What are Biopolymers?
Biopolymers are polymers produced from natural sources. These can either be chemically synthesised from biological materials or biosynthesised by living organisms. These are made up of monomeric units bonded together by covalent bonds. These monomeric units form larger molecules. As biopolymers are derived from living organisms like plants and microbes, they are a renewable resource, unlike most polymers which are petroleum-based polymers.
Generally, biopolymers are degradable. They find use in various industries ranging from food industries to manufacturing, packaging and biomedical engineering. Biopolymers are promising materials owing to their characteristics like abundance, biocompatibility and unique properties like non-toxicity etc. With some nanosized reinforcements to enhance its properties and practical applications, biopolymers are being researched for its use in more and more ways possible.
Examples of biopolymers are protein, starch, cellulose, DNA, RNA, lipids, collagen, carbohydrates etc.
Types of Biopolymers
Biopolymers can be classified according to various scales. These classifications are based on their origin, a number of monomeric units, on the basis of degradability, their heat response etc. Some of the classifications are:
On the Basis of Type
Sugar-based polymers- Starch or sucrose is used as input for manufacturing. Lactic acid polymers are created using lactose from potatoes, maise, etc.
Starch-based polymers- Starch acts as a natural polymer, composed of glucose. It is found in plant tissues.
Cellulose-based biopolymers- Used for packaging, this polymer is made up of glucose obtained from natural sources like cotton. Eg. cellophane.
Synthetic materials- Degradable polymers can be made from synthetic materials obtained from petroleum.
On the Basis of Origin
Natural biopolymers- These are natural biopolymers biosynthesised by living organisms.
Synthetic biopolymers - These are polymers made up of renewable materials like polylactic acid which are degradable.
Microbial- Biopolymers produced by microorganisms.
On the Basis of Monomeric Units
Polysaccharides-These are carbohydrate chains which are branched or are linear: Eg. starch, cellulose, etc.
Proteins- Polymers made up of amino acids. Eg. collagen, fibrin etc.
Polynucleotides - Nucleic acids are long polymer chains composed of 13 or more monomeric units. Eg. DNA, RNA etc.
Difference Between Biopolymers and Synthetic Polymers
Applications of Biopolymers
Biopolymers have unique properties and are an abundant material. Due to their unique properties and structures, biopolymers find their application in many places.
Biomedical
Biopolymers are very widely used in the biomedical field. Due to the properties like degradable and non-toxic, biocompatible properties, etc., they are used in tissue engineering, pharmaceutical industry, medicines, drug delivery etc. Polypeptides are inexpensive and easily available, therefore find various uses in biomedical materials.
Drug delivery systems- Biopolymers like collagen and chitosan are used as drug delivery systems to target the drug and improve drug absorption. Collagen sponges are widely used to treat burn wounds. Both collagen and chitosan are used in tissue engineering. These are very porous and allow the wounds to heal.
Industrial Use
Biopolymers owing to their unique properties find use as industry-standard materials. They are combined with some materials to reinforce the properties of these biopolymers to enhance their desired properties and practical applications. These are widely used in packaging; PHA, polylactic acid and starch being inexpensive and readily available are perfect for this task. They also have barrier characteristics which are not available in other polymers, like these are water-resistant.
Biopolymers are used in the automotive industry to make interior and exterior parts, electrical components, engine, exhaust, steering wheels etc. Biopolymers are added to cement during concrete preparation to increase the desired properties. They are used in the construction industry of interior decoration. Chitosan has properties that remove metals from the water which makes it usable for water purification. Due to its antimicrobial properties, it is also used at places to stop microorganism growth.
Other Applications
Agricultural/Fishery- Fishing lines, fertilisers, beehives, nets, traps, etc.
Electronics- In the manufacturing of audio devices, printed circuit boards, insulated wires, cables and other electronic devices.
Cosmetics - Used for cleaning purposes, pedicure and manicure, also in cosmetic products like sunscreen, hair products, creams etc.
Sports/Toys- Used to make sports equipment like footballs and other hollow balls, cleats, badminton, golf equipment, etc.
Nanotechnology- Also used in the production of nanomaterials. Biopolymers have certain unique properties which make them useful in branches of science, for example - the green chemistry.
Common Biopolymers and their uses
Collagen- It is a type of protein which is most abundant in humans (30%). It is made up of amino acids which are further made up of carbon, hydrogen and oxygen. Collagen contains special types of amino acids called Glycine, Proline, Hydroxyproline and Arginine. Collagen gives strength to our various body parts and also protects them. It is a major part of human’s skin and nails. As it is composed of three chains, it has a triple helix like structure.
