Biodegradable polymers are most often referred to as “biopolymers” because most of these polymers are derived from various natural sources. There are few in the list of biodegradable biopolymers in nature. PLA, PHA and starch are the most commonly used biopolymers that have minimal or minimal impact on the increasing environmental carbon footprint. However, biodegradability is a characteristic of polymers that is independent of their origin and can be altered after tuning at the molecular level. Therefore, some polymers are produced from petroleum feedstocks but are biodegradable. Therefore, in addition to naturally derived biopolymers, there are also petroleum-based biodegradable biopolymers.
Natural Biopolymer
Natural biopolymers are natural polymers produced by living organisms; in other words, they are polymeric biomolecules derived from cells or extracellular material. Biopolymers contain monomeric units that are covalently bonded to form larger structures. Based on the monomer units used and the structure of the biopolymers formed, biopolymers are divided into three broad categories: polynucleotides, polypeptides, and polysaccharides. More specifically, polynucleotides such as RNA and DNA are long polymeric monomers composed of 13 or more nucleotides. Polypeptides or proteins are short polymers of amino acids, prime examples include collagen, actin and fibrin. The last class, polysaccharides, are usually linearly bonded polymeric carbohydrate structures, some examples including cellulose and alginates. Other examples of biopolymers include rubber, suberin, melanin, and lignin.
Synthetic Biopolymers
Synthetic biopolymers are polymers modified from natural polymers or chemically synthesized from synthetic monomers, which can undergo natural degradation without leaving any residues that are harmful to life and the natural environment. In the past few years, synthetic biopolymers have attracted much attention due to their superiority to natural polymers in terms of stability and flexibility for various applications. On the other hand, synthetic biopolymers are favored over synthetic polymers because they are biodegradable and environmentally friendly. Thanks to new molecular design tools and advances in polymer chemistry, it is now possible to tailor the synthesis of synthetic biopolymers to suit their specific application. Synthetic biopolymers have become one of the most important applications in medicine due to their unique properties, such as stability, controlled release, non-immunogenicity, and clearance from the body, suitable for their use in humans. Synthetic biopolymers are mainly aliphatic or aromatic polyesters or copolyesters synthesized from monomers derived from petroleum feedstocks through chemical reactions.
Medical Applications of Biopolymers
Since one of the main purposes of biomedical engineering is to mimic body parts to maintain normal bodily functions, biopolymers are widely used in tissue engineering, medical device and pharmaceutical industries due to their biocompatibility. Many biopolymers are useful in regenerative medicine, tissue engineering, drug delivery, and overall medical applications due to their mechanical properties. They have properties such as wound healing, bioactive catalysis and non-toxicity. Compared with biopolymers, synthetic polymers may exhibit various disadvantages, such as immunogenic rejection and toxicity after degradation, similar to the human body, and many biopolymers generally have better body integration as they also have more complex structure.
More specifically, polypeptides such as collagen and silk are biocompatible materials that are used in pioneering research because they are inexpensive and readily available materials. The gelatin polymer is commonly used in wound dressings where it acts as an adhesive. In addition, biopolymer stent is allowed to hold drugs and other nutrients that can be used to provide healing to the wound.
Medical Application Cases of Biopolymers
Collagen
Collagen-based Drug Delivery SystemsrnCollagen membranes act like barrier membranes and can be used to treat tissue infections such as infected corneal tissue or liver cancer. Collagen membranes have all been used in gene delivery vehicles to promote bone formation.
Collagen SpongesrnCollagen sponges are used as dressings to treat burn victims and other severe wounds. Collagen-based implants are used for cultured skin cells or drug carriers for burn wounds and skin replacement.
Collagen as a Hemostatic AgentrnWhen collagen interacts with platelets, it causes the blood to clot rapidly. This rapid coagulation creates a temporary framework so the fibrous matrix can be regenerated by host cells. Collagen hemostatic agents reduce blood loss from tissues and help manage bleeding from cellular organs such as the liver and spleen.
Chitosan
Chitosan is another popular biopolymer in biomedical research. Chitosan is the main component of crustaceans and insect exoskeletons and the second largest biopolymer in the world. Chitosan has many excellent properties in the biomedical field. Chitosan is biocompatible and highly bioactive, which means it stimulates a beneficial response in the body, biodegrades, eliminating a second surgery in implant applications, and can form gels and films, and has selective permeability. These properties allow various biomedical applications of chitosan.
Chitosan as Drug DeliveryrnChitosan is mainly used for targeted drugs because of its potential to improve drug absorption and stability. In addition, chitosan combined with anticancer agents can also produce better anticancer effects by gradually releasing free drugs into cancer tissues.
Chitosan as an antimicrobial agentrnChitosan is used to prevent the growth of microorganisms. It exerts antibacterial function in microorganisms such as algae, fungi, bacteria and gram-positive bacteria in different yeast species.
Chitosan Composites for Tissue EngineeringrnThe mixed efficacy of chitosan and alginate can be used together to form functional wound dressings. These dressings create a moist environment that aids in the healing process. This wound dressing is also highly biocompatible, biodegradable, and has a porous structure that allows cells to grow into the dressing.