natural biomaterials
Post on 15-Apr-2017
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Natural BiomaterialsPresented By:-
Anup Neupane (B1)Pragya Dhungel (B6)
andPranish Pradhan (B7)
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Biomaterial• A biomaterial is a nonviable material used in a medical device intended to interact with biological systems. (Williams 1987)
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Classes of Biomaterials• Metals• Polymers• Hydrogels• Bioresorbable and
Bioerodible material
• Ceramics, glasses and glass ceramics
•Natural Materials•Composites•Thin films, Grafts and coatings•Fabrics•Biologically functional materials
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Natural Biomaterials
• The natural biomaterials group includes naturally occurring biomaterials and chemical modifications of these materials.
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•Advantages• Biomimetic,• More
biocompatibility,• Capability of
designing biomaterials which function at molecular level,
• Controlled degradation
•Disadvantages• More
immunogenic• Structural
complexity• Mostly degraded
by natural enzymes
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Some Natural Biomaterials
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Polysaccharide• Carbohydrates with more than 10
monosaccharides units.• General uses : Wound healing Drug delivery
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Polysaccharide as biomaterial
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• Long chain linked sugar molecules.• Mainly found in plants.• Promotes bone regeneration.
Cellulose
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Amylose•A spiral polymer made up of D-glucose units.
•Sustained drug release
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Dextran• Expressed by bacteria (leuconostoc
mesenteroide),• Highly soluble and investigated as
blood plasma replacement (1940s),• Resists protein adsorption
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Chitin• Hydrophobic,• Derived mostly from exoskeleton of
Arthropods• N-deacetylated derivative- CHITOSAN• Wound healing, drug delivery, tissue
engineering scaffolds
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Glycosaminoglycans
• Occur naturally as a polysaccharide branches of protein chain to which they are covalently attached by oligosaccharide link.
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• Hyaluronan-promote angiogenesis and wound healing• Chondrotin Sulphate-adhesive for sealing corneal incision• Heparin-anticoagulant
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Polynucleotides• Repeating chain of nucleotide units • RNA and DNA• Detection of damage to cell caused
by biomaterials
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Protein• Long chain of amino acids linked by
peptide bonds,• Contains 20amino acids ,
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Structure of protein• Primary Structure
• Linear sequence of amino acids linked by peptide bonds
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Secondary Structure • Consists of α-helix and β-pleated
sheets
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Tertiary and Quaternary Structure
• The final arrangement of domains in the polypeptide
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Proteins as Biomaterials
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Silk• Natural protein fibre, mainly
composed of fibrinogen• Produced by larvae of
mulberry silkworm Bombyx mori• Mostly in beta conformation• Uses: Sutures, Scaffolds
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Keratin• Found in dermal parts, nails, hairs
etc.• 100% α-helix.• 18% Cys residue.• Nano fibrous mat for wound healing.
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Gelatin• Solubilized amorphous collagen,• Sustained drug delivery,• Bioadhesive .
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Fibrinogen• In blood.• Synthesized by hepatocytes in liver.• Guides better cellular behaviour.• Scaffolds.
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Elastin• Extensively interconnected, rubbery
network that can stretch and bend in any direction when stressed, giving connective tissue elasticity .
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Collagen
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Collagen • Main structural protein.• Most abundant,25%-35% of total
body protein.• Major part of ECM.• May be found as gel(Vitreous
humor),tight bundle of fibres(Tendon),angled fibres(Bone).
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Structure • Triple helix.• Mostly contains Glycine and Proline.• Both have their own importance.
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Structure Contd…• Glycine present in
every 3rd position.
• -Gly-X-Y sequence where:- X=Pro(mostly)
Y=Hyp or Hyl(mostly)
• Triple helix stabilized by H-bonds.
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Collagen Disorders• By mutation which
causes the deformation of structure.
• Ehlers-Danlos Syndrome:-
— Stretchy skin.• Osteogenesis
Imperfecta:—Bones that easily bend
and fracture.—Known as Brittle Bone
Syndrome.
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Types
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Properties of CollagenMechanical Properties:-
• Stiffness=1000MPa
• Ultimate Tensile Strength=100MPa
• Young’s Modulus=2.9GPa
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Electrical properties:-• Electrically neutral.
• Piezoelectric in nature.
• Electrostatic state changes with changing pH.
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Biological Properties:-• Collagen-Platelets interaction.
• Collagen-Immune system interaction.
• Collagen in cell differentiation. Forms morphogenetic templates. Mediates intercellular flow of
information.
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Isolation and PurificationCollection of collagenous tissues.• Eg:-Rat tail, Bovine Achilles tendon,
etc.
Dissolution of tissues.1. With salt:-• Gives salt soluble fraction of
collagen.• Treated with 0.5M Na2HPO4 .• Ultracentrifuged and obtained in
supernatant.
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Isolation and Purification 2. With acid:- Tendons + 0.5M Acetic acid 0.05M EDTA 48-96hrs pH=2.5-3.0
Acid soluble fraction
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Isolation and Purification3. Enzymatic isolation:-
• Same as acidic isolation.
• BUT, also pepsin 0.05g per 100g tissue.
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Isolation and PurificationPurification:-• By dialyzation vs. different
concentration of Na2HPO4 .• 0.01M for salt soluble; 0.05M for acid
soluble;0.02M for collagen isolated enzymatically.
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Extraction of Collagen from Rat Tail:-Dissolution in acetic acid
Mixing and Lyophilization
Mixing with acetic acid
1.Centrifugation
2.Degassing
3.Sterilization
1%NaOH
pH=6.5-7
pH=3.5
Collagen Gel
Characterization• Protein Amount Determination:-
Indirectly from the amount of hydroxyproline.
• Viscosity Measurement:- By Cannon-Fenske viscometer.
• SDS-PAGE:- Technique for separating biological macromolecules according to their electrophoretic motility.
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References• http://www.jungsanbiomed.com/• http://www.columbia.edu/• http://www.nature.com/• http://www.mdpi.com/• http://www.jbc.org/• http://www.woodwisdom.net/• www.books.google.com• Ratner Buddy D., Et .al Biomaterial Science:An
Introduction to Materials in Medicine.• Lippincott’s Biochemistry.• Lehninger’s Biochemistry
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