Gelatin- It is widely used in various industries due to its properties of biodegradability and biocompatibility. Gelatin is a water soluble protein which is derived from collagen (natural polymer). Its main function is to look after the connective tissues such as bones, tenders, cartilage etc. There are 16 different collagen types in the human body. The most prominent ones are the Type I, II and III or collagen I, II and III).
Starch- Starch is one such biopolymer which is found in abundance. It is used widely as it is inexpensive, renewable and biodegradable. Starch is a naturally occurring biodegradable polymer which is easily available from agriculture based activities. People use starch in the food products as well as non food products.
Silk fibroin- It is another type of protein polymer which is obtained from silkworms. It is generally used in fashion textiles and medical stitching.
FAQs on Biopolymers
1. What are biopolymers? Provide some common examples.
Biopolymers are polymers produced by living organisms or synthesised from biological starting materials. They consist of repeating monomer units joined by covalent bonds. Unlike most synthetic polymers derived from petroleum, biopolymers are a renewable resource. Common examples include starch, cellulose, proteins (like collagen and keratin), nucleic acids (DNA and RNA), and polylactic acid (PLA).
2. What are the main advantages of using biopolymers over traditional synthetic polymers?
The main advantages of biopolymers stem from their natural origin and properties. These include:
- Renewability: They are sourced from biological materials like plants and microbes, which are sustainable.
- Biodegradability: Many biopolymers can be broken down by microorganisms, reducing plastic waste and environmental pollution.
- Biocompatibility: They are often non-toxic and compatible with living tissues, making them ideal for medical applications like drug delivery and tissue engineering.
- Reduced Carbon Footprint: Their production often results in lower greenhouse gas emissions compared to petroleum-based plastics.
3. How are biopolymers classified based on their monomer units?
Biopolymers can be classified based on the type of repeating monomeric units they contain. The main types are:
- Polysaccharides: These are long chains of monosaccharide (sugar) units. Key examples are starch and cellulose.
- Proteins or Polypeptides: These are polymers made of amino acids linked by peptide bonds. Examples include collagen, silk, and gelatin.
- Polynucleotides: These are polymers of nucleotides, which form the basis of genetic material. The most well-known examples are DNA and RNA.
- Polyesters: Some bacteria produce natural polyesters, such as PHBV (Poly-β-hydroxybutyrate-co-β-hydroxy valerate).
4. What is the difference between a biopolymer and a biodegradable polymer?
While the terms are related, they are not interchangeable. A biopolymer is defined by its origin—it must be derived from a biological source. A biodegradable polymer is defined by its end-of-life property—it can be broken down by natural processes. Therefore, not all biopolymers are biodegradable, and some synthetic, fossil-fuel-derived polymers can be biodegradable.
5. How do proteins like collagen and silk function as important biopolymers?
Proteins are crucial biopolymers with highly specific functions determined by their structure.
- Collagen is a structural protein that forms a triple helix, providing strength and flexibility to connective tissues, skin, and bones. Its biocompatibility makes it vital for medical applications like wound dressings.
- Silk fibroin is another structural protein known for its exceptional tensile strength and lustre. It is primarily used in textiles and for creating strong, biocompatible medical sutures.
6. Why is PHBV considered an important biopolymer for the environment?
PHBV (Poly-β-hydroxybutyrate-co-β-hydroxy valerate) is an important biopolymer because it is both bio-based and biodegradable. It is a biopolyester produced by bacteria, making it a renewable resource. Critically, it undergoes bacterial degradation in the environment, breaking down into carbon dioxide and water. This makes it an excellent eco-friendly alternative to non-biodegradable plastics like polypropylene, especially for use in packaging and disposable items.
7. What are some key applications of biopolymers in the medical field?
Due to their biocompatibility and biodegradability, biopolymers are extensively used in medicine. Key applications include:
- Drug Delivery Systems: Biopolymers like chitosan and collagen are used to create capsules that release drugs in a controlled manner within the body.
- Tissue Engineering: Porous scaffolds made from biopolymers like polylactic acid (PLA) are used to support cell growth and help regenerate damaged tissues.
- Medical Implants and Sutures: Biodegradable screws, plates, and sutures made from biopolymers can dissolve in the body over time, eliminating the need for a second surgery for removal.
