Classification of Biopolymers -
What you should know!
Biopolymers are grouped into various ways dependent on various scales. Biopolymers can be seprated into two general gatherings, to be specific biodegradable and non-biodegradable, and then again, into bio-based and non-bio-based biopolymers.
Based on their polymer spine, biopolymers can be arranged generally into the following groups: polyesters, polysaccharides, polycarbonates, polyamides, and vinyl polymers. These gatherings are again arranged into a few subgroups dependent on their cause.
Biopolymers can be characterized, contingent upon the idea of the repeating unit they are made of into three groups:
(1) Polysaccharides are made of sugars (for example cellulose found in plants)
(2) Proteins are made of amino acids (for example myoglobin found in muscle tissues)
(3) Nucleicacids are made of nucleotides (DNA, hereditary material of a given life form)
● In light of utilization, biopolymers can be named bioplastics, biosurfactant, biodetergent, bioadhesive, biofloculant, etc…
BIODEGRADABLE NATURAL POLYMERS
● To select a biomaterial for tissue engineering is the most critical step in scaffolds development. The main requirement should include biocompatible, non-toxic, providing favorable cellular interactions and tissue development, besides, the properties of mechanical strength, tensile strength etc. is also needed of synthetic polymer. Biodegradable should be requested and also should support the reconstruction of a new tissue without inflammation. According to the chemical structure of a vast variety of polymers as living organisms synthesized, they can be classified into major classes:
● Also basing on the advances in biotechnology, natural polymers can be obtained by the fermentation of microorganisms or in vitro production by enzymatic processes.
Based material classification
Biomaterials can be classified depending on based material; in this case they are classified into four main types of Biopolymers.
1) Sugar based Biopolymers
Biopolymers based on sugar can be produced by blowing, vacuum forming injection, and extrusion. Lactic acid polymers (Polyactides) are
created from milk sugar (lactose) which is extracted from maize, wheat and sugar beet. Polyactide are manufactured by methods like vacuum forming, blowing and injection molding, are resistant to water.
2) Starch based Biopolymers
Biopolymers based on starch acts as natural polymer and can be obtained from vegetables like wheat, tapioca, potatoes and maize.
The material is stored in tissues of plants as carbohydrates. It is composed of glucose and can be obtained from melting starch. This polymer is not present in animal tissues. Dextrans, produced by starch hydrolysis, which is a group of low-molecular-weight carbohydrates, enzymatically synthesized by immobilized Enterococcus faecalis Esawy dextransucrase onto biopolymer carriers.
3) Cellulose based Biopolymers
Biopolymers based on cellulose are used for packing cigarettes, CDs and confectionary. This polymer is composed of glucose and is the primary obtained from natural resources, plant cellular walls, like cotton, wood, wheat and corn.
4) Biopolymers based on Synthetic materials
Biopolymers based on Synthetic compounds also used for making biodegradable polymers such as aliphatic aromatic copolyesters are obtained from petroleum. They are compostable and bio-degradable completely though they are manufactured from synthetic components.
BIODEGRADABLE SYNTHETIC POLYMERS
Polyglycolide Acid (PGA)
It is a highly crystalline polymer. It also exhibits a high tensile modulus with a very low solubility in organic solvents. The currently most commonly used in synthetic biodegradable polymer are considered to be poly (glycolic acid) and poly (lactic acid). Polyglycolide is initially investigated for developing resorbable sutures because of its excellent fiber forming ability. Polyglycolides are broken down into glycine or converted into carbon dioxide and water via the citric acid cycle.
Polylactide Acid (PLA)
Similar to polyglycolide, it is also crystalline polymer. It has a glass transition temperature of 60–65ᵒC and a melting temperature of approximately 175ᵒC. Poly (L-lactide) is a slow-degrading polymer contrasted with polyglycolide. L-lactide (LPLA) homopolymer is a semicrystalline polymer with high tensile strength exhibitition, low elongation, and have a high modulus consequently that make them suitable in orthopedic fixation and sutures that have wild applications like load-bearing.
In adjusting the property of PGA in wide application, copolymer of PGA with the more hydrophobic poly (lactic corrosive) (PLA) were investigated dynamically. Compared to homopolymers, the intermediate co-polymers were found to be less stable. Various proportions of poly (lactide-co-glycolides) have been industrially evolved and are being explored for a wide scope of biomedical applications.
Two distinct criteria underline the meaning of a “biopolymer”:
(1) The source of the raw materials
(2) Polymer biodegradation.
Biopolymers produced from renewable raw materials (bio-based), and being biodegradable.
These polymers can be produced by either biological systems (microorganisms, animals, and plants) or synthesized chemically from biological starting materials (e.g., corn, sugar, starch, etc.)
Biodegradable bio-based biopolymers include:
(1) synthetic polymers from renewable resources such as poly (lactic acid);
(2) biopolymers produced by microorganisms, such as PHAs;
(3) natural occurring biopolymers.
Biopolymers produced from renewable raw materials (bio-based), and not being biodegradable.
These biopolymers can be produced from biomass or renewable resources and are non-biodegradable. Non-biodegradable bio-based biopolymers include
(1) renewable resource’s synthetic polymers such as specific polyamides from castor oil, specific polyesters based on bio propanediol, bio polyethylene (bio- LDPE, bio-HDPE), bio polypropylene (bio-PP), or bio poly (vinyl chloride) (bio-PVC) based on bioethanol (e.g., from sugarcane), etc.;
(2) natural occurring biopolymers such as natural rubber or amber.