Natural Polymers as Biomaterials (Nov 12)- Summary Sheet.pdf

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Queen's University
Mechanical and Materials Engineering Courses
MECH 478

Natural Polymers as Biomaterials By James Clarke and Ian Morewood Overview  Natural polymers are polymers produced by living organisms and are an essential part of life. They are found in your body as structural components of hair, skin, muscle, bone and blood vessels, as well as your RNA and DNA.  There are three main groups of natural polymers: o Proteins and Polypeptides (Silk, Karatin, Collagen, Gelatin, Fibrinogen, Elastin, Actin, Myosin)  Main building blocks are sugar molecules o Polysaccharides (Cellulose (cotton), Amylose, Dextran, Chitin, Glycoaminoglycans)  Main building blocks are amino acids o Polynucleotides (Deoxyribonucleic acids (DNA), Ribonucleic acids (RNA)) History Natural polymers have traditionally been used in order to treat and facilitate wound healing. Silk and linen have been used as suture material since as far back as ancient Egypt, while cotton, wool, and linen have been commonly used for medical fibers such as bandages and other wound dressings. These materials were utilized due to their reasonable biocompatibility, high strength, and permeability to air which accelerated wound healing and protected against foreign contamination. Polymers such as wood and leather have also been used in the construction of prosthesis due to their mechanical properties and resistance to wear. Natural verses Synthetic Polymers Advantages  Often similar or identical to macromolecular substances the body is prepared to recognize and deal with metabolically.  The ability to create biomaterials that are stable on the macroscopic and molecular level.  Low inflammatory response.  Able to degrade by naturally occurring enzymes and metabolized. This allows for the design of implants that only need to function for a certain amount of time. Disadvantages  They can be immunogenic, most problematic for proteins.  They are structurally more complex which can make physical and chemical manipulation harder o Thermoplastic methods of molding are difficult with proteins because they tend to decompose below their melting temperature  High variability in the macromolecular structure of substances derived from animal products. o Species and tissue specificity Proteins and Polypeptides Polysaccharides Polynucleotides Long carbohydrate molecules An arrangement of 13 or more Consists of varying arrangements of molecules consisting of repeated monomer Structure of amino acids units joined together by glycosidic nucleotide monomers covalently bonded in a chain bonds Example Silk Collagen Cellulose Chitin(Chitosan) DNA RNA Two long polymers with Typically a single Varies by source, can Consists primarily of A copolymer of N- backbones strand of polymer
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