Sustainable Bioplastics from Amyloid Fibril-Biodegradable Polymer Blends

Abstract

Plastic waste production is a global challenging problem since its accumulation in the environment is causing devastating effects on the planet's ecosystem. Sustainable and green solutions are urgently needed, and this pairs with increasingly stronger regulations combined with improved ecological awareness. This study proposes a simple, scalable and water-based process to produce free-standing, transparent and flexible bioplastic films by combining amyloid fibrils with biodegradable polymers as two main building blocks. Amyloid fibrils can be obtained through denaturation and self-assembly from a broad class of food proteins found in milk, soy, and egg, for example. Whey is used here as a model protein, since it is the major by-product of dairy industries, and its valorization creates a valuable opportunity to produce sustainable, biodegradable, and environmentally friendly bioplastics perfectly integrated within a circular economy. Against this background, we highlight the sustainability superiority of these bioplastics over common plastics and bioplastic via a detailed life cycle assessment, anticipating an important role of this new class of bioplastics in mitigating the pressing plastic pollution challenge.

Strengthening and Toughening of Protein-Based Thermosets via Intermolecular Self-Assembly

“…CP120 possesses fracture stress of 11.3 ± 0.4 MPa, modulus of 85.9 ± 6.3 MPa, and toughness of 19.2 ± 1.4 MJ/m 3 , representing an increase of 48, 36, and 31%, respectively, compared to the thermoset CP23. Importantly, protein copolymers with intermolecular β-sheet structures have mechanical properties similar to those of tough protein materials ,,, and are comparable to or exceed those of bio-based polyurethanes. − Given the economic feasibility , and mechanical comparability, the developed copolymers could be a valuable alternative to bio-polyurethanes.…”

“…Plasticizers, such as glycerol and ethylene glycol, are often used to make protein materials easier to process and to provide extensibility and flexibility. ,− Surfactants can lower the melting point by disrupting molecular interactions, allowing proteins to be liquefied and processed in the absence of solvents. , However, plasticizers and surfactants sacrifice stiffness and strength and tend to absorb moisture, causing further reduction in mechanical properties. ,− Blending of proteins with soft polymers (polymers with low glass transition temperature T g ) can achieve extensibility and toughness without such dramatic sacrifices in strength and stiffness. Examples include proteins added to rubbers that can aggregate and form reinforcing networks and proteins or protein fibrils blended with poly­(vinyl alcohol) . Given that polymer blends frequently suffer from compatibility issues, copolymers would be promising candidates for the development of high-performance and stable thermosets …”

“…Examples include proteins added to rubbers that can aggregate and form reinforcing networks 19 and proteins or protein fibrils blended with poly(vinyl alcohol). 20 Given that polymer blends frequently suffer from compatibility issues, copolymers would be promising candidates for the development of high-performance and stable thermosets. 21 Current protein copolymers designed for excellent mechanical properties are mainly derived from well-defined pepti- des, 22−25 such as copolymers composed of silk-inspired peptide sequences and poly(ethylene oxide) 25 or copolymers composed of amyloidogenic peptide sequences and flexible linkers, 23 where the peptides form ordered β-sheet structures to provide stiffness and poly(ethylene oxide)/flexible linkers provide extensibility.…”

Micro- and Nanoplastics’ Effects on Protein Folding and Amyloidosis

“…Thanks to their biophysical properties and mechanical and chemical stabilities, amyloid fibrils have been used as building blocks in several applications, such as emulsions, membranes, and gels with high performances. When mixed with a plasticizer and a water-soluble polymer, the amyloids, through a fibrillization process, organized themselves in fibers and constituted a suitable building block for a new class of hybrid bioplastics [ 88 ]. Moreover, amyloid lysozyme fibrils were also conjugated with polyethyleneimine to create a new tool for the removal of lead (II) from water [ 89 ].…”

Water Processable Bioplastic Films from Functionalized Protein Fibrils

“…[ 13 ] An interesting recent development is hence the demonstration that by forming PNFs (derived from plant proteins or food proteins) in the presence of poly(vinyl alcohol) (PVA) and/or glycerol (GLY), biodegradable films with robust mechanical properties can be prepared. [ 14 ] In addition, PNFs functionalized with luminescent molecules could be mixed with PVA and GLY in order to form free standing LED‐coatings. [ 15 ] PNFs often display emergent optical properties such as intrinsic fluorescence and increased two‐photon absorption.…”