Biomedical polymers

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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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ReferencesN. R. Patel, P.P.Gohil, A Review on Biomaterials:Scope, Applications& Human Anatomy Significance, April 2012, Int J Emerging Technology and Advanced Engineering (ISSN 2250-2459, Volume 2, Issue 4), pp-91-101.N. Saha, A. Saarai, N. Roy, T. Kitano, P. Saha, Polymeric Biomaterial Based Hydrogels for Biomedical Applications, 2011 , Sci Res. J Biomaterials and Nanobiotechnology2, pp-85-90.Report On Radiation Synthesis And Modification Of Polymers For Biomedical Applications, 2002, International Atomic Energy Agency, pp-1-199.S. Brocchini, Combinatorial Chemistry And Biomedical Polymer Development, 2001, Elsevier Science, Advanced Drug Delivery Reviews 53, pp- 123 –130.T.J.Peter, Textbook Of Polymers For Controlled Drug Delivery, CRS Press, pp-99-148.www.google.com/search?q= polymer as a biomaterial.

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