Biopolymers
Biopolymers are polymers that formed in natural conditions by complex metabolic processes during cell’s growth cycles of most organisms. To synthesize biopolymers living organisms use simple monomeric units such as sugars, sugar derivatives, amino acids, nucleotides, etc. Starch, cellulose, alginate, lignin, gelatin, proteins, peptides, & nucleic acids are all examples of biopolymers. These biopolymers contribute a significant fraction of cellular dry weight in most organisms. There is an increasing interest in more complex polysaccharides such as chitin, chitosan, curdlan, hyaluronic acid, pullulan, and xantham produced by bacteria and fungi.
Biopolymers are biodegradable, but they differ from biodegradable polymers, as biodegradable polymers are artificially synthesized from natural sources. Biobased polymers are derived from renewable sources, whereas bioplastics are not always produced from natural sources, and both are usually biodegradable. Biopolymers can be sustainable, carbon-neutral, and renewable. Some biodegradable biopolymers are also compostable. For example, Poly Lactic Acid (PLA) can be broken down by 90% in an industrial composting plant.
Biopolymers have been known from the beginning of civilizations to have many applications; for example, natural rubber, cotton, wool, cork, and leather are all biopolymers. In the twenty-first century, biopolymer research and development have gained tremendous interest, therefore, not limited to these areas and the use of biopolymers broadening to the field of agriculture film, soil-retention sheeting, waste bags, packaging material, food containers, drug-delivery systems, filtration systems, bioresorbable scaffolds for tissue engineering, surgical implant devices, wound healing products, hygiene, and protective clothing, etc. Biopolymers may lack the mechanical properties and stability for medical applications in aqueous environments. Cross-linking of biopolymers using nontoxic reagents can improve their functionality without causing cytotoxicity. [Sohidul Islam]
