Polymer Basics for Biopolymers


Biopolymers have revolutionized lifesaving treatments and medical devices used in healthcare today. Scientists use these macromolecules to deliver drugs to patients, create hydrogels for contact lenses, and regenerate cartilage for orthopedic procedures. In this article, you'll learn how biopolymers have changed the medical world. 

Characteristics and Properties of Biopolymers

According to the IUPAC, biopolymers are macromolecules created from natural sources. They are biosynthesized from biological material or biosynthesized by a living organism's cells. Each one consists of monomeric units covalently bonded to form larger molecules.
These polymers form primary structures according to their chemical composition and monomer sequence arrangements. Additionally, biopolymers fold into characteristic shapes that determine their biological functions. Structural biology is the scientific branch that studies biopolymer shapes, functions, and roles in nature.
Biologists classify biopolymers based on their primary structure and monomer sequences. They generally fall into three categories: polynucleotides, polypeptides, and polysaccharides.

  • Polynucleotides - These are linear polymers composed of 13 or more nucleotide monomers. Examples include Ribonucleic Acid (RNA) and Deoxyribonucleic Acid (DNA). 
  • Polypeptides and proteins - These are longer, continuous, unbranched peptide chains of approximately 50 amino acids. Polypeptides, which contain more than 50 amino acids, are known as proteins. Examples include actin, collagen, and fibrin. 
  • Polysaccharides - These are linear or branched polymeric carbohydrates, which can react with water (hydrolysis) using amylase enzymes as a catalyst. This produces constituent sugars (monosaccharides or oligosaccharides), whose structures include linear and highly branched polysaccharides. Examples are starches, galactogen, glycogen, and cellulose. These are the most abundant carbohydrate found in nature, and some serve as short-term sources of energy in plants and animals.

Biopolymers are not only naturally created, some companies mass produce them for commercial use. These producers only incorporate a few biopolymers for plastics. 


Production Methods

Natural biopolymers, including starches, vegetable oils, and soy proteins, can be extracted from bacterial sources and crops. Additionally, microorganisms and plants can produce lactic acids that biologists can polymerize into bioplastics.
Fermentation is another process used to produce biopolymers. Bacteria and other microorganisms produce biopolymers in fermentation tanks called bioreactors. Manufacturers later extract these macromolecules to create plastics.
Genetic engineering is a recent method used to produce biopolymers. Biotechnologists introduce bacteria genes in plants that make bacterial plastics. They later harvest the plastics from the green material.

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Common Uses in Medical Devices and Life Sciences

Medical manufacturers have used biopolymers to develop many medical devices. These are preferred materials due to their biocompatibility, biofunctionality, and biodegradability, making them sound drug delivery systems.
Additionally, several medical devices incorporate polyhydroxyalkanoates (PHAs), or thermoplastic biopolymers. They include controlled drug release, surgical sutures, gauzes, bone plates, gauzes, and wound care.
Some businesses integrate biopolymers to make tools that release insulin, contraceptives, and hormones. Other devices deliver proteins, anticancer, and antimalarial agents. They also incorporate these macromolecules in microcapsules, implants, and hollow fibers.
Additionally, physicians prefer polylactide sutures made from biopolymers because they disappear into wounds. Orthopedic surgeons use materials containing biopolymers as scaffolding to generate new cartilage within the body.
Healthcare manufacturers use collagen and gelatin hydrogels to make drug-delivery systems and contact lenses. They also utilize silk fibers to develop autologous tissue-engineered anterior cruciate ligaments (ACL) using a patient's own stem cells.
Biopolymers are also used in skin regeneration and grafting to treat wounds or burns.


Best Methods of Sterilization

There are several sterilization methods for biopolymers: the autoclave, dry heat, Ethylene Oxide (EtO), gamma irradiation, and electron beam.

  • Poly(L-lactide) (PLLA): Autoclave offers fair sterilization for PLLA. Preferred methods are dry heat, EtO, gamma irradiation, and electron beam.   
  • Polylactic Acid (PLA): Autoclave provides inadequate sterilization for PLAs, while dry heat offers a fair amount. EtO, gamma irradiation, and electron beam are more reliable techniques.
  • Polyhydroxybutyrate (PHB): Autoclave and dry heat provide inadequate sterilization for this polymer. Gamma irradiation and electron beam are fair methods, while EtO provides the best cleansing. 
  • Polyglycolic acid (PGA): Every process can provide excellent sterilization to PGAs, including autoclave, dry heat, EtO, gamma irradiation, and electron beam. 
  • Poly(lactic-co-glycolic acid) (PLGA): Autoclaves and dry heat are poor sterilization methods for PLGAs. Gamma irradiation and electron beam are fair methods, while EtO is the superior process.
  • Polycaprolactone (PCL): Autoclaves provide poor sterilization for PCLs. The best methods are dry heat, EtO, gamma irradiation, and electron beam.



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