of synthetic three-dimensional (3D) materials with enhanced complexity, dynamic properties and functionality 2 . Proteins are particularly attractive building blocks because of their versatility and biofunctionality 3 . Elastin-like polypeptides (ELPs) 4 are recombinant proteins that have generated great interest 5 as a result of their modular structure, bioactivity, ease of design and production, and the possibility to create robust and elastic materials 5,6 . ELPs allow for a tunable molecular design 7 and are based on the tropoelastin recurrent motif Val-Pro-Gly-X-Gly (VPGXG), in which X is any amino acid other than proline 7 . This repeating pentapeptide provides ELPs with a thermoresponsive behaviour. Below a critical transition temperature (T t ), the ELP molecule undergoes a reversible-phase transition wherein the protein is soluble in aqueous solution and becomes highly solvated, surrounded by clatharate-like water structures. Above the T t , the hydrophobic domains dehydrate and the protein chain hydrophobically collapses and aggregates to form a phaseseparated state 8 .The use of natural and synthetic proteins to create functional materials has been hindered by the difficulty in controlling their conformation and nanoscale assembly with the precision required to form macroscopic materials. This limitation has driven the development of simpler and more-predictable peptide-based materials 9,10 . Peptide amphiphiles (PAs), for example, are synthetic molecules that can self-assemble into nanofibres and create functional 3D hydrogels that emulate the fibrous architecture of the extracellular matrix (ECM) 11,12 . Nonetheless, most peptide and/or protein materials are formed through equilibrium-based self-assembly approaches that are capable of generating stable supramolecular structures, but with limited hierarchy and spatiotemporal control, which has hindered their functionality 2 .Novel approaches based on the dynamic self-assembly of inorganic building blocks [13][14][15] , actin self-organization 16 and the combination of top-down processes with peptide self-assembly have been reported recently 17 . In particular, Stupp and co-workers have described a self-assembling membrane system obtained through strong electrostatic interactions between PAs and oppositely charged polysaccharides 18 . However, the possibility to exploit the unique structural and functional properties of proteins to create dynamic hierarchical materials remains an elusive target. In this study, we attempt to overcome this hurdle by using self-assembling peptides to promote protein conformational changes and guide their assembly into complex, yet functional, materials. We report the discovery and development of a protein/peptide system t...

Electrostatic self-assembly of polysaccharides into nanofibers

“…Zeta potential ( ) measurements confirmed that both components xanthan and chitosan oligomers have opposite charge and hence, they are able to co-assemble by electrostatic interactions. These type of interactions have been shown essential to drive the self-assembly of interfacial systems [2,5,30,31].…”

Cross-linking of a biopolymer-peptide co-assembling system

“…1A). This system relies on the conformational modification of the ELR molecules by interacting non-covalently (electrostatic and hydrophobic interactions) with the PA molecules [10]. While the membrane formed is stable in water, a weakening of the system is visible when immersed in ionic solutions (e.g.…”

“…In this study, we investigated possible exogenous cross-linking strategies (4S-StarPEG, SCM-PEG-SCM, GNP, and GTA) for the en [10]. (C) Turbidity profile showing the effect of ionic environments on the molecular interaction between ELR and PA after incubation in physiological environment at 4°C and 40°C, respectively.…”

“…*Denotes significant differences between the different groups at p < 0.05. hancement of stability and structural integrity of self-assembling systems with potential biomedical application. Specifically, we explored the performance of these cross-linkers in the biopolymer-peptide self-assembling system (ELR/PA membrane) previously reported by our group as ELP/PA system [10]. We compared cross-linking efficiency, resistance to enzymatic degradation, and potential toxicity of these cross-linkers, in order to identify an effective cross-linker agent that does not compromise hierarchical nano/microstructure and bioactive properties.…”

“…An increasing number of strategies aim to fabricate, through molecular self-assembly, hierarchical structures with precision and tuneability [1,3,[9][10][11][12]. Our group has recently reported a co-assembling system based on the conformational modification of elastin-like recombinamers (ELRs) by peptide amphiphiles (PAs) that enables the fabrication of membranes with the capacity to undergo morphogenesis into complex tubular micro/macro structures [10]. When a drop of PA is injected into a larger volume of ELP, an interfacial assembly spontaneously develops, forming a membrane that opens and adheres upon contact to any surface.…”