Options to Improve the Mechanical Properties of Protein-Based Materials

Abstract

While bio-based but chemically synthesized polymers such as polylactic acid require industrial conditions for biodegradation, protein-based materials are home compostable and show high potential for disposable products that are not collected. However, so far, such materials lack in their mechanical properties to reach the requirements for, e.g., packaging applications. Relevant measures for such a modification of protein-based materials are plasticization and cross-linking; the former increasing the elasticity and the latter the tensile strength of the polymer matrix. The assessment shows that compared to other polymers, the major bottleneck of proteins is their complex structure, which can, if developed accordingly, be used to design materials with desired functional properties. Chemicals can act as cross-linkers but require controlled reaction conditions. Physical methods such as heat curing and radiation show higher effectiveness but are not easy to control and can even damage the polymer backbone. Concerning plasticization, effectiveness and compatibility follow opposite trends due to weak interactions between the plasticizer and the protein. Internal plasticization by covalent bonding surpasses these limitations but requires further research specific for each protein. In addition, synergistic approaches, where different plasticization/cross-linking methods are combined, have shown high potential and emphasize the complexity in the design of the polymer matrix.

Inhibitory Effects of LRP1-Based Immunotherapy on Cardiac Extracellular Matrix Biophysical Alterations Induced by Hypercholesterolemia

“…In line with calorimetric results, these results indicate that cardiac plasticization is caused by an extracellular phenomenon independent of intracellular cholesterol levels, in contrast to the other biophysical alterations in the ECM components. Due to their amphiphilic character, biomacromolecules are also known to interact with lipids via hydrophobic association, and lipids can act as efficient plasticizers. , Previous studies from our group have shown that aggregated LDL favors a softness of tropoelastin . In addition, CE-enriched lipoproteins per se have been reported to produce an increase in the free volume of ECM macromolecules, causing a swelling and plasticization of the tissues. , In line, the reduction of circulating levels of CE-enriched lipoprotein levels improved arterial stiffness in humans .…”

“…Due to their amphiphilic character, biomacromolecules are also known to interact with lipids via hydrophobic association, and lipids can act as efficient plasticizers. 63,65 Previous studies from our group have shown that aggregated LDL favors a softness of tropoelastin. 25 In addition, CE-enriched lipoproteins per se have been reported to produce an increase in the free volume of ECM macromolecules, causing a swelling and plasticization of the tissues.…”

Analysis of Hydroxyapatite/Gelatine Composition on the Filament Formation Using Piston Extrusion Method

“…In this study, no cross-linking agent was used in the HA/gelatine bio composite mixture. Crosslinking agents play a role in connecting molecular chains in bio composite materials so that later they can form strong cross-links and increase the strength and stiffness of the material ( [42], [43]). Adding a cross-linking agent to the HA/gelatine bio composite solution also reduces the tendency for melting or deformation when passing through the nozzle [44].…”

Mechanical Properties of Protein-Based Food Packaging Materials

“…All proteins have complex polymeric structures; however, they are not structurally stable by nature. Using different strategies, the mechanical characteristics of protein-based films can be enhanced, such as by introducing a plasticizer into the protein matrix [ 59 ]. Different animal-based proteins including gelatin, casein, and whey protein are utilized in forming edible films due to their significant film-forming characteristics, such as mechanical and barrier characteristics.…”