Self-assembled peptide and protein amyloid nanostructures have traditionally been considered only as pathological aggregates implicated in human neurodegenerative diseases. In more recent times, these nanostructures have found interesting applications as advanced materials in biomedicine, tissue engineering, renewable energy, environmental science, nanotechnology and material science, to name only a few fields. In all these applications, the final function depends on: (i) the specific mechanisms of protein aggregation, (ii) the hierarchical structure of the protein and peptide amyloids from the atomistic to mesoscopic length scales and (iii) the physical properties of the amyloids in the context of their surrounding environment (biological or artificial). In this review, we will discuss recent progress made in the field of functional and artificial amyloids and highlight connections between protein/peptide folding, unfolding and aggregation mechanisms, with the resulting amyloid structure and functionality. We also highlight current advances in the design and synthesis of amyloid-based biological and functional materials and identify new potential fields in which amyloid-based structures promise new breakthroughs.

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Self-assembling peptide and protein amyloids: from structure to tailored function in nanotechnology

The aggregation of proteins is central to many aspects of daily life, including food processing, blood coagulation, eye cataract formation disease and prion-related neurodegenerative infections(1-5). However, the physical mechanisms responsible for amyloidosis-the irreversible fibril formation of various proteins that is linked to disorders such as Alzheimer's, Creutzfeldt-Jakob and Huntington's diseases-have not yet been fully elucidated(6-9). Here, we show that different stages of amyloid aggregation can be examined by performing a statistical polymer physics analysis of single-molecule atomic force microscopy images of heat-denatured beta-lactoglobulin fibrils. The atomic force microscopy analysis, supported by theoretical arguments, reveals that the fibrils have a multistranded helical shape with twisted ribbon-like structures. Our results also indicate a possible general model for amyloid fibril assembly and illustrate the potential of this approach for investigating fibrillar systems.

/pdf/understanding-amyloid-aggregation-by-statistical-analysis-of-4pmbr699qb.pdf

Understanding amyloid aggregation by statistical analysis of atomic force microscopy images

β-Lactoglobulin and WPI aggregates: Formation, structure and applications

The aggregation of proteins is of fundamental relevance in a number of daily phenomena, as important and diverse as blood coagulation, medical diseases, or cooking an egg in the kitchen. Colloidal food systems, in particular, are examples that have great significance for protein aggregation, not only for their importance and implications, which touches on everyday life, but also because they allow the limits of the colloidal science analogy to be tested in a much broader window of conditions, such as pH, ionic strength, concentration and temperature. Thus, studying the aggregation and self-assembly of proteins in foods challenges our understanding of these complex systems from both the molecular and statistical physics perspectives. Last but not least, food offers a unique playground to study the aggregation of proteins in three, two and one dimensions, that is to say, in the bulk, at air/water and oil/water interfaces and in protein fibrillation phenomena. In this review we will tackle this very ambitious task in order to discuss the current understanding of protein aggregation in the framework of foods, which is possibly one of the broadest contexts, yet is of tremendous daily relevance.

http://iopscience.iop.org/article/10.1088/0034-4885/76/4/046601/pdf

The self-assembly, aggregation and phase transitions of food protein systems in one, two and three dimensions

Industrial development, energy production and mining have led to dramatically increased levels of environmental pollutants such as heavy metal ions, metal cyanides and nuclear waste. Current technologies for purifying contaminated waters are typically expensive and ion specific, and there is therefore a significant need for new approaches. Here, we report inexpensive hybrid membranes made from protein amyloid fibrils and activated porous carbon that can be used to remove heavy metal ions and radioactive waste from water. During filtration, the concentration of heavy metal ions drops by three to five orders of magnitude per passage and the process can be repeated numerous times. Notably, their efficiency remains unaltered when filtering several ions simultaneously. The performance of the membrane is enabled by the ability of the amyloids to selectively absorb heavy metal pollutants from solutions. We also show that our membranes can be used to recycle valuable heavy metal contaminants by thermally reducing ions trapped in saturated membranes, leading to the creation of elemental metal nanoparticles and films.

Amyloid–carbon hybrid membranes for universal water purification

https://doc.rero.ch/record/10758/files/mezzenga_shi.pdf

Structure of Heat-Induced β-Lactoglobulin Aggregates and their Complexes with Sodium-Dodecyl Sulfate

The present invention relates to whey protein micelles, particularly to whey protein micelle concentrates or powders thereof and to a method for producing them. The present invention also pertains to the use of these micelles concentrates or powders thereof in nutrition and/or cosmetics and/or pharmaceutics.

Whey protein micelles

https://www.cell.com/biophysj/pdf/S0006-3495(08)03227-X.pdf

Oleoylethanolamide-Based Lyotropic Liquid Crystals as Vehicles for Delivery of Amino Acids in Aqueous Environment

Oil-in-water and water-in-oil capsules, and flat membranes of tuneable thickness and composition were prepared in one single facile step, based on the interfacial complexation between chitosan and anionic phosphatidic fatty acids. The phosphatidic acid molecules were introduced via the oil phase. The thickness of the capsule shell or the membrane grows by a diffusion-controlled mechanism, hence can be tuned using e.g. concentration and formation time parameters. A mechanism is proposed to explain the observed behavior. The capsule size is set by the emulsification conditions applied. Microfluidic methods proved useful for the generation of hollow capsules of uniform size and thickness in one step. The capsules and membranes display remarkable integrity over several years in a pH window 2–14. The thickness can easily reach several micrometres within an hour for the wet capsule shell or membrane, which explains the high interfacial rheological properties measured. Hence various processes can be envisaged after their formation. The simple preparation opens the way to tailored, environment-responsive composite systems for fabricating biopolymer-based materials for various applications. The capsules could be washed from the surrounding continuous phase and placed into one of arbitrary choice. Furthermore, the surface of the w/o capsules and of the membranes could be decorated by particles that attach to the water/oil interface with a high energy. The choice of the particle functionality is left open.

Matthieu Pouzot

Papers

Structure of Heat-Induced β-Lactoglobulin Aggregates and their Complexes with Sodium-Dodecyl Sulfate

Whey protein micelles

Oleoylethanolamide-Based Lyotropic Liquid Crystals as Vehicles for Delivery of Amino Acids in Aqueous Environment

Tuneable thickness barriers for composite o/w and w/o capsules, films, and their decoration with particles

Influence of blend ratio and water content on the rheology and fragility of maltopolymer/maltose blends