Post on 23-Aug-2014
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Biomedical Polymers PRESENTED BY MR. D.A.PAWADE
GUIDED BY DR:N.H.ALOORKAR
SATARA COLLEGE OF PHARMACY,SATARA
CONTENTS
• Introduction
• Classification
• Selection parameters for biomedical
polymers
• Applications
• Conclusion2
What is the Biomedical Polymers ?
INTRODUCTION
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BIOMEDICAL POLYMERS
Macromolecular compound obtained from natural origin.
Chemical nature - polysaccharides, protein and bacterial polyesters.
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Flexibility; Resistance to biochemical attack; Good biocompatibility; Light weight; Available in a wide variety of compositions with
adequate physical and mechanical properties and
Can be easily manufactured into products with the desired shape.
Properties Of Biomedical Polymers
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Classification
Biomedical Polymers
Natural Polymers
Synthetic Polymers
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Natural polymers, or polymers, derived from living
creatures, are of great interest in the biomaterials
field. Properties of natural polymers:
Biodegradable;
Non-toxic/ non-inflammatory;
Mechanically similar to the tissue to be replaced;
Highly porous;
Natural polymers
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Encouraging of cell attachments and growth;
Easy and cheap to manufacture
Capable of attachment with other molecules (
to potentially increase scaffold interaction
with normal tissue).
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Example of natural polymers
A. Collagen
B. Cellulose
C. Alginates
D. Dextrans and
E. Chitosan
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Collagen• Consist of three intertwined protein
chains, helical structure• Collagen…..non-toxic, minimal
immune response• Can be processed into a variety formats– Porous sponges, Gels, and Sheets
• Applications– Surgery, Drug delivery, Prosthetic
implants and tissue-engineering of multiple organs
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Derived from chitin, present in hard exoskeletons of shellfish like shrimp and crab
Chitosan desirable properties Minimal foreign body reactionControllable mechanical biodegradation
propertiesApplications
In the engineering of cartilage, nerve, and liver tissue,
wound dressing and drug delivery devices
Chitosan
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Alginate• A polysaccharide derived from brown
seaweed Can be processed easily in water Non-toxic Biodegradable Controllable porosity• Forms a solid gel under mild processing
conditions• Applications in Liver, nerve, heart, cartilage & tissue-
engineering 12
Synthetic Polymers
Advantages of Synthetic PolymersEase of manufacturabilityprocess abilityreasonable cost
The Required Properties Biocompatibility Sterilizability Physical Property Manufacturability
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Applications:
Medical disposable supplies, Prosthetic materials, Dental materials, implants, dressings, polymeric drug delivery, tissue engineering products
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Synthetic Polymers
Example of Synthetic Polymers :
(PTFE) Polytetrafluoroethylene
Polyethylene, (PE)
Polypropylene, (PP)
Poly (methyl methacrylate), PMMA
Materials in Maxillofacial Prosthetic
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Synthetic Polymers
Biostable
Bioerodible
Water soluble
Other polymer
s
Classification of synthetic polymers
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• Polymers that are sufficiently biostable to allow their long term use in artificial organs blood pumps, blood vessel prostheses, heart valves, skeletal joints, kidney prostheses.
• A polymer must fulfill certain critical requirements if it is to be used in an artificial organ.
It must be physiologically inert
The polymer itself should be stable during many years of exposure to hydrolytic or oxidative conditions at body temperature
Biostable Polymers
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It must be strong and resistant to impact (when it is used as structural material to replace the bone).
The polymer must be sufficiently stable chemically or thermally that it can be sterilized by chemicals or by heat.
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Polymers that are bioerodible materials that will serve a short term purpose in the body and then decompose to small molecules that can be metabolized or excreted, sometimes with the concurrent release of drug molecules.
Mostly bioerodible polymers used as surgical sutures, tissue in growth materials, or controlled release of drug.
Bioerodible Polymers
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Water-soluble polymers (usually bioerodible) that form part of plasma or whole blood substitute solutions or which function as macromolecular drugs.
Applications:
Improvement in the behavior of pharmaceuticals.
Used in synthetic blood substitutes as viscosity enhancers or as oxygen-transport macromolecules.
Water Soluble Polymers
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The design and selection of biomaterials depend on different properties –
Host Response
Biocompatibility
Biofunctionality
Functional Tissue Structure and Pathobiology
Toxicology
Appropriate Design and Manufacturability
Mechanical Properties of Biomedical polymers
Selection Parameters For Biomedical Polymers
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Host Response: The response of the host organism (local
and systemic) to the implanted polymeric material or device.
Biocompatibility : The ability of a material to perform
with an appropriate host response, in a specific application.
Toxicology: Should not be toxic.
Appropriate Design and Manufacturability:
Biomaterials should be machinable, moldable, extrudable.
Mechanical Properties of Biomedical polymers:
Tensile strength, yield strength, elastic modulus, surface
finish, creep, and hardness. 22
Cardiovascular Applications
Bones, Joints, And Teeth
Contact Lenses And Intraocular Lenses
Artificial Kidney And Hemodialysis Materials
Oxygen-Transport Membranes
Surgical Sutures
Tissue Ingrowth Polymers
Controlled Release Of Drugs
Application
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Heart Valves and Vascular Prostheses
The Artificial Heart
Heart pump designs
Cardiovascular Application
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HEART VALVES
Damaged heart valves, weakened arterial
walls, and blocked arteries constitute some of
the commonest cardiovascular disorders.
