Plastic is one of the most versatile and convenient materials used in every corner of the world by almost everyone, at the same time, it is responsible for affecting the health and lives of all living organisms in some way or the other. Above 8 million tonnes of plastic ends up in the ocean, which causes severe damage to the environment and marine wildlife which can be harmfully affected by this plastic by either getting entangled in them or eating them.
Research led by Jingjing Li and Yawei Liu (Chinese Academy of Sciences, Changchun, China), as well as Bo Wei (First Medical Center of PLA General Hospital), has introduced a new way of synthesizing protein-based plastics that are biodegradable and with properties that can serve different needs.
The existing methods of producing bioplastics from natural materials like starch and synthetic biomaterials like polylactive acid have shown inefficiencies and an inability to biodegrade in most cases. They are also often an energy-intensive and complex process. This study aims to tackle those problems and produce plastics that are easily processed, biodegradable, durable, biocompatible, and have favourable mechanical properties.
To accomplish this, they created two lysine-rich proteins and grew them in bacterial cultures: "ELP" is a polypeptide that is structurally similar to the connective tissue protein elastin. It lacks defined folding, which results in toughness and elasticity. SRT is made up of ELP as well as crystalline segments of a squid protein with a β-sheet structure.
The lysine amino side-groups of ELP (or SRT) crosslink with a polyethylene glycol (PEG) derivative. If the crosslinking takes place in water, the material can simply be dried in a mould. As a result, a tough, transparent, solvent-resistant bioplastic is created. The proportion of PEG can be changed to change the mechanical properties. This enables bioplastics of any shape and high mechanical strength at room temperature to be manufactured without toxic chemicals or complex processing steps such as liquefaction, extrusion or blow molding. Their breaking strength exceeds the breaking strength of many commercially available plastics. The only problem yet to be solved is that they swell in water. Different properties/ products with various uses can be achieved by cross-linking ELP with different solutions, peptides, etc. Bioplastics can also be used to make toys, for sealing wounds, and make implants that break down entirely within a few weeks
These Protein-based Bioplastics can be easily degraded by the natural enzyme elastase. This can help eliminate one of the biggest drawbacks of plastics which is their ridiculously long lifetime on earth in which they cause major harm.
Here’s to hoping that such research helps in tackling the PROBLEM that is PLASTIC and save those adorable turtles at the same time!
Reference:
Juanjuan Su et al, Biosynthetic Structural Proteins with Super Plasticity, Extraordinary Mechanical Performance, Biodegradability, Biocompatibility and Information Storage Ability, Angewandte Chemie International Edition (2022).
By Bishakha Choudhary
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