Silicone rubber is used because of its
inertness, elasticity, and low capacity to cause
blood clotting.
Poly(tetrafluoroethylene) 25
Artificial Heart
Artificial hearts are a mechanical device, they
are typically used in order to bridge the time
to heart transplantation, or to permanently
replace the heart in case transplantation is
impossible.
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Artificial Heart
The heart is conceptually simple, it’s formed by
synthetic materials and power supplies. A
possible consequence it could be the body
rejection. These complications limited the
lifespan of early human recipients to hours or
days
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ABIO HEART
It’s the last artificial heart invented. It’s
made by titanium and a special plastic in
which the blood doesn’t stick. The heart has
got flexible walls with silicon, a motor that
moves it, and in the valve it controls the
pressure.
5 years are the life of this hearts.
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Heart Pump Designs
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Bones, Joints, And Teeth
Occasionally repaired with the use of polyurethanes,
epoxy resins, and rapid curing vinyl resins.
Silicone rubber rods and closed cell sponges- replacement
finger and wrist joints.
Elbow joints- vinyl polymers and nylon
Knee joints- cellophane and, more recently, silicone
rubber
Poly(methyl methacrylate) is the principal polymer used
both for acrylic teeth and for the base material30
Poly(methyl Methacrylate) Hard Contact Lenses
Water-soluble Polymer Soft Contact Lenses
Hydrogels Intraocular lenses
Contact Lenses And Intraocular Lenses
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• The function of a kidney is to remove low molecular
weight waste products from the bloodstream.
• Artificial kidneys have function by passage of the blood
between the walls of a dialysis cell which is immersed
in a circulating fluid.
• Cellophane- Semipermeable dialysis membranes
• The polymer is "heparinized" to prevent blood clotting-
polycarbonate or cellulose acetate fibers.
Artificial Kidney And Hemodialysis
Materials
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Surgical work on the heart frequently requires the
use of a heart lung machine to circulate and
oxygenate the blood.
Poly(dimethylsiloxane) membranes are highly
efficient gas transporters.
It is of interest that silicons rubber has approximately
six times the oxygen permeability of fluorosilicones.
Oxygen-Transport Membranes
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SURGICAL SUTURES
Poly(glycolic acid), or condensation copolymers of
glycolic acid with lactic acid.
A high tensile strength and is
compatible
The polymer degrades by hydrolysis to nontoxic
glycolic acid.34
Drug release by diffusionEarly encapsulation and entrapment systems released the drug from within the polymer via molecular diffusion◦ When the polymer absorbs water it swells in size◦ Swelling created voids throughout the interior polymer◦ Smaller molecule drugs can escape via the voids at a
known rate controlled by molecular diffusion (a function of temperature and drug size)
Addwater
Addtime
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Drug release by erosion• Modern delivery systems employ biodegradable
polymers– When the polymer is exposed to water hydrolysis occurs– Hydrolysis degrades the large polymers into smaller
biocompatible compounds
– Bulk erosion process – Surface erosion process
mer
Polymer
mer mer mer mer mer mer mer mer
Water attacks bond
mer mer mer mer mer mer mer mer mer
mer mer mer mer mer mer mer mer mer 36
Bulk erosion(e.g. poly lactide, polyglycolic acid)◦ When the polymer is exposed to water hydrolysis
occurs◦ Hydrolysis degrades the large polymers into
smaller biocompatible compounds◦ These small compound diffuse out of the matrix
through the voids caused by swelling◦ Loss of the small compounds accelerates the
formation of voids thus the exit of drug molecules
Addwater
Addtime
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Surface erosion(e.g., polyanhydrides)–When the polymer is exposed to water hydrolysis
occurs–Hydrolysis degrades the large polymers into smaller
biocompatible compounds–These small compound diffuse from the interface of
the polymer–Loss of the small compounds reveals drug trapped
within–Note these polymer do not swell.
Addwater
Addtime
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CONCLUSION
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Biomedical polymers are essentially a biomaterial, that is used and adapted for a medical application. Biomedical polymer can have a beginning functional, such as being used for a heart valve and more interactive purpose such as hydroxyapatite coated in implant and such implants are lunching upwards of twenty year. Many prostheses and implants made from polymers have been in use for the last three decades and there is a continuous search for more biocompatible and stronger polymer prosthetic materials.
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References
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ReferencesH.C.Paul, Textbook Of Polymer Chemistry(The Basic Concept), Marcel Dekker , Inc, pp-199-505.H.R.Allcock, F.W.Lampe, Textbook Of Contemporary Polymer Chemistry, 2ndEdition, Prentice Hall, INC, pp-575-589.J. H. Ward, R. Bashir, N.A. Peppas, Micropatterning Of Biomedical Polymer Surfaces By Novel UV Polymerization Techniques, 2001, John Wiley & Sons, Inc.,pp-351-360.M.A.Ward And T.K.Georgiou, Thermoresponsive Polymers For Biomedical Applications, 2011, Www.Mdpi.Com/Journal/Polymers, Polymers 3, pp-1215-1242.M.R.Aguilar, C. Elvira, A. Gallardo, B. Vázquez, And J.S. Román, Smart Polymers And Their Applications As Biomaterials, 2007, Topics In Tissue Engineering, Vol. 3 Eds, pp-1-27.N.K.Jain, Textbook Of Pharmaceutical Product Development, 1st